Department of Transportation
Department of Transportation |
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| Preliminary Regulatory Impact Analysis | |
FMVSS 216, UPGRADE
ROOF CRUSH RESISTANCE
Office of Regulatory Analysis and Evaluation
National Center for Statistics and Analysis
August 2005
TABLE OF CONTENTS
APPENDIX A
This Preliminary Regulatory Impact Analysis examines the potential impacts of new performance requirements for passenger car and light truck roof strength. The intent of this proposal is to improve occupant protection in rollover crashes that involve roof crush.
Test Requirements
The agency is proposing to modify the test procedures in FMVSS No. 216 to require that vehicles be tested with the application of a force loading device up to 2.5 times the vehicle�s weight without the roof crushing to a level where it touches the head of a seated 50th percentile male dummy. This represents a change from the current requirement, which specifies a test load of only 1.5 times the vehicle�s weight without the device moving more than 127 millimeters (5 inches). The agency also examined an alternative proposal that would require a 3.0 load requirement.
Countermeasures
The agency believes that manufacturers will meet this standard by strengthening reinforcements in roof pillars, by increasing the gauge of steel used in roofs, or by using higher strength materials. The agency estimates that about 35 percent of all current passenger car and light truck models will require changes to meet the 2.5 vehicle load proposal, and that 75 percent would require changes to meet the 3.0 vehicle load alternative.
Benefits
The agency estimates that the proposed changes in FMVSS No. 216 requiring a load resistance of 2.5 times the vehicle weight would prevent from 13-44 fatalities and from 498 to793 nonfatal injuries. The range in these estimates reflects different methodological approaches that were employed to examine the injury profile of occupants in rollover crashes where the roof collapsed into the occupant compartment. The agency estimates that the alternative 3.0 times the vehicle weight load requirement would prevent from 49-135 fatalities and from 1,540-2,151 nonfatal injuries.
Costs
The design changes made to comply with higher test load requirements will add both cost and weight to the vehicle. This will increase the initial purchase price and reduce fuel efficiency, which will increase lifetime fuel usage costs. The agency estimates that compliance with the proposed 2.5 times the vehicle weight load requirement will increase vehicle costs by $10.67 per affected vehicle. Added weight is estimated to increase the lifetime cost of fuel usage by $5.33 to $6.69. The range in fuel costs reflects different discount rate assumptions of 7% and 3% respectively. The agency estimates that compliance with the proposed 3.0 times the vehicle weight load requirement will increase vehicle costs by $51.27 per affected vehicle. Added weight is estimated to increase the lifetime cost of fuel usage by $29.41 to $36.70 for the 3.0 times the vehicle weight load requirement alternative. The total annual consumer cost for the 2.5 times the vehicle weight load requirement proposal is from $88 to $95 million. The total annual consumer cost for the 3.0 times the vehicle weight load requirement proposal is from $1.2 billion to $1.3 billion.
Cost Effectiveness and Net Benefits
Cost effectiveness is a measure of the economic investment that is required to prevent a fatality. The cost effectiveness of this proposal was estimated under both 3% and 7% discount rate assumptions for each proposal. Nonfatal injuries were translated into fatality equivalents based on comprehensive valuations that included both economic impacts and valuations of lost quality of life. To reflect the present value of benefits that would be experienced over the vehicle�s useful life, the resulting equivalent fatalities were discounted over the vehicle�s life based on annual exposure to crash involvement as measured by annual miles traveled. The results indicate that the 2.5 times the vehicle weight load requirement proposal would cost from $2.1 million to $3.4 million per equivalent life saved. The 3.0 times the vehicle weight load requirement proposal would cost from $9.0 million to $14.4 million per equivalent life saved. The higher cost of the 3.0 times the vehicle weight load requirement alternative reflects the larger portion of the fleet that would have to be changed to meet the standard, as well as the greater cost and weight of design changes that would be required to achieve this level of roof strength.
The equivalent fatalities prevented are 39-55 fatalities for the 2.5 load factor and 122-171 fatalities for the 3.0 load factor. At the 3% discount rate this translates into 32-46 fatalities prevented for the 2.5 load factor and 100-140 fatalities prevented for the 3.0 load factor. At the 7% discount rate this translates into 26-37 fatalities prevented for the 2.5 load factor and 80-113 fatalities prevented for the 3.0 load factor.
Net benefits represent the difference between total costs and the total monetary value of benefits. The monetary value of benefits was estimated by assigning a value of $3.5 million to each equivalent fatality prevented. The 2.5 times the vehicle weight load requirement alternative would produce net benefits of from $3.0 million to $64.1 million. The 3.0 times the vehicle weight load factor alternative would result in net costs of $761 million to $909 million.
A. Current Requirements
FMVSS 216, "Roof crush resistance," became effective on September 1, 1973. This standard established strength requirements for the roof structure over the front occupants of passenger cars with a Gross Vehicle Weight Rating (GVWR) of 6,000 pounds or less. The purpose of the standard is to reduce deaths and injuries due to crushing of the roof into the passenger compartment area in rollover crashes. Since its inception, the roof crush standard has been amended, extending its requirements to passenger cars, trucks, buses, and multipurpose passenger vehicles (MPVs) with a GVWR of 2,722 kilograms (6,000 pounds) or less (55 FR 15510, April 17, 1991). The standard was also amended to modify the test device placement procedure to accommodate vehicles with raised and highly sloped (aerodynamic) roof structures (64 FR 22567, April 27, 1999).
The test procedure currently used to evaluate compliance with the standard involves securing a vehicle on a rigid horizontal surface, placing a flat steel rectangular plate on the vehicle�s roof, and using the plate to apply 1.5 times the unloaded weight of the vehicle (up to a maximum of 22,240 N, or 5,000 pounds, for passenger cars) onto the roof structure. During the test, the plate is angled and positioned to simulate vehicle-to-ground contact on the roof over the front seat area. [1]�To achieve this contact, the plate is tilted forward at a 5-degree angle, along its longitudinal axis, and tilted outward at a 25-degree angle, along it�s lateral axis, so that the plate�s outboard side is lower than its inboard side. The test plate�s edges are also positioned with respect to fixed locations on the vehicle�s roof, depending upon the roof slope, to ensure that the plate stresses the roof over the front seat area. Compliance with the standard is achieved if the vehicle�s roof prevents the test plate from moving downward more than 127 mm (5 inches).
B.������� Previous Agency Rulemaking
1.�������� Rollovers
In 1991, Congress mandated NHTSA to assess rulemaking on rollover occupant protection as a part of the Intermodal Surface Transportation Efficiency Act (ISTEA). ISTEA required the agency to initiate rulemaking to address the problems of rollover crashes. In response to that mandate, NHTSA published an advance notice of proposed rulemaking (ANPRM) (57 FR 242, January 3, 1991) that summarized the statistics and research in rollover crashes, sought answers to several questions about vehicle stability and rollover crashes, and outlined possible regulatory and other approaches to reduce rollover fatalities. NHTSA also published a report to Congress that detailed the agency�s effort in these areas (NHTSA 1999-5572-35).
The agency released a document entitled, "Planning Document for Rollover Prevention and Injury Mitigation," at a Society of Automotive Engineers (SAE) meeting on rollover on September 23, 1992. The planning document gave an overview of the rollover problem and a list of alternative actions that NHTSA was examining to address the problem. Activities described in the document included: crash avoidance research on vehicle measures for rollover resistance, research on antilock brake effectiveness, rulemaking on upper interior padding to prevent head injury, research on improved roof crush resistance to prevent head and spinal injury, research on improved side window glazing and door latches to prevent occupant ejection, and consumer information to alert people to the severity of rollover crashes and the benefits of seat belt use in this type of crash. NHTSA published a notice announcing the availability of the planning document and requesting comments (57 FR 44721, September 29, 1992).
In May 1996, NHTSA issued the "Status Report for Rollover Prevention and Injury Mitigation" (NHTSA 1996-1811-2). This document updated the progress of the programs discussed in the planning document. Under section 12 of the Transportation Recall, Enhancement, Accountability and Documentation (TREAD) Act of November 2000, NHTSA was mandated to develop a dynamic rollover test for the purposes of consumer information, to carry out a program of conducting such tests, and to conduct rulemaking to determine how best to disseminate test results to the public, as these tests are being developed. On July 3, 2001, the agency published a Request For Comment notice (66 FR 35179) discussing potential advantages and disadvantages of a variety of dynamic rollover tests that were selected to be evaluated in the agency�s research program. After a subsequent comment period, NHTSA published a NPRM on October 7, 2002, discussing the results of NHTSA's evaluation of numerous driving maneuver tests for the dynamic rollover consumer information program. The NPRM also proposed several alternative methods for using the dynamic rollover test results in the agency's consumer information for vehicle rollover resistance. NHTSA is now using the dynamic rollover testing to supplement the existing static ratings in the 2004 model year.
2.�������� Roof Crush
On April 17, 1991, NHTSA published a final rule amending FMVSS 216 to extend its requirements to MPVs, trucks, and buses with a GVWR of 2,722 kilograms (6,000 pounds) or less (56 FR 15510). NHTSA justified the extension to light trucks by the increased use of light trucks [2] as passenger vehicles and the need to ensure that those vehicles offer safety protection comparable to that offered to passenger cars. The final rule adopted the same test requirement and procedure as those for passenger cars, except for the absence of the 22,240 Newton limit on the applied force. This amendment became effective on September 1, 1994.
On May 6, 1996, the agency received a petition for rulemaking from R. Ben Hogan, Smith and Alspaugh, P.C. (Hogan). Hogan commented that the current static requirements in FMVSS 216 bear no relationship to real world rollover crash conditions and therefore should be replaced with a more realistic test such as the inverted vehicle drop test defined in the SAE Standard J996. This request coincided with agency research testing that was being conducted using the inverted drop test procedure. The petitioner also requested that NHTSA require "roll cages" to be standard in all cars as requested by some commenters responding to the January 3, 1992, ANPRM on rollover occupant protection. NHTSA granted this petition on January 8, 1997, believing that the inverted drop test had merit for further agency consideration.
On April 27, 1999, NHTSA published a final rule regarding the test procedure in FMVSS 216 (64 FR 22567). Prior to the amendments made by the final rule, the existing procedure resulted in certain vehicles with rounded roofs (e.g., the Ford Taurus) being tested with the test plate positioned too far rearward on the vehicle roof. In this position, the plate did not test the roof over the front occupants. In addition, this position created the potential for contact between the front edge of the test plate and the roof, allowing the plate to penetrate the roof along the leading edge of the plate. Similarly, in following this procedure for vehicles with raised, irregularly-shaped roofs (such as some vans with roof conversions), the initial contact point on the roof may not be above the front occupants, but on the raised rear portion of the roof, behind those occupants. In both of these cases, the positioning of the plate relative to the initial contact point on the roof, instead of relative to a fixed location on the roof, resulted in too much variability in the plate positioning and reduced test repeatability.
The April 27, 1999 final rule addressed the problem of rounded roofs by specifying a new primary test procedure for all vehicles except those with certain modified roof configurations. Under the new procedure, the test plate is positioned so that the front edge of the plate is 254 mm (10 inches) in front of the most forward point of the roof. Positioned in this way, the front edge of the plate is always projected slightly forward of the roof instead of contacting it. The rule addressed the problem for vehicles with raised or modified roofs by specifying a secondary test procedure if the initial point of contact is rearward of the front seat area. Under the secondary test procedure, the plate is moved forward such that its rearward edge is positioned at the rear of the roof over the front seat area.
In June 1999, RVIA and Ford submitted a petition for reconsideration regarding the rear edge plate contact on certain aerodynamically shaped roof vehicles with the secondary test procedure. To provide temporary relief, vehicle manufacturers, until October 25, 2000, had the option of using the standard's original test plate placement procedure (1973) for light trucks that have a raised or altered roof, in place of the primary or secondary procedures defined above (65 FR 4579, January 31, 2000). The original procedure positioned the plate with respect to its initial point of contact with the roof. The initial point of contact was established by angling and lowering the plate as required, following the primary test procedure until the plate contacts the roof. After establishing the initial contact point on the vehicle, the test plate was moved upwards, and the forward edge was positioned 254 mm (10 inches) forward of the initial point of contact with the vehicle. This position was allowed to make testing possible for raised roof vehicles that experience contact with the plate's rearward edge when testing to the secondary test procedure.
On October 22, 2001, NHTSA published a Request for Comment notice (66 FR 53376) to assist in the upgrade of FMVSS 216. In the Request for Comment, the agency discussed issues regarding the current standard and posed eight questions grouped according to the following areas: (1) current test procedures; (2) alternative dynamic tests; and (3) limiting headroom reduction. The agency has received numerous comments from the public.
In response to comments received in the October 2001 FMVSS 216 Request for Comments, NHTSA initiated a review of National Accident Sampling System � Crashworthiness Data System (NASS-CDS) investigated crashes�� The study was intended to evaluate if there were significant changes observed in the patterns of roof damage in the current fleet and to compare real-world roof damage to both compliance and extended FMVSS 216 tests. [3] This study examined rollover cases with greater than 15.2 cm (6 inches) of vertical intrusion contained in the most recent five years of NASS-CDS (1997 to 2001). The agency evaluated the damage to the A and B pillars, roof rails and roof plane of the vehicles. All the examined vehicles had considerably greater damage than FMVSS 216 compliance tests. The NASS-CDS case review revealed that lateral roof deformation that was limited to one side of the vehicle�s roof, happened frequently.
After the NASS-CDS case review, a finite element study was initiated to examine the effect of using alternative roll and pitch angles for the current FMVSS 216 test procedure. A finite element model of a 1997 Dodge Caravan was used to simulate extended FMVSS 216 tests for approximately five inches of plate motion using a variety of roll and pitch angles. The simulations indicated that the Caravan roof would attain similar amounts of deformation at a lower force level using 10-degree pitch and 45-degree (10-45) roll angles compared to the current 5-degree pitch and 25-degree (5-25) roll angles. A 1997 Chevrolet S10 pickup model was also studied, but the results were less conclusive.
The results of the finite element study were encouraging enough to conduct a series of modified FMVSS 216 tests. Two tests were conducted on the Dodge Caravan and Chevrolet S10 vehicles using both the current 5-25 roll angles as well as using modified 10-45 roll angles. A third vehicle, a 2002 Ford Explorer, was also tested using the same test configurations. Each test was conducted until 254 mm (10 inches) of load plate displacement was achieved.
The roof damage between the two test configurations was generally similar. The tests using 10-45 roll angles had some additional lateral damage, but the damage was localized near the roof side rail and did not extend laterally to the midline of the vehicle. The force distribution applied to the front and back of the load plate changed considerably between the two test configurations. The test configuration using the 10-45 roll angles applied almost all of the force to the forward ram located near the front of the load plate. The 5-25 configuration applied only two-thirds of the force to the front ram. Based on the similarity of the post-test damage patterns and general force levels, there was not sufficient evidence to justify changing the load plate configuration. Thus, the agency proposed to keep using the 5-25 roll angles in future FMVSS 216 upgrade testing.
| Vehicle | Ram Travel @150% |
Cos 25o | Test% Weight |
Ram Travel @250% |
Cos 25o |
Test % Weight |
Ram Travel @300% |
Cos 25o | |||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2002 Toyota Camry | 25 mm | 1.0 in | 0.9 in | 250 | 50 mm | 2.0 in | 1.8 in | 300 | 60 mm | 2.3 in | 2.1 in |
| 2002 Honda CRV | 33 mm | 1.3 in | 1.2 in | 250 | 112 mm | 4.4 in | 4.0 in | 300 | 140 mm | 5.5 in | 5.0 in |
| 1997 Dodge Grand Caravan | 38 mm | 1.5 in | 1.4 in | 250 | 85 mm | .3.3 in | 2.9 in | 265 | |||
| 2001 Chevy Tahoe | 40 mm | 1.6 in | 1.4 in | 250 | 65 mm | 2.6 in | 2.3 in | 290 | |||
| 1998 Chevy S-10 PU | 42 mm | 1.6 in | 1.5 in | 250 | 65 mm | 2.6 in | 2.3 in | 276 | |||
| 2002 Ford Mustang | 39 mm | 1.5in | 1.4 in | 250 | 115 mm | 4.5 in | 4.1 in | 265 | |||
| 2002 Ford Crown Vic | 49 mm | 1.9 in | 1.7 in | 250 | 190 mm | 7.5 in | 6.8 in | 300 | 245 mm | 9.6 in | 8.6 in |
| 2002 Ford Explorer | 43 mm | 1.6 in | 1.5 in | 250 | 215 mm | 8.5 in | 7.7 in | 300 | 255 mm | 10.0 in | 9.0 in |
| 2002 Dodge Ram 1500 PU | 45 mm | 1.7 in | 1.6 in | 249 - Fail | 100 mm | 3.9 in | 3.5 in | ||||
| 1999 Ford E150 Van | 50 mm | 2.0 in | 1.8 in | 188 - Fail | |||||||
| Indicates Pass at 300% | Indicates Failure at 300 % | Indicates Failure at 250% | |||||||||
A set of ten recent model vehicles, were tested using an extended FMVSS 216 procedure to gather further roof strength data. These vehicles were tested to 25.4 cm (10 inches) of load plate displacement. These vehicles included the following: 2002 Dodge Ram 1500 Pickup, 2002 Toyota Camry, 2002 Ford Mustang, 2002 Honda CRV, 2002 Ford Explorer, 2002 Ford Crown Victoria, 2001 Chevy Tahoe, 1999 Ford E-150, 1998 Chevy S10 Pickup, 1997 Dodge Grand Caravan. The test results are shown in Table II-1.
Additional instrumentation was included in all of the extended tests to measure the motion of the roof directly above the head of the 50th percentile dummy. Three string potentiometers were connected from the roof to known locations near the floor of the vehicle. These displacement measurements enabled the tracking of the motion of a single point on the roof during the test. These measurements were intended to provide some measure of the relationship between external plate displacement and available occupant headroom throughout the test. All of the extended FMVSS 216 tests used the seating procedure from the FMVSS 208 test procedure.
All ten vehicles in Table II-1 attained the FMVSS 216 required applied force of 1.5 times the unloaded vehicle weight within 5.1 cm (2 inches) of plate displacement. Nine of the ten vehicles exceeded an applied force of 2.0 times the unloaded vehicle weight within 7.6 cm (3 inches) of plate displacement. The Ford E-150 van never exceeded an applied force of 2.0 times the unloaded vehicle weight during the test. Six of the ten vehicles tested (1998 Chevy S10 Pickup, 2002 Toyota Camry, 2002 Honda CRV, 1997 Dodge Grand Caravan, 2002 Ford Mustang, and 2001 Chevy Tahoe) exceeded an applied force of 2.5 times the unloaded vehicle weight within the 127 mm (5 inches) of plate displacement allowed in the current standard.
The roof displacement measurements were combined with the initial occupant seating position to determine the initial occupant headroom. For the 10 vehicles tested in the research program, the initial headroom from the occupants head to the hard roof, ranged from 98 mm (3.9 inches) for the Ford Mustang to 254 mm (10 inches) for the Ford E-150. The depth of the roof liner varied considerably among the vehicles tested. The Ford Mustang had the smallest distance from the roof liner to the hard roof of 8 mm (0.3 inches), and the Ford E-150 van had the largest distance of 61 mm (2.4 inches).
String potentiometer measurements were used to track the 3-dimensional motion of the roof location directly above the occupant�s head. The post-test location of the roof attachment point was unlikely to be directly above the occupants head, however the downward displacement of this roof point is expected to provide an indication of the occupant headroom throughout the roof crush test. At an applied force of 1.5 times the vehicle weight, the occupant head-to-hard roof clearance ranged from 95 mm (3.7 inches) to 252 mm (9.9 inches). All of the test vehicles had greater than 100 mm of head-to-hard roof clearance except for the Ford Mustang. At 2.0 times the vehicle weight, the head-to-hard roof clearance ranged from 68 mm (2.7 inches) to 181 mm (7.1 inches) for the 9 vehicles that reached this force level. At 2.5 times the vehicle weight, the head-to-hard roof clearance ranged from 14 mm (0.5 inches) to 176 mm (6.9 inches) for the eight vehicles that reached this force level during the extended testing. If the liner depths did not change as the roof crushed, then at an applied force of 2.5 times the vehicle weight, six vehicles still had over 25 mm (1 inch) of head to roof liner clearance and 5 vehicles had over 75 mm (3 inches) of head-to-roof liner clearance. Even at 3.0 times the vehicle weight, two of the vehicles (Toyota Camry and Honda CRV) still had over 75 mm (3 inches) of head-to-roof linear clearance. While the string potentiometers were not an exact measurement of occupant headroom, they did provide useful insights into the performance tradeoffs that can exist between roof strength and occupant headroom.
After completing the initial research program, NHTSA conducted ten additional extended FMVSS 216 tests with a 50th percentile Hybrid III dummy to better assess occupant headroom as a function of applied force, by determining when the roof contacted the dummy�s head. The following vehicles were tested to 25.4 cm (10 inches) of load plate displacement:� 2003 Ford Focus, 2003 Chevy Cavalier, 2003 Subaru Forester, 2002 Toyota Tacoma, 2001 Ford Taurus, 2003 Chevy Impala, 2002 Nissan Xterra, 2003 Ford F-150, 2003 Ford Expedition, and 2003 Chevy Express 15-passenger van. The test results are shown in Table II-2.
These ten additional tests used the FMVSS 208 seating procedure to place the 50th percentile Hybrid III dummy in the occupant seat. The dummy was seated throughout the duration of the 25.4 cm (10 inch) displacement of the load plate. Video cameras tracked the interior roof as it approached the dummy�s head. For each vehicle, the agency tracked the force level and the load plate displacement, and recorded the point where the roof contacted the dummy�s head.
| Vehicle | Ram Travel @150% |
Cos 25o | Test % Weight |
Ram Travel @250% |
Cos 25o | Test % Weight |
Ram Travel @300% |
Cos 25o | |||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2003 Subaru Forester | 21 mm | 0.8 in | 0.7 in | 250 | 40 mm | 1.6 in | 1.5 in | 300 | 45 mm | 1.8in | 1.6 in |
| 2003 Chevy Impala | 32 mm | 1.3 in | 1.1 in | 250 | 53 mm | 2.1 in | 1.9 in | 300 | 63 mm | 2.5 in | 2.2 in |
| 2002 Nissan Xterra | 33 mm | 1.3 in | 1.2 in | 250 | 45 mm | 1.8 in | 1.6 in | 300 | 57 mm | 2.2 in | 2.0 in |
| 2003 Ford Focus | 30 mm | 12 in | 1.1 in | 250 | 60 mm | 2.4 in | 2.2 in | 275 | |||
| 2003 Chevy Cavalier | 32 mm | 1.3 in | 1.1 in | 250 | 68 mm | 2.7 in | 2.4 in | 263 | |||
| 2002 Toyota Tacoma | 38 mm | 1.5in | 1.4 in | 250 | 66 mm | 2.6 in | 2.4 in | 266 | |||
| 2003 Ford F-150 | 37 mm | 1.5 in | 1.3 in | 250 | 77 mm | 3.0 in | 2.7 in | 285 | |||
| 2001 Ford Taurus | 48 mm | 1.9 in | 1.7 in | 250 – Fail Head Touch |
90 mm | 3.5 in | 3.2 in | ||||
| 2003 Ford Expedition | 56 mm | 2.4 in | 1.6 in | 235 - Fail | 115 mm | 4.5 in | 4.1 in | ||||
| 2003 Chevy Express Van | 68 mm | 2.7 in | 2.4 in | 205 - Fail | 110 mm | 4.3 in | 3.9 in | ||||
| Indicates Pass at 300% | Indicates Failure at 300 % | Indicates Failure at 250% | |||||||||
All ten vehicles attained the FMVSS 216 required applied force of 1.5 times the unloaded vehicle weight prior to roof contact with the dummy�s head as shown in Table II-2. Seven vehicles exceeded an applied force of 2.5 times the unloaded vehicle weight, prior to roof contact with the dummy�s head, and three of the vehicles exceeded 3.0 times the unloaded weight of the vehicle.
The Subaru Forester even exceeded an applied force of 4.0 times the unloaded vehicle weight without roof contact with the dummy�s head. Among the ten vehicles tested, the roof contacted the dummy�s head between 82 mm (3.2 inches) and 185 mm (7.3 inches) of plate displacement.
A. Alternatives
The agency is considering upgrading the present roof crush resistance requirement in FMVSS 216 of 1.5 times the vehicle�s weight to 2.5 times the vehicle weight. The agency also considered upgrading the standard to 2.0 and 3.0 times the vehicle�s weight. All three alternatives include the additional requirement that no roof component can touch the head of a 50th percentile Hybrid III dummy when seated in the driver or front passenger seat. All three alternatives are discussed below:
B. 2.0 Times Vehicle Weight Alternative
As observed in Tables II 1-2 there are very few vehicles that would not pass a roof crush resistance of 2.0 times the vehicle�s weight when tested using an extended FMVSS 216 procedure. In fact, the Ford E-150 Van was the only vehicle of the 20 vehicles tested in these two tables that could not pass the 2.0 times the vehicle�s weight roof crush resistance. By this observation, the agency believes only increasing the roof crush resistance to a factor of 2.0 times the vehicle�s weight would accomplish very little, and the corresponding benefits would be equally inconsequential. Thus, the agency is not pursuing a 2.0 times the vehicle�s weight requirement, but will consider the higher 2.5 and 3.0 alternatives.
C. 2.5 Times Vehicle Weight Alternative
In Tables II-1 and II-2 seven of the twenty vehicles (35%) tested would not pass a roof crush resistance of 2.5 times the vehicle�s weight when tested using an extended FMVSS 216 procedure. When adjusted for current sales levels, failed vehicles represent 32.4% of the new passenger vehicle fleet. The resulting benefits and costs that correspond to these test results relative to a roof crush resistance requirement of 2.5 times the vehicle�s weight are discussed in Chapters IV and V, respectively.
D. 3.0 Times Vehicle Weight Alternative
In Tables II-1 and II-3 fifteen of the twenty vehicles (75%) tested would not pass a roof crush resistance of 3.0 times the vehicle�s weight when tested using an extended FMVSS 216 procedure. When adjusted for current sales levels, failed vehicles represent 84.3% of the new passenger vehicle fleet. The resulting benefits and costs that correspond to these test results relative to a roof crush resistance requirement of 3.0 times the vehicle�s weight are discussed in Chapters IV and V respectively.
E. Rollover Near Side/Far Side Roof Crush
The agency received comments from Public Citizen and the Center for Injury Research regarding near and far side testing. [4] The comments stated that vehicle occupants on the far side of the rollover have a much greater risk of serious injury than the occupants on the near side. The commenters suggested that the agency require that both sides of the roof on the same vehicle withstand a crush force of 2.5 times the unloaded vehicle weight. That is after the force is applied to one side of the vehicle, the vehicle is then repositioned and the force load is applied on the opposite side of the roof over the front seat area. Public Citizen cited a recent paper by researchers at Delphi Automotive and Saab, which compared the injury risk depending on the seating position of an occupant relative to the direction of the rollover crash. [5] From this study, Public Citizen concluded that belted, non-ejected occupants on the far side suffer 12 times the risk of serious injuries compared to belted, non-ejected occupants on the near side of the rolling vehicle. On July 26, 2004, JP Research, Inc. submitted an evaluation of the Delphi Automotive and Saab research paper. JP Research discussed the paper with the principal authors and verified that the paper contained errors. When these errors were corrected, the ratio of risk for serious injuries comparing the far to near side roof changed from 12 times, to between 2.4 to 1.
NHTSA performed an independent analysis using NASS-CDS from 1997 to 2002. The agency believes that there is no significant increase in risk for far side belted, non-ejected occupants. NHTSA analyzed NASS-CDS (1997 to 2002) data to evaluate the Delphi research paper with respect to merits of testing both sides of the roof over the front seat area. The analysis included belted front outboard adults who were not totally ejected in a manner similar to the Delphi research paper, but it further restricted the analysis to vehicles that rolled only two to four quarter turns to the side. We estimate the risk of a serious injury, defined as a maximum AIS injury of 3 or greater, to be 29 seriously injured persons per 1000 "far side" occupants and 30 seriously injured persons per 1000 "near side" occupants for a ratio of about 1 to 1.
The agency is committed to further far side research and testing to assure adequate protection is provided to the occupants on both sides of the vehicle. The agency plans to further evaluate the safety need for near and far side testing of the roof over the front occupant area of the same vehicle, before proposing such a requirement.
A. Effectiveness of Increased Roof Strength
Although a significant level of roof crush frequently occurs in rollover crashes, previous efforts to link roof crush to occupant injury have yielded mixed results. Bahling [6] compared dummy neck loadings in production vehicles to rollcaged vehicles and found that neck loads resulted from "diving" impacts where the torso momentum compresses the neck against the vehicle interior. They also concluded that the reduction in roof deformation in the rollcaged vehicle had no effect in reducing neck loads in the area of ground impact. In an early study, Huelke [7] concluded that no statistical relationship exists between the Abbreviated Injury Scale (AIS) and roof crush for restrained occupants in rollovers. Likewise, MacKay [8] used field accident investigations to conclude that seat belts did not reduce head injuries in rollovers. By contrast, Huelke [9] concluded that fatality rates were lower for belted occupants, but primarily due to ejection mitigation. In another early study Partyka [10], found that data in the National Crash Severity Study (NCSS) were too sparse to draw conclusions. In a more recent study of NASS-CDS data, Partyka [11] was unable to ascertain the significance of roof intrusion on injuries in rollover crashes because of concerns that roof intrusion might be a surrogate for crash severity rather than a single cause of injury, and that data was not available for non-injury contacts. Rains and Kanianthra [12] analyzed NASS-CDS data and found that indications that head injury increases with reductions in head room, but also found trends indicating higher risk of head injury with headroom reduction.
These previous efforts compared injury rates to factors such as roof strength and pre-crash headroom. However, a recent NHTSA analysis, which examined the relationship between injury and post crash headroom (Austin et al) [13] found a statistically significant relationship between injury rates and roof crush based on roof contact with the occupant�s head. The injury pattern was noticeably different (less serious) in cases where roof intrusion did not exceed the pre-crash headroom of the occupant � in other words, when the deformed structure did not intrude below the occupant�s head. The initial Austin et al study examined all rollover non-ejected, belted cases of head injury regardless of other injuries that the occupant incurred, whether they were caused by intrusion or not. However, the changes required by this proposal are limited to specific test loads. Many crashes are essentially catastrophic in nature � they impart stress loads on the vehicle�s roof that would overwhelm even the increased strength required by an upgraded test procedure. In order to estimate benefits from revisions to the standard, an estimate must be made of the number of cases where changes made to comply with the standard will actually impact deaths and injuries by reducing the level of intrusion enough so that it no longer extends below the occupant�s head.
To accommodate this approach, the Austin analysis was re-run with a more specific set of restrictions � i.e., belted non-ejected [14] rollover fatalities or injuries with vertical intrusion over the injured occupant�s seat, where the injury was caused by roof contact and the injury is the single maximum level injury experienced by the occupant. [15] Unbelted occupants were not considered because in a rollover without restraints they will essentially become moving objects within the vehicle and tying their injuries to vehicle crush (as opposed to their own movement) is problematic. The restriction to vertical intrusion over the occupant�s seat was necessary to establish cause and effect. The restriction to sole maximum injury level was made because if an occupant has multiple injuries at the same maximum level, they would still be injured at that level even if the intrusion-caused injury were eliminated. However, NHTSA recognizes that this might still improve the injured occupant�s outcome, and thus this approach gives a conservative estimate of safety benefits.
The calculation of benefits will be based upon the predicted change in post-crash headroom. Post-crash headroom is defined as the pre-crash space over the occupant�s head minus the amount of vertical intrusion of a roof component. This calculation makes use of the headroom measures in Consumers Union�s Consumer Report vehicle specification file. The Consumers Union headroom measures involve a 5�9" person who adjusts the seat to a "comfortable" position. The driver�s headroom was used for both front outboard-seating positions. The Consumers Union measures begin with model year 1987. If the MSN Autos web site did not indicate a redesign of the vehicle�s body, then headroom was carried over from one model year to the next to complete years for which headroom was missing. [16] Post-crash headroom was then determined in two steps. The first step involved adjusting the Consumers Union headroom by the difference between the tester�s seated height and the NASS-CDS occupant�s seated height. In both cases, seated height was estimated by taking 48 percent of standing height, which is based upon the 50th percentile male dummy. The second step involved subtracting the magnitude of vertical intrusion. In a relatively small number of cases, the intrusion was reported as a range rather than by an exact number. In these instances the range was replaced by the median of the range. In another relatively small number of cases where the Consumers Union headroom was unknown, the average vehicle headroom for the vehicle�s body type was used. However, for a significant number of cases, post-crash headroom could not be determined because the occupant�s height was unknown. These cases were excluded from the calculation of effectiveness.
To determine effectiveness, the relationship between the maximum injury severity of a head, neck, or face injury due to an intruding roof component and post-crash headroom for all occupants in the target population was examined. A wide variety of functional forms were explored, including linear functions, logarithmic functions, step functions, and functions involving percent reduction in headroom, but the only statistically significant result could be obtained using a dichotomous cut-point between no remaining headroom (negative post-crash) and remaining headroom (positive post-crash).
The resulting analysis is summarized in Table IV-1. Note that the distribution of cases where headroom is remaining results in a less severe injury profile (shifted towards less serious injuries), compared with cases where the roof intruded below pre-crash headroom.
Based on the data in Table IV-1, the "No Headroom" cases were redistributed using the injury profile found in the "Headroom Remaining" cases. This produced a revised injury profile for those cases. By comparing the revised No Headroom profile to the initial No Headroom profile, a theoretical safety impact was calculated and used to estimate an effectiveness rate. This rate was calculated as follows:
E = (Na-Nr)/Na
Where:
E = effectiveness in injury reduction for each specific level.
Na = initial incidence of injuries when No Headroom
Nr = revised incidence of injuries based on Remaining Headroom distribution.
The results indicate that, for the restricted target population, 92 percent of fatalities would be eliminated. In addition, about 30 percent of all MAIS 3-5 injuries, 68 percent of MAIS 2 injuries, and 70 percent of MAIS 1 injuries would be eliminated. Uninjured counts would increase by about 11 percent. Although these effectiveness rates seem high, remember that they only apply to the very narrow target population they were designed to address. If effectiveness were computed based on a broader definition of the rollover injury problem, effectiveness rates would be much lower.
The effectiveness indicates the predicted percent of the injuries at each level that would be prevented by shifting occupants with no remaining headroom to remaining headroom. Table IV-1 also contains the cases with missing headroom for completeness, and the totals for each injury level correspond to the total target population figures noted in bold in Table IV-4. These numbers also highlight again that the benefits for any change to FMVSS 216 are likely to be small because of the small proportion of occupants with relevant injuries even when the vertical intrusion of a roof component is likely to be below the top of their head.
| No Headroom |
Headroom Remaining |
Effectiveness | Missing Headroom |
Total | |||
|---|---|---|---|---|---|---|---|
| No relevant injury | 47,319 | 85.61% | 54,372 | 95.42% | 7,602 | 109,294 | |
| MAIS 1 | 3,863 | 6.99% | 1,207 | 2.12% | 69.7% | 661 | 5,731 |
| MAIS 2 | 3,212 | 5.81% | 1,059 | 1.86% | 68.0% | 261 | 4,532 |
| MAIS 3-5 | 422 | 0.76% | 303 | 0.53% | 30.4% | 81 | 807 |
| Fatal | 457 | 0.83% | 40 | 0.07% | 91.5% | 98 | 596 |
B. Target Population
The stated purpose of FMVSS 216 is to "reduce deaths and injuries due to the crushing of the roof into the occupant compartment".�This rationale, as well as the test procedure itself, suggest that the standard does not apply to all injured occupants of rollover crashes. Rather, it covers a more narrow set of injuries. Therefore, the target population, defined as occupants who are likely to benefit from a stronger roof due to an upgrade of FMVSS 216, is a subset of all occupants injured during a rollover. This section first explains the procedure for determining the target population. The section then describes the calculation of the population that may benefit from one of the two proposed upgrades.
The target population estimates are based on results from NASS-CDS from 1997 through 2002. The beginning year, 1997, is when NASS-CDS first recorded the exact magnitude of intrusion. At the time of this analysis, 2002 is the most recent year available. The vehicles considered for the benefit calculations are non-convertible light duty vehicles (NASS-CDS body type 2 through 49). Vehicle headroom is only available for vehicles of model year 1987 and later, and intrusion measures are only known for vehicles that were inspected by a NASS-CDS investigator. Therefore, older vehicles and vehicles that were not inspected were excluded from the analysis, but the sample weights were adjusted to reflect the estimated total number of NASS-CDS rollover vehicles. Finally, vehicles that rolled only one-quarter turn to the side or that experienced a collision with a fixed object (other than a bush, embankment, ditch, culvert, or the ground) to the top of the vehicle were excluded. Vehicles that rolled only one-quarter turn did not experience a roof-to-ground contact consistent with the test procedure. Likewise, vehicles where a tree or pole struck the roof experienced a more concentrated force than would occur solely with a ground contact.
The occupants counted for benefits calculations were not fully ejected, belted, aged 13 or older, and seated in one of the two front outboard seats of the vehicles described above. Based on data from 1997-2001 NASS-CDS we determined that an estimated 77 percent of the seriously and fatally injured with known serious injuries who were fully ejected in roof-involved rollovers received their most severe injury from outside of the vehicle and another estimated 3 percent received injuries of equal severity from both outside and inside the vehicle. Consequently, it appears that preventing ejection is the most important means for reducing injury to fully ejected rollover occupants. For occupants who were unbelted but not fully ejected, we could not establish a relationship between roof crush injuries and the magnitude of roof crush. The test itself measures roof strength over front outboard seats, for which NHTSA recommends that the occupants be aged 13 or older, and the potential benefits for other seating positions (if any) cannot be determined.
Occupants for whom injury severity was unknown and fatalities without injury information were excluded from the analysis, but the sample weights were adjusted to reflect the estimated total number of occupants at each injury level. Also, fatalities were adjusted to reflect the average number of non-convertible light vehicle rollover fatalities in Fatality Analysis Reporting System (FARS) from 1997 through 2002. Finally, the occupants in the target population had vertical intrusion of a roof component over their seating position, where a roof component includes the roof itself, roof side rails, front (windshield) and back (backlight) headers, A and B pillars, the sun visor, as well as any roof console, sunroof components, or roll-bar. This criterion ensures that affected occupants were exposed to roof crush. Finally, the occupant had to experience a relevant injury, which is defined as a head, face, or neck injury from a vertically intruding roof component into the occupant�s seating position. We also explored intrusion that was over the front middle seating position and lateral and longitudinal intrusion, but relaxing these assumptions did not change the results.
Table IV-2 demonstrates how each of the above restrictions reduces the injured population affected by roof crush relevant to FMVSS 216. The restrictions that matter the most appear to differ by the severity of injury. For serious injuries and fatalities, large drops occur when excluding fully ejected occupants. A second large drop occurs when excluding the unbelted who were not fully ejected. For minor and moderate injuries, large drops occur when excluding the unbelted. All four of the injury categories also experienced significant drops when excluding vehicles with no vertical intrusion of a roof component and when requiring that the occupant have a relevant injury. Finally, not all occupants with a relevant injury are applicable for benefits purposes. For survivors, only injured occupants where the relevant roof crush injury was the sole maximum severity (AIS) injury are included in the calculation of safety benefits lives saved. For fatalities, only those occupants for whom the relevant roof crush injury was either the sole maximum severity injury or one of the most severe injuries are counted for lives saved. This approach reflects the fact that eliminating one of two or more injuries of identical severity would not change the status of the occupant � they would still be injured at the same severity level. However, an analysis of head-injured fatality cases indicated that when 2 or more injuries of the same MAIS level occur to different body regions, the cause of death is overwhelmingly the head injury. Therefore, for fatalities, both sole MAIS injury cases and those cases with a head injury at MAIS that were not the sole MAIS were considered to be relevant injuries.
| Minor Injuries (AIS 1) |
Moderate Injuries (AIS 2) |
Serious Injuries (AIS 3-5) |
Fatalities | |
|---|---|---|---|---|
| Non-Convertible Light Vehicles in Rollovers | 212,340 | 39,379 | 23,793 | 9,942 |
| Roof-Involved Rollover | 173,428 | 33,930 | 21,005 | 8,585 |
| No Fixed Object Collision to Top | 165,730 | 30,616 | 19,454 | 7,426 |
| Not Totally Ejected | 161,893 | 26,404 | 12,833 | 3,559 |
| Using Safety Restraint | 118,098 | 14,738 | 9,592 | 2,026 |
| Front Outboard Seats | 103,932 | 14,119 | 9,003 | 1,780 |
| Not 12 Years Old or Younger | 101,654 | 14,064 | 8,974 | 1,764 |
| Roof Component Intrusion | 62,695 | 11,346 | 7,144 | 1,030 |
| Head, Neck, or Face Injury from Intruding Roof Component | 21,198 | 7,169 | 2,373 | 751 |
| Injury – Not MAIS | 0 | 2,262 | 1,354 | 155 |
| Injury at MAIS - Not Sole Injury | 15,467 | 375 | 213 | 371 |
| Sole MAIS Injury | 5,731 | 4,532 | 807 | 225 |
| Note: Occupants relevant for benefits calculations are in bold. | ||||
The target population relevant to FMVSS 216 (the bold numbers near the bottom of Table IV-2) is thus a relatively small subset of the occupants injured in rollovers. For fatalities, the estimated total for the target population is 6 percent of all non-convertible light vehicle rollover fatalities (596/9942). For minor and serious injuries, the estimated total is closer to 3 percent. There is an apparent jump in the moderate injury category where the target population is an estimated 12 percent of the total population, but this estimate is due in large part to two NASS-CDS cases with a combined annual weight of over 3,200. [17]
C. Approach and Methodology
Table IV-3 lists all relevant cases of fatal injury from the 1997-2001 NASS-CDS. These cases make up the weighted target population described in Table IV-2. In addition to case information, it lists occupant height, pre-crash headroom, intrusion levels, post-crash headroom, and the annual average weighted fatality counts that result from each case. Note that in 14 of the 32 fatality cases, intrusion levels exceed 10 inches, indicating a severe force level that caused significant crush to the roof. The impact that the proposed standards will have on safety will depend on the degree to which they reduce intrusion in these 32 cases.
There are two basic pass/fail criteria in the proposal. Vehicles will be tested using a standard plate mounted at an angle that simulates vehicle-to-ground contact over the front seat area. The plate will be pushed into the roof until a proposed force equal to 2.5 times the vehicle�s weight is attained. During this procedure, the roof cannot intrude below the head of a 50th percentile male dummy positioned in the drivers seat. Vehicles will fail the test if they are unable to withstand the force level, or if they withstand the force level but still allow the roof to intrude below the dummy�s head. In either case, the test would be terminated as a failure when contact is made with the dummy�s head.
| Year | CASE | OCC | CU Headroom (inches) | Intrusion (inches) | Occ Height (inches) | Post Crash Headroom (inches) | Post Crash Headroom 250% | Post Crash Headroom 300% | Est. Annual Average | Approach A: Target Pop 250% | Approach A: Target Pop 300% | Approach B: Target Pop 250% | Approach B: Target Pop 300% |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1997 | 48 | 1 | 3 | 12.6 | 70.9 | -10.5 | -7.8 | -7.4 | 4.48 | 0.0002 | 0.0006 | ||
| 1999 | 169 | 1 | 2.5 | 6.7 | 68.1 | -3.8 | -2.1 | -1.8 | 14.709 | 2.5318 | 3.4433 | ||
| 2001 | 20 | 1 | 3.5 | 13.4 | 70.9 | -10.8 | -8.1 | -7.7 | 9.081 | 0.0002 | 0.0005 | ||
| 2002 | 16 | 1 | 1.5 | 5.1 | 68.9 | -3.6 | -2.4 | -2.2 | 23.755 | 3.8165 | 4.824 | ||
| 2001 | 125 | 2 | 3 | 20.5 | 66.1 | -16.1 | -13.4 | -13 | 3.822 | 0 | 0 | ||
| 2002 | 73 | 1 | 4 | 11.8 | 68.9 | -7.8 | -5.1 | -4.7 | 20.637 | 0.0771 | 0.1704 | ||
| 1997 | 15 | 1 | 4 | 13.8 | 66.9 | -8.8 | -6.1 | -5.7 | 9.408 | 0.0002 | 0.0007 | ||
| 2002 | 59 | 1 | 4 | 5.9 | 74 | -4.3 | -2.8 | -2.6 | 13.41 | 5.3193 | 5.9173 | ||
| 2001 | 24 | 2 | 5 | 6.3 | 65 | 0.6 | 2.2 | 2.4 | 14.107 | 5.2648 | 5.671 | ||
| 1998 | 47 | 1 | 4 | 4.7 | 72 | -2.2 | -1.1 | -1 | 1.041 | 0.2348 | 0.2492 | ||
| 2001 | 131 | 2 | 5.5 | 3.9 | 74 | -0.8 | 0 | 0.1 | 9.08 | 9.0799 | 9.0799 | 0.1664 | 0.1757 |
| 2002 | 91 | 1 | 5 | 8.7 | 66.9 | -2.7 | -0.4 | -0.1 | 8.438 | 3.4905 | 4.1906 | ||
| 2002 | 189 | 1 | 3 | 2 | 79.1 | -1.5 | -1.2 | -1.2 | 13.41 | 0.2794 | 0.2794 | ||
| 2000 | 172 | 1 | 3.5 | 13.8 | 72 | -11.7 | -9 | -8.6 | 12.065 | 0.0001 | 0.0002 | ||
| 2000 | 2 | 1 | 2.5 | 5.5 | 70.1 | -3.5 | -2.2 | -2 | 21.821 | 5.7812 | 6.9538 | ||
| 1998 | 10 | 1 | 3 | 17.7 | 66.9 | -13.7 | -11 | -10.6 | 7.56 | 0 | 0 | ||
| 2000 | 68 | 1 | 4 | 18.1 | 66.1 | -12.7 | -10 | -9.6 | 29.935 | 0 | 0 | ||
| 2000 | 181 | 1 | 4.5 | 1.6 | 65 | 4.9 | 5.1 | 5.1 | 7.363 | 0.0053 | 0.0053 | ||
| 2001 | 143 | 2 | 4.5 | 18.9 | 70.1 | -14.9 | -12.2 | -11.8 | 3.822 | 0 | 0 | ||
| 2001 | 16 | 1 | 6 | 7.5 | 70.1 | -2 | 0 | 0.2 | 6.964 | 6.9644 | 6.9644 | 3.1832 | 3.3526 |
| 2000 | 167 | 1 | 4 | 11.4 | 64.2 | -5.1 | -2.4 | -2 | 12.065 | 0.0995 | 0.2053 | ||
| 2000 | 178 | 2 | 4 | 2.4 | 68.1 | 2.1 | 2.5 | 2.5 | 18.759 | 0.2237 | 0.2237 | ||
| 1998 | 130 | 1 | 2.5 | 11.4 | 16.075 | 0.0001 | 0.0004 | 0.0047 | 0.0126 | ||||
| 2002 | 182 | 2 | 4 | 9.4 | 63 | -2.6 | -0.1 | 0.2 | 11.232 | 11.232 | 1.3891 | 1.9311 | |
| 2001 | 28 | 1 | 4 | 2.8 | 74 | -1.2 | -0.7 | -0.6 | 6.795 | 0.1648 | 0.1863 | ||
| 2000 | 73 | 1 | 4.5 | 8.3 | 66.9 | -2.8 | -0.6 | -0.3 | 113.56 | 41.481 | 50.8107 | ||
| 1999 | 86 | 1 | 4.5 | 15.4 | 74 | -13.3 | -10.6 | -10.2 | 8.843 | 0 | 0 | ||
| 1997 | 180 | 1 | 5 | 12.2 | 68.1 | -6.8 | -4.1 | -3.7 | 14.241 | 0.1701 | 0.339 | ||
| 2000 | 76 | 1 | 6 | 6.7 | 77.2 | -4.6 | -2.9 | -2.6 | 27.609 | 8.0761 | 8.6514 | ||
| 1997 | 6 | 1 | 5.5 | 8.7 | 81.916 | 19.9148 | 25.7467 | 41.6019 | 48.0048 | ||||
| 2001 | 89 | 1 | 5 | 15 | 70.9 | -10.9 | -8.2 | -7.8 | 21.26 | 0.0003 | 0.0009 | ||
| Aggregate Impact | 36 | 53 | 123 | 146 | |||||||||
To estimate the impact that the proposed test requirements would have on roof intrusion, NHTSA examined the force deflection curves from a series of 20 quasi-static vehicle tests conducted to determine their performance under conditions that lead to roof crush. These tests were conducted over several minutes and produced about 900 separate data points to define the base deflection curves. The tests are further described in Chapter II, Agency Research and Test Results. An example of these curves (based on the Ford Taurus), which plot the displacement of the roof plate used in the test to the force applied (measured as a percent of vehicle weight), is shown (labeled baseline) in Figure A. The vehicles tested were designed to meet current testing standards, which specify a force of 1.5 times the vehicles� weight. In order to estimate vehicle behavior at the higher levels being proposed, NHTSA derived an adjustment factor by comparing the peak vehicle load experienced prior to estimated head contact [18] with the load that would be required under the proposal. This was done for the 6 vehicles that failed to achieve the proposed 2.5 force level and the 1 vehicle that failed to achieve the 2.0 force level. For example, the Taurus experienced a peak load of 2 times its weight, which passes a 2.0 alternative, but fails both the 2.5 proposal and the 3.0 alternative. Under the 2.5 proposal, the adjustment factor would be 1.25 (2.5/2.0). This factor was used to scale the original force deceleration curves to levels consistent with the proposed alternative requirements of 2.0 and 2.5. Similarly, the factor for the 3.0 alternative would be 1.5.
Manufacturers normally build a level of safety into their vehicle designs so that vehicles can routinely pass required test requirements. Table IV-4 illustrates these margins for our test vehicles. Within the 20 vehicles tested, this safety margin averaged about 83 percent, and the minimum margin was 25 percent. Under more difficult test requirements, manufacturers may not be able or willing to maintain the high average safety margins they experience under the current standard. However, NHTSA believes it is likely that manufacturers will maintain a safety margin equal to at least a minimum margin of 20 percent. We therefore examined scenarios that assume a 20 percent safety margin as well as the basic requirements. Separate curves were thus developed for 2.5, and 3.0 scenarios with this 20 percent safety margin. The 2.5 and 3.0 curves in Figure IV-A were thus derived as a simple proportional relationship between the current standard and the proposed standard. For example, the peak force for the Taurus occurred at about 2.0 x its curb weight (Table IV-4) at about 40,000 N of force. Assuming manufacturers will maintain a compliance margin of 20 percent for whatever changes they make, for the 2.5 requirements, this implies they will actually strengthen it to 3.0 (2.5x1.2). We estimated that the peak force to failure at 3.0 would be proportional to the ratio of the strength requirements - in this case 1.5 (3.0/2.0). Therefore we assume that the peak force at 3.0 would be about 60,000 N. (1.5x 40,000 N). The same proportion is applied to each point on the curve to produce the estimated scaled force deflection curve for a 2.5 requirement.�The resulting curves are shown together with the baseline curve for the Ford Taurus in Figure IV-A.
The benefits for the alternative load requirements will be evaluated using the crush measured in filed reported crash cases. For each crush measurement the change in static deflection between the baseline and alternative requirements, for equivalent energy absorption, will be used to estimate the change in vertical crush. Following development of these individual force deflection curves for the 7 vehicles that did not meet the 2.5 load requirement, each curve was integrated over its full test duration to estimate the total energy experienced at each point during the test. Using these data, energy was plotted as a function of deflection. The resulting curves are shown for the example vehicle in Figure IV-B. These curves were then analyzed to produce a set of reconfigured curves that plotted the change in deflection as a function of baseline deflection. These measurements were taken from Figure IV-B relative to the baseline curve, i.e., the deflection at each point on the baseline curve in Figure IV-B was compared to the deflection on each of the alternative load requirement curves to produce a difference that is reflected on the y-axis. The resulting curves are shown for the Ford Taurus in Figure IV-C. These curves describe the change that would be expected in intrusion levels for each level of base intrusion under the alternative roof strength levels. For example, for the Taurus, a rollover that would cause 200 mm of intrusion with its existing roof would cause about 40 mm less intrusion if the roof were strengthened to meet a 2.5 standard, and about 60 mm less intrusion in a roof that was strengthened to meet a 3.0 requirement.
| VEHICLE | ROOF STRENGTH %Vehicle Weight |
Compliance Margin |
|---|---|---|
| 1999 Ford E150 Van | 188 | 1.25 |
| 2003 Ford Taurus | 203 | 1.35 |
| 2003 Chevy Express Van | 205 | 1.37 |
| 2002 Ford Explorer | 235 | 1.57 |
| 2003 Ford Expedition | 238 | 1.59 |
| 2002 Ford Mustang | 244 | 1.63 |
| 2002 Ford Crown Victoria | 245 | 1.63 |
| 2002 Dodge Ram 1500 PU | 249 | 1.66 |
| 2003 Chevy Cavalier | 264 | 1.76 |
| 2003 Toyota Tacoma | 265 | 1.77 |
| 1997 Dodge Grand Caravan | 265 | 1.77 |
| 1998 Chevy S-10 PU | 275 | 1.83 |
| 2003 Ford Focus | 277 | 1.85 |
| 2003 Ford F-150 | 289 | 1.93 |
| 2001 Chevy Tahoe | 290 | 1.93 |
| 2002 Honda CRV | 305 | 2.03 |
| 2002 Toyota Camry | 315 | 2.10 |
| 2003 Chevy Impala | 316 | 2.11 |
| 2003 Nissan Xterra | 346 | 2.31 |
| 2003 Subaru Forester | 480 | 3.20 |
| Average | 275 | 1.83 |
The force displacement curves for seven tested vehicles were averaged to produce the deflection curve for the 2.5 alternative and the force displacement curves for fifteen vehicles were averaged to produce the curve for the 3.0 alternatives. These average curves are shown in Figure IV-D. A third order polynomial regression was then run for each curve in Figure D to produce a model of expected displacement impact from higher force levels. The resulting models for the two alternatives were as follows:
For 2.5 times vehicle weight�� y = -0.000005 x3 + 0.0021 x2 + 0.0482 x���� (r2 = 0.9984)
For 3 times vehicle weight����� y = -0.000005 x3 + 0.0021 x2 + 0.0802 x���� (r2 = 0.9990)
Where:
y = intrusion prevented (in mm)
x = baseline intrusion� (in mm)
These models were applied to baseline intrusion levels for each case that meets the definition of a relevant injury in our target population to estimate the hypothetical intrusion prevented by the increased force requirement. This was then added to the measured post-crash headroom to produce an estimate of the resulting hypothetical post crash headroom under each alternative. If the measured post-crash headroom was negative and the hypothetical post crash headroom was positive or zero, then that case would benefit from the new requirement. The weighted value of all such cases was then used as the target population and the effectiveness estimates discussed previously were applied to these totals to produce an estimate of benefits within the full vehicle fleet.
Due to the nature of the third order equation, there is an inflection point at which the curve begins to slope downward. This inflection point is realized after 254 mm, and therefore cannot be visualized on our curve fit. With very large baseline intrusions, represented by "x" in the equations, the intrusion prevented ("y") might become a negative value. Since the upgrade would never increase overall intrusion, we calculated the largest "y" value, and with the intrusion corresponding "x" value assumed that any baseline intrusion greater than "x" would have an intrusion prevented value of the maximum "y."� This assumption did not alter the benefits number because it only affected the most severe cases, which had little or no influence on the benefits calculations.
Table IV-3 contains results for each alternative using two different analytical approaches. The first approach (Approach A) analyzed specific cases in NHTSA�s NASS-CDS database to determine the impact that would occur in each case from added roof strength. However, due to a combination of a small sample of relevant cases and unknown data elements, this analysis suffered from gaps in data and spikes in case weights. An alternative analysis was thus performed based on a construct, which assumes a probability of occupant height in each vehicle equal to the national distribution of occupant heights (Approach B). This was done to mitigate the impact that specific driver characteristics had in determining the inclusion of the case. The theory behind this is that any size occupant might have been involved in a crash of each case�s specific intrusion magnitude. By reflecting the probability that the occupant was of a height that would benefit from specific reductions in roof crush, the spikes in case weights would be minimized. The agency recognizes that this method assumes a random relationship between the height of drivers and the headroom that exists in vehicles that they purchase. To the extent that drivers height and vehicle headroom are actually related, this second approach loses credibility. However, the agency did examine the relationship between vehicle headroom and occupant size and found no perceptible trends [19]. Table IV-5 displays the results of this analysis. Overall, taller drivers seem no more likely to be in vehicles with less headroom than do shorter drivers. It is likely that passengers adjust the seat backs and positions in their vehicles to prevent uncomfortable proximity to internal vehicle structures such as the roof. The agency seeks comment on these two approaches.
| Height in cm | <159 | 160-167 | 168-174 | 175-182 | 183-187 | 188+ | Total |
| Height in feet and inches | <5’3” | 5’3” to <5’6” |
5’6” to <5’9” |
5’9” to <6’0” |
6’0” to <6’2” |
6’2”+ | |
| <3” Headroom | 13% | 8% | 34% | 16% | 57% | 9% | 26% |
| (8) | (22) | (22) | (15) | (11) | (4) | (82) | |
| 3 to3.5” | 16% | 22% | 13% | 18% | 15% | 18% | 17% |
| (17) | (38) | (50) | (57) | (26) | (11) | (199) | |
| 4” + Headroom | 71% | 70% | 53% | 66% | 28% | 73% | 57% |
| (56) | (90) | (142) | (116) | (62) | (35) | (501) | |
| Total | 100% | 100% | 100% | 100% | 100% | 100% | 100% |
| (81) | (150) | (214) | (188) | (99) | (50) | (782) | |
| Missing Consumers Union Vehicle Headroom | 25 | ||||||
| Note:� These occupants from 1997 through 2001 NASS-CDS crash database were belted non-ejected front outboard occupants over 12 years old. They were in single-vehicle rollovers of more then one-quarter turn to the side or end-over-end. The vehicles were model years 1987 or later, not convertibles, not certified altered vehicles, not towing a trailing unit, and did not have a fixed object collision with the top of the vehicle. Also, cases with unknown values of occupant height and intrusion have been excluded. | |||||||
To adjust for occupant height probability in Approach B, the agency calculated the lower and upper height bounds of occupants that would benefit from the proposal. These bounds are a function of actual intrusion in the crash, the level of improvement that would be prevented in the crash, and the probability that occupants would be of a height that falls within these bounds. Actual intrusion was derived from NHTSA�s data files and the improvement in intrusion was estimated using the force displacement curves previously discussed.
The lower bound is a person for whom the amount of initial intrusion just reaches the top of their head. Therefore a marginal amount of prevented intrusion would give the occupant positive post-crash headroom. This is a lower bound because if the occupant was shorter, the initial intrusion would be above their head (positive post-crash headroom) and would not count for benefit purposes, i.e., they would be assumed to be uninjured by the roof intrusion in the crash. The equation that satisfies this condition would be:
Post-crash Headroom = 0
or
Pre-crash Headroom � Intrusion = 0
Where:
Pre-crash Headroom = (CU Headroom - (Occupant Height - 69)/0.48)
CU Headroom = CU headroom measurement for specific make/model vehicle in crash
69 = height in inches of CU tester
.48 = ratio of seated to standing height.
Intrusion = original intrusion recorded in the CDS data base converted from centimeters to inches
This equation is pre-crash headroom (CU headroom adjusted for the difference between the seated height of the actual occupant and the 69 inch tall CU tester) minus actual intrusion equals zero. Solving for occupant height, the lower bound becomes:
Occupant height = 69 + 0.48 * (CU Headroom - Intrusion)
The upper bound is a person for whom the intrusion that would occur under the upgrade just reaches the top of their head. In this case, the prevented intrusion is just enough to turn the case from negative to positive post-crash headroom. This is an upper bound because a taller person would still have negative post-crash headroom and would not count for benefits purposes. (Even though some intrusion was prevented, it would not be enough to create positive post-crash headroom). The equation that satisfies this condition would be:
Post-crash Headroom = -Prevented Intrusion
or
Pre-crash headroom - Intrusion + Prevented Intrusion = 0.
or
(CU Headroom - (Occupant Height - 69)/0.48) � Intrusion + Prevented Intrusion =0
In this case, post-crash headroom (pre-crash minus actual intrusion) would equal the amount of intrusion prevented under the proposal (because by definition initial headroom for an occupant of this height is zero). Note that in the original equation prevented intrusion is expressed as a negative number because it represents a reduction in intrusion levels. Solving this equation for occupant height, the upper bound becomes:
Occupant height = 69 + 0.48 * (CU Headroom � Intrusion + Prevented Intrusion)
Once the lower and upper heights were derived, we calculated the probability that a person randomly drawn from the US (adult) population would have a height between the lower and upper bound under the assumption of a normal distribution with mean height of 66.4 (average of men and women) and standard deviation of 3 from the CDC. This probability was then applied to the case weight for the specific CDS case to estimate a benefit impact.
Full fleet benefits would only be realized if changes were made to all vehicles. However, many vehicles already pass the proposed requirements. In Section III it is noted that 32.4 percent of tested vehicles failed the proposed test at 2.5 x vehicle weight. It is thus assumed that only 32.4 percent of the vehicle fleet will require changes and this failure rate is then applied to the full fleet benefits to estimate the safety impact of the 2.5 requirement on the failed portion of the fleet. For the 3.0 alternative, the failure rate was 84.3 percent. The results are summarized in Table IV-6.
| 2.5 Times Vehicle Weight | ||||||
|---|---|---|---|---|---|---|
| Relevant Population | Failure Rate | Effectiveness | Estimated Benefits | |||
| Approach A | Approach B | Approach A | Approach B | |||
| Fatalities | 36 | 123 | 0.324 | 0.9147 | 11 | 37 |
| MAIS 5 | 0 | 6 | 0.324 | 0.3037 | 0 | 1 |
| MAIS 4 | 5 | 54 | 0.324 | 0.3037 | 0 | 5 |
| MAIS 3 | 10 | 122 | 0.324 | 0.3037 | 1 | 12 |
| MAIS 2 | 2337 | 678 | 0.324 | 0.6802 | 515 | 150 |
| MAIS 1 | 952 | 1290 | 0.324 | 0.6969 | 215 | 291 |
| 3.0 Times Vehicle Weight | ||||||
| Relevant Population | Failure Rate | Effectiveness | Estimated Benefits | |||
| Approach A | Approach B | Approach A | Approach B | |||
| Fatalities | 53 | 146 | 0.843 | 0.9147 | 41 | 112 |
| MAIS 5 | 0 | 7 | 0.843 | 0.3037 | 0 | 2 |
| MAIS 4 | 5 | 60 | 0.843 | 0.3037 | 1 | 15 |
| MAIS 3 | 11 | 138 | 0.843 | 0.3037 | 3 | 35 |
| MAIS 2 | 2447 | 835 | 0.843 | 0.6802 | 1403 | 479 |
| MAIS 1 | 978 | 1510 | 0.843 | 0.6969 | 575 | 887 |
Adjustment for Electronic Stability Control
The data used to determine the target population were from the years 1997 through 2002. Vehicles on the road during that time frame generally were not equipped with electronic stability control (ESC). Evaluations of ESC in existing vehicles have found them to be highly effective in preventing single vehicle crashes. NHTSA estimates that roughly 18% of current MY 2005 vehicle fleets (17% of passenger cars and 19% of LTVs), now come equipped with ESC. An adjustment will be made to the 1997-2002 target population to reflect the impact of ESCs in the newer vehicle fleets that will be subject to the higher roof strength requirements of this proposal.���
The adjustment is a function of the increase in ESC penetration in the new vehicle fleet compared to the on-road fleet that is reflected in 1997-2002 NASS and FARS databases, the effectiveness of ESCs in reducing single vehicle crashes, and the portion of rollover crashes that occur in single vehicle crashes. The formula is as follows:
ESCf = (Pn-Pb)*e*s
Where
ESCf = ESC adjustment factorPn = Current (MY 2005) ESC penetration in new vehicle fleet
Pb = ESC penetration in the MY fleets that were on road during 1997-2002.
e = effectiveness of ESC against single vehicle crashes
s = portion of rollover crashes that occur in single vehicle crashes
The inputs and results of this estimate are shown in Table IV-7. Current and base penetration rates are NHTSA estimates based on an examination of ESC installation rates by model year. Effectiveness rates were derived from an evaluation of ESC effectiveness conducted by NHTSA. [20]�The portion of rollovers that are single vehicle crashes reflects consistent ratios found in FARS and CDS. Calculations were made separately for passenger cars and light trucks, and for fatal and nonfatal crashes to reflect variation in the available inputs. The vehicle types were combined based on the relative vehicle sales split of 8 million passenger cars and 9 million LTVs. The resulting separate adjustment factors for fatalities and nonfatal injuries will be applied to the appropriate target population injury categories.
| Fatalities | Nonfatal Injuries | |||
|---|---|---|---|---|
| PC | LTV | PC | LTV | |
| MY 2005 Vehicle % Installation | 0.173 | 0.191 | 0.173 | 0.191 |
| 97-02 On-road Fleet % Installation | 0 | 0 | 0 | 0 |
| Effectiveness | 0.298 | 0.626 | 0.35 | 0.67 |
| % Rollover Single Vehicle | 0.8 | 0.8 | 0.8 | 0.8 |
| Factor | -0.0412 | -0.0957 | -0.0484 | -0.1024 |
| Factor PC+LTV | -0.0700 | -0.0770 | ||
Adjustment for Increased Safety Belt Use
Safety belt use has increased significantly over the past 8 years. According to NHTSA�s National Occupant Protection User Survey (NOPUS), belt use increased steadily from 62% in 1997 to 80% in 2004. As discussed previously in this chapter, the target population for improved roof strength is strictly defined to include only belted occupants. Unbelted occupants who meet all other criteria are excluded. When compared to the rate of belt use reflected in the 1997-2002 databases, current high levels of safety belt use would increase the number of rollover cases that would potentially benefit from higher roof strength. An adjustment will be made to the 1997-2002-target population to reflect the impact of higher belt use rates that will be experienced by the newer vehicle fleets that will meet the higher roof strength requirements.
Table IV-8 shows the history of safety belt use rates over the past 8 years. Belt use has risen steadily since 1997 to a level that is 18 points higher in 2004 than in 1997. The average usage rate during the 1997-2002 period, which comprised the base years data for our target population, was 68.8%. Current (2004) usage is at 80%, which means there are 16.2 percent more vehicle occupants wearing their belts now than in the 1997-2002 period.
| Year | NOPUS (%) | 19972002 Avg |
|---|---|---|
| 1997 | 62 | |
| 1998 | 65 | |
| 1999 | 67 | |
| 2000 | 71 | |
| 2001 | 73 | |
| 2002 | 75 | 68.8333 |
| 2003 | 79 | |
| 2004 | 80 | |
| Increase % Belt Use = >>>> | 1.1622 | |
Observed usage is a reasonable indicator for use by persons involved in most nonfatal crashes. However, research has shown that usage in fatal crashes is lower than usage in the general driving population. This reflects the fact that occupants who don�t wear belts are more likely to die in a crash than belt wearers, and thus represent a higher relative portion of fatalities in crashes. The relationship between observed use and use in fatal crashes has been derived in a series of NHTSA analyses. [21]�The formula that establishes this relationship is:
Up = .43751Uo +.47249Uo2
Where
Up = use in potentially fatal crashes
Uo = Observed usage in the driving population
The above formula predicts the usage rate of all persons involved in potentially fatal crashes (both those saved by belts and those who die) as a function of observed use in the general population. It predicts a curvilinear relationship that reflects a greater increase in usage by those involved in potentially fatal crashes as observed usage approaches 100%. This occurs because the drivers who are most likely to be involved in fatal crashes are risk takers who are also the least likely to use safety belts. As overall belt use increases, they represent an ever-growing portion of the remaining unbelted occupant pool from which new belted riders are drawn. At current usage levels, unit increases in observed belt use result in greater increases in usage in potentially fatal crashes. To determine the usage rate by persons who are actually killed, an adjustment must be made to reflect the effectiveness of safety belts in preventing fatalities. The formula for this adjustment is:
Uf = [Up-(e*Uf)]/[1-(e*Uf)]
Where
Uf = Usage by fatalsUp = use in potentially fatal crashes
e = effectiveness of safety belts against fatalities
Table IV-9 lists the results of the calculations for the 1997-2002 base data and the current model year fleet:
| 1997-2002 Avg | 2004 | Percent Change | |
|---|---|---|---|
| Effectiveness | 50.0 | 50.0 | |
| Observed Use (Uo) | 68.83 | 80.00 | 1.1622 |
| UPFC from Uo | 52.50 | 65.24 | 1.2426 |
| Use in Fatals (Uf) | 35.60 | 48.41 | 1.3601 |
The above formulas and table show the predicted relationship between belt use changes at different levels. However, changes in belt use rates are not identical to changes in belted occupants. To determine the change in belted occupants, data from Table IV-2 were used to estimate the net impact of higher belt use on the target population. To accomplish this, it was assumed that belt use in potentially fatal crashes would increase by the rate predicted in Table IV-9, or 24.3%. This increase was used to calculate a new rate of use in potentially fatal crashes (PFC). The resulting rate was used to impute the total added belted cases in PFC. These added cases were assumed to be drawn proportionally from the unbelted populations of ejected and non-ejected occupants. Safety belts are estimated to be about 50% effective in reducing fatalities in passenger vehicles. For non-ejected occupants, it was assumed that belts would save 50% of the newly belted, leaving the remaining 50% as additions to the belted population. For ejected occupants, based on a study by Kahane [22], it was assumed that belts would prevent 91% of ejections for the newly belted. Based on a study by Winnicki, [23] preventing ejection eliminates 70 percent of fatalities. This implies that 63.7% of previously ejected fatalities that buckle up will be prevented. The remainder of the newly belted ejected fatalities would become additions to the belted population. The new belted population was then compared to the original belted population to determine the net increase in belted cases. The resulting factor, 1.28, will be applied to the fatality target population to reflect current higher belt use rates. The results of applying both the ESC and safety belt adjustment factors are summarized in Table IV-10.
| 2.5 Times Vehicle Weight | ||||||
|---|---|---|---|---|---|---|
| Target Population | 32.4% Fleet | Effectiveness | Estimated Benefits | |||
| Approach A | Approach B | Approach A | Approach B | |||
| Fatalities | 43 | 149 | 0.324 | 0.9147 | 13 | 44 |
| MAIS 5 | 0 | 6 | 0.324 | 0.3037 | 0 | 1 |
| MAIS 4 | 5 | 58 | 0.324 | 0.3037 | 0 | 6 |
| MAIS 3 | 11 | 133 | 0.324 | 0.3037 | 1 | 13 |
| MAIS 2 | 2536 | 736 | 0.324 | 0.6802 | 559 | 162 |
| MAIS 1 | 1033 | 1400 | 0.324 | 0.6969 | 233 | 316 |
| 3.0 Times Vehicle Weight | ||||||
| Target Population | 84.3% Fleet |
Effectiveness | Estimated Benefits | |||
| Approach A | Approach B | Approach A | Approach B | |||
| Fatalities | 64 | 176 | 0.843 | 0.9147 | 49 | 135 |
| MAIS 5 | 0 | 7 | 0.843 | 0.3037 | 0 | 2 |
| MAIS 4 | 6 | 65 | 0.843 | 0.3037 | 1 | 17 |
| MAIS 3 | 12 | 150 | 0.843 | 0.3037 | 3 | 38 |
| MAIS 2 | 2656 | 906 | 0.843 | 0.6802 | 1523 | 520 |
| MAIS 1 | 1062 | 1639 | 0.843 | 0.6969 | 624 | 963 |
A. Structure Upgrade Costs
During initial research in the roof crush upgrade program, the agency selected four vehicles that already had finite element (FE) models created for roof strength modeling improvements. These four vehicles were a 1998 Plymouth Neon sedan, a 1999 Ford E-150 Van, a 1997 Dodge Caravan, and a 1998 Chevrolet S-10 pick-up. The Neon and E-150 represented vehicles that could not withstand a roof crush force of twice their weight, when applying load via the FMVSS 216 test device. Through an iterative process, improvements were made until the Neon and E-150 could withstand a roof crush force of about 20 percent greater than 2.5 times their vehicle weight (about 3.0 times greater). The Caravan and S-10 represented vehicles that could withstand a roof crush of over 2.5 times their vehicle weight. Through an iterative process, improvements were made until the Caravan and S-10 could withstand a roof crush force of about 20 percent greater than 3.0 times their vehicle weight (about 3.6 times greater). The FE models were run by the National Crash Analysis Center � George Washington University, and a cost teardown analysis of the model improvements were developed by Ludtke & Associates and reported to the agency under contract DTNH22-00-C-02008.
The initial baseline crush test of the Neon showed the vehicle could withstand a roof crush force of about 188 percent of its weight. Cost estimates for improvement of the Neon to 2.5 times its weight plus a 20 percent margin of compliance were estimated based on the FE 1 Update Analyses that strengthened the following parts to the roof:� the outer A-pillars; the inner B- pillars; the outer B-pillars; and the roof inter rails. The end user (consumer) costs and material weights are shown in Table V-1.
| Part Description | Steel Baseline Characteristics | Steel Upgrade Characteristics | Material Weight (lbs) | Consumer Cost ($) |
|---|---|---|---|---|
| 2 Inner Roof Rails | 1.0mm 270Mpa | 1.2mm 270Mpa | 1.6 | 0.92 |
| 2 Outer A-Pillars | 1.0mm 270Mpa | 1.2mm 270Mpa | 0.9 | 0.51 |
| 2 Inner B-Pillars | 1.3mm 270Mpa | 1.6mm 270Mpa | 0.8 | 0.47 |
| 2 B-Pillars Outer Doubler | 0.7mm 270Mpa | 1.2mm 270Mpa | 1.9 | 1.11 |
| TOTAL | 5.2 | 3.02 |
The initial baseline crush test of the Ford E-150 showed the vehicle could withstand a roof crush force of about 188 percent of its weight. Cost estimates for improvement of the E-150 to 2.5 times the vehicle�s weight plus a 20 percent margin of compliance were estimated based on the FE Update Analyses that strengthened the following parts to the roof:� the front and rear roof headers; the roof material; the upper A-pillars; the door frames; the side roof rails; and the outer B-pillars. The end user costs and material weights are shown in Table V-2.
| Part Description | Steel Baseline Characteristics | Steel Upgrade Characteristics | Material Weight (lbs) | End User Cost ($) |
|---|---|---|---|---|
| 1 Rear Roof Header | 1.2mm 270Mpa | 1.5mm 400Mpa | 1.3 | 3.57 |
| 1 Front Roof Header | 1.2mm 270Mpa | 1.5mm 400Mpa | 1.8 | 4.00 |
| 1 Roof | 0.8mm 270Mpa | 1.0mm 400Mpa | 1.76 | 4.64 |
| 2 Upper A-Pillars | 1.5mm 270Mpa | 1.5mm 400Mpa | 0.0 | 5.60 |
| 2 Door Frames | 1.4mm 270Mpa | 1.5mm 270Mpa | 1.1 | 1.89 |
| 2 Side Roof Rails | 1.2mm 270Mpa | 1.5mm 400Mpa | 2.7 | 4.40 |
| 2 Outer B-Pillars | 1.2mm 270Mpa | 1.5mm 400Mpa | 1.4 | 5.57 |
| ��� Total | 10.06 | 29.66 |
The initial baseline crush test of the Dodge Caravan showed the vehicle could withstand a roof crush force of about 265 percent of its weight. Cost estimates for improvement of the Caravan to over 3.0 times plus its weight plus a 20 percent margin of compliance were estimated based on the Finite Element lt12 Update that strengthened the following parts to the roof:� the front roof header; the A-Pillar reinforcements; the inner B-pillars and the outer B-pillar reinforcements. The end user costs and material weights are shown in Table V-3.
| Part Description | Steel Baseline Characteristics | Steel Upgrade Characteristics | Material Weight (lbs) | End User Cost ($) |
|---|---|---|---|---|
| 1 Front Roof Header | 0.8mm 190Mpa | 1.7mm 300Mpa | 3.1 | 4.57 |
| 2 A-Pillar Reinforcements | 1.9mm 220Mpa | 1.9mm 420Mpa | 0.0 | 4.55 |
| 2 Inner B-Pillars | 1.7mm 220Mpa | 1.7mm 420Mpa | 1.9 | 9.76 |
| 2 Outer B-Pillar Reinforcements | 0.9mm 220Mpa | 1.9mm 420Mpa | 16.6 | 23.04 |
| Total | 19.7 | 41.91 |
The initial baseline crush test of the Chevrolet S-10 showed the vehicle could withstand a roof crush force of about 275 percent of its weight.�Cost estimates for improvement of the S-10 to over 3.0 times its weight plus a 20 percent margin of compliance were estimated based on the FE 3 Update Analyses that strengthened or added the following parts to the roof:� front and rear roof headers; middle roof rails; A-pillars; inner B-pillars; outer B-pillars; and the outer body side frames. The end user costs and material weights are shown in Table V-4.
| Part Description | Steel Baseline Characteristics | Steel Upgrade Characteristics | Material Weight (lbs) | End User Cost ($) |
|---|---|---|---|---|
| 1 Rear Header | 1.0mm 270Mpa | 1.5mm 350Mpa | 1.3 | 2.32 |
| 1 Front Header | 1.0mm 270Mpa | 1.5mm 350Mpa | 0.6 | 2.57 |
| 2 Middle Inner Roof Rails | 1.0mm 270Mpa | 1.5mm 350Mpa | 0.2 | 0.74 |
| 2 Inner A-Pillars | 1.0mm 270Mpa | 1.2mm 350Mpa | 2.2 | 6.89 |
| 2 Outer B-Pillars | 0.7mm 270Mpa | 1.0mm 270Mpa | 8.0 | 13.64 |
| 2 B-Pillar Inner Panels | 1.0mm 270Mpa | 1.5mm 350Mpa | 1.2 | 4.13 |
| 2 Body Side Tack Welds | 0.0 | -0.17 | ||
| 2 Body Side Outer Panels | 1.0mm 270Mpa | 1.2mm 350Mpa | 15.3 | 19.21 |
| 2 Brackets | 1.5mm 270Mpa | 1.5mm 350Mpa | 0.4 | 0.42 |
| 2 Nuts | 0.0 | 0.08 | ||
| Total | 29.2 | 49.83 |
Vehicle manufacturers normally include enough of a safety factor in their vehicle design to assure all their vehicles adequately will pass the test requirements. For the twenty vehicles tested, the margin of safety ranged from 25 to 220 percent, with an 83 percent average margin of compliance. The agency expects that most vehicle manufacturers would incorporate a minimum 20 percent compliance safety factor to assure passage of the roof crush requirement, when they redesign their roofs. The agency is proposing to upgrade the present roof crush resistance of 1.5 times the vehicle weight to 2.5 times the vehicle weight. The agency also considered upgrades of
2.0 and 3.0 times the vehicle and discussion of all three alternatives follows below. All three alternative levels also include the requirement, that the roof crush can not collapse to the point where the interior roof touches a front seated 50th percentile Hybrid III dummy.
The 2.0 Times Vehicle Weight Alternative
Nineteen of the twenty vehicles tested listed in Table V-5 tested for roof crush strength had roofs stronger than twice their weight. The only vehicle having roof strength less than twice its weight was the Ford E-150, which had a roof strength of 188 percent of its weight. As shown in Table VI-2 the cost to improve the Ford E-150�s roof crush resistance to 2.5 + 20 percent =3.0 times the vehicle weight is $29.66. For the twice the vehicle weight roof strength alternative, the agency expects a redesign of the E-150 would be improved to 2.0 + 20 percent = 2.4 times the vehicle weight, which is about half way between its� present 1.88 strength and the 3.0 strength. If the agency assumes the strength improvement has a liner relationship with the cost, the E-150 upgrade would cost $14.83 to pass the 2.0 upgrade alternative. With about 135,000 Ford E-150s in production annually, the cost to upgrade them would be about $2M. Based on current sales, the 20 vehicles in Table V-5 represent about 5.9M vehicles in a 17 M vehicle fleet. The cost to upgrade the vehicle fleet to a roof crush strength 2.0 times the vehicle weight would be (17/5.9) $2M = $5.8M. Over the total 17 M vehicle fleet, the average price increase would be $0.34 per vehicle.
The 2.5 Times Vehicle Weight Alternative
The 1997 Plymouth Neon and the 1999 Ford E-150 Van represent vehicles with roof strengths less than twice their weight that were strengthened to over 2.5 times + 20 percent of their weight. Thus, these two vehicles will be used as cost surrogates for vehicles upgraded to meet the requirement of 2.5 times the vehicle weight. As shown in Tables V-1 and V-2 the cost to improve the Neon and E-150 roof strength of 1.88 times their vehicle weight to 2.5 times their weight plus a 20 percent margin of compliance is $3.02 and $29.66 respectively. To determine the fleet cost of upgrading all vehicles to a roof strength of 2.5 times their vehicle weight, the present vehicle roof strengths can be compared with the percentage roof strength less than 2.5 times the vehicle weight plus a 20 percent margin of compliance, times the cost to strengthen the vehicle to 2.5 times the vehicle weight plus a 20 percent margin of compliance, times the portion of the vehicle population each vehicle represents. The estimated cost to strengthen the roofs of test vehicles and their representative fleet population and fleet cost are shown in Table V-5.
The cost correction factor (cf) in Table V-5 is calculated as follows:
cf = (300� - %vw)/112�Where
%vw is the percent of vehicle weight roof strength, and 112 is the range from 188 percent of the vehicle weight to 2.5+20 percent =300 percent of the vehicle weight.
Both the Neon and the E-150 had roof strength ratings of 1.88 x their weight. The average cost to strengthen the Neon and E-150 from 1.88 to 2.5 times their vehicle weight plus a 20 percent margin of compliance is ($3.02 + $29.66)/2 = $16.34. This cost is multiplied times the correction factor and the vehicle population to yield the annual vehicle fleet cost. The process was repeated for all seven of the twenty vehicles tested that failed the proposed strength requirement of 2.5 times the vehicle weight. These seven vehicles failing the proposed strength requirement of 2.5 represent a vehicle fleet population of about 1.9M vehicles out of about 5.9M vehicles at a cost of $20.3M, at an average cost of $10.67 per affected vehicle. Based on current sales, the 20 vehicles in Table V-5 represent about 5.9M vehicles in a 17 M vehicle fleet. The cost to upgrade the vehicle fleet to a roof crush strength 2.5 times the vehicle weight would be (17/5.9)($20.3M) = $58.6M. Over the total 17 M vehicle fleet, the average price increase is $3.45 per vehicle.
| Roof Strength % Vehicle Weight |
Cost Correction Factor |
Cost | Population | ||
|---|---|---|---|---|---|
| VEHICLE | (K) | $ (K) | |||
| 1999 Ford E150 Van | 188 | 1 | $16.34 | 135 | $2,206 |
| 2003 Ford Taurus | 203 | 0.87 | $14.15 | 432 | $6,113 |
| 2003 Chevy Express Van | 205 | 0.85 | $13.86 | 101 | $1,400 |
| 2002 Ford Explorer | 235 | 0.58 | $ 9.48 | 489 | $4,637 |
| 2003 Ford Expedition | 238 | 0.55 | $ 9.05 | 187 | $1,691 |
| 2002 Ford Crown Victoria | 245 | 0.49 | $8.02 | 171 | $1,372 |
| 2002 Dodge Ram 1500 PU | 249 | 0.46 | $7.44 | 391 | $2,909 |
| Sub-Total | 1906 | $20,329 | |||
| 2002 Ford Mustang | 261 | 154 | |||
| 2003 Chevy Cavalier | 264 | 321 | |||
| 2003 Toyota Tacoma | 265 | 158 | |||
| 1997 Dodge Grand Caravan | 265 | 430 | |||
| 1998 Chevy S-10 PU | 275 | 372 | |||
| 2003 Ford Focus | 277 | 253 | |||
| 2003 Ford F-150 | 289 | 840 | |||
| 2001 Chevy Tahoe | 290 | 529 | |||
| 2002 Honda CRV | 305 | 148 | |||
| 2002 Toyota Camry | 315 | 435 | |||
| 2003 Chevy Impala | 316 | 201 | |||
| 2003 Nissan Xterra | 346 | 85 | |||
| 2003 Subaru Forester | 480 | 54 | |||
| Sub-Total | 3980 | ||||
| TOTAL | 5886 | ||||
The 3.0 Times Vehicle Weight Alternative
Since the 1997 Dodge Caravan and the 1998 Chevrolet S-10 pick-up represent vehicles with roof strengths about 2.5 times their weight that are strengthened to 3.0 times their vehicle weight plus a 20 percent margin of compliance, these two vehicles can be used as cost surrogates for vehicles to meet the requirement of 3.0 times the vehicle weight. As shown in Tables V-3 and V-4 the cost to improve the Caravan and S-10 roof strength of 2.65 and 2.75 times their vehicle weight respectively to 3.0 times their weight plus a 20 percent margin of compliance is $41.91 and� $49.82 respectively. To determine the fleet cost of upgrading all vehicles to a roof strength of 3.0 times their vehicle weight, the present roof strengths can be compared with the percentage roof strength less than 3.0 times the vehicle weight, times the cost to strengthen the vehicle to 3.0 times the vehicle weight plus a 20 percent margin of compliance, times the portion of the vehicle population each vehicle represents. The cost to strengthen the roofs of test vehicles and their representative fleet population and fleet cost are shown in Table V-6.
The cost correction factor (cf) in Table V-6 is calculated as follows:� cf = (370 �- %vw)/100
Where %vw is the percent of vehicle weight roof strength, and 100 is the range from 270 percent of the vehicle weight to 370 percent of the vehicle weight.
| Roof Strength % Vehicle Weight |
Cost Correction Factor |
Cost | Population | ||
|---|---|---|---|---|---|
| (K) | $ (K) | ||||
| 1999 Ford E150 Van | 188 | 1.82 | $83.52 | 135 | $11,275 |
| 2003 Ford Taurus | 203 | 1.67 | $76.64 | 432 | $33,107 |
| 2003 Chevy Express Van | 205 | 1.65 | $75.72 | 101 | $7,648 |
| 2002 Ford Explorer | 235 | 1.35 | $61.95 | 489 | $30,294 |
| 2003 Ford Expedition | 238 | 1.32 | $60.57 | 187 | $11,327 |
| 2002 Ford Crown Victoria | 245 | 1.25 | $57.36 | 171 | $9,809 |
| 2002 Dodge Ram 1500 PU | 249 | 1.21 | $55.53 | 391 | $21,711 |
| 2002 Ford Mustang | 261 | 1.09 | $50.02 | 154 | $7,703 |
| 2003 Chevy Cavalier | 264 | 1.06 | $48.64 | 321 | $15,615 |
| 2003 Toyota Tacoma | 265 | 1.05 | $48.18 | 158 | $7,613 |
| 1997 Dodge Grand Caravan | 265 | 1.05 | $48.18 | 430 | $20,719 |
| 1998 Chevy S-10 PU | 275 | 0.95 | $43.60 | 372 | $16,218 |
| 2003 Ford Focus | 277 | 0.93 | $42.68 | 253 | $10,797 |
| 2003 Ford F-150 | 289 | 0.81 | $37.17 | 840 | $31,224 |
| 2001 Chevy Tahoe | 290 | 0.8 | $36.71 | 529 | $19,421 |
| 4963 | $254,481 | ||||
| 2002 Honda CRV | 305 | 148 | |||
| 2002 Toyota Camry | 315 | 435 | |||
| 2003 Chevy Impala | 316 | 201 | |||
| 2003 Nissan Xterra | 346 | 85 | |||
| 2003 Subaru Forester | 480 | 54 | |||
| Sub-Total | 923 | ||||
| TOTAL | 5886 | ||||
The average cost to strengthen the Caravan and S-10 from 265 percent and 275 percent respectively to 370 percent of their vehicle weight is ($41.91 + $49.82)/2 = $45.87. The finite element models yielded the actual value of 370%, while the agency was targeting 360 percent, which would be equal to 300 percent plus a 20 percent margin of compliance. This cost is multiplied times the correction factor and the vehicle population to yield the annual vehicle fleet cost.
Fifteen of the twenty vehicles tested failed the proposed 3.0 times the vehicle weight strength requirement. The correction factor was only calculated up to a 300 percent of vehicle weight roof strength, because it is assumed that vehicles that can pass the 3.0 requirement will not be redesigned. These fifteen vehicles that would fail the 3.0 requirement represent a vehicle fleet population of about 5.0M vehicles out of about 5.9M vehicles at a cost of $254 M, at an average cost of $51.27 per affected vehicle. Based on current sales, the 20 vehicles in Table V-6 represent about 5.9M vehicles in a 17 M vehicle fleet. The cost to upgrade the vehicle fleet to a roof crush strength 3.0 times the vehicle weight would be (17/5.9)($254) = $733M. Over the total 17 M vehicle fleet, the average price increase is $43.13 per vehicle.
C. Vehicle Weight Gain
Changes made to increase roof strength will involve stronger materials and or reinforcements that might increase the weight of the vehicle. This weight increase would have an adverse impact on the vehicle�s fuel economy and increase the fuel it consumes over its lifetime. The resultant potential fleet weight increases to strengthen the roofs of vehicles up to the proposed requirement, were calculated using the same procedure used to obtain the fleet structural material cost.
The 2.5 Times Vehicle Weight Alternative
The 1997 Plymouth Neon and the 1999 Ford E-150 Van represent vehicles with roof strengths less than twice their weight that were strengthened to over 2.5 times + 20 percent of their weight. These two vehicles will be used as weight gain surrogates for vehicles upgraded to meet the requirement of 2.5 times the vehicle weight. As shown in Tables V-1 and V-2 the weight added to improve the Neon and E-150 roof strength of 1.88 times their vehicle weight to 2.5 times their weight plus a 20 percent margin of compliance is 5.2 lbs and 10.06 lbs respectively. To determine the fleet weight gain of upgrading all vehicles to a roof strength of 2.5 times their vehicle weight, the present vehicle roof strengths can be compared with the percentage roof strength less than 2.5 times the vehicle weight plus a 20 percent margin of compliance, times the weight to strengthen the vehicle to 2.5 times the vehicle weight plus a 20 percent margin of compliance, times the portion of the vehicle population each vehicle represents. The estimated weight gain to strengthen the roofs of the test vehicles and their representative fleet population and fleet weight gain are separated in passenger car and light truck fuel economy groups as shown in Table V-7.
The weight correction factor (cf) in Table V-7 is calculated as follows:� cf = (300� - %vw)/112
Where %vw is the percent of vehicle weight roof strength, and 112 is the range from 188 percent of the vehicle weight to 2.5 + 20 percent� = 300 percent of the vehicle weight.
Based on the results of finite element modeling, the average weight gains to strengthen the Neon and E-150 from 1.88 to 2.50 times their vehicle weight plus a 20 percent margin of compliance are 5.2 lbs and 10.06 lbs respectively. These weights were multiplied times the strength correction factor and the vehicle population, to yield the annual vehicle fleet weight gain. The process was repeated for all seven of the twenty vehicles that failed the proposed 2.5 times the vehicle weight strength requirement. These vehicles were then separated into passenger car and light truck fuel economy groups. The seven vehicles failing the proposed 2.5 requirement, represent a vehicle fleet population of about 1.9M vehicles out of about 5.9M vehicles (total sales for the tested fleet) at an average weight gain of 4.03 lbs per affected passenger car and 6.07 lbs per affected light truck. The sales based failure rate among tested passenger cars was 30.7% (603,000/1,967,000). This implies a total of 9,895,516 lbs of added weight across the entire passenger car fleet (8 million passenger car sales x.3066 failure rate x 4.03 lbs). For LTVs, the failure rate is 34.7% (1,303,000/3,761,000) and the total added weight across the LTV fleet is 28,818,632 lbs. (9 million LTVs x .3465 failure rate x 6.07 lbs.). The average weight gain to upgrade the vehicle fleet to a roof crush strength 2.5 times the vehicle weight (spread over both passing and failing vehicles) would be (64,991,728 lbs)/(17M vehicles)� = 1.70 lbs per vehicle.
| PASS CARS Factor + 20% 200-300 Range |
Roof Strength % Vehicle Weight |
Weight Correction Factor |
Weight Gain (lbs) |
Population | |
|---|---|---|---|---|---|
| (K) | (K) lbs | ||||
| 2003 Ford Taurus | 203 | 0.87 | 4.50 | 432 | 1,946 |
| 2002 Ford Crown Victoria | 245 | 0.55 | 2.86 | 171 | 489 |
| Sub-Total | 603 | 2,435 | |||
| 2002 Ford Mustang | 261 | 154 | |||
| 2003 Chevy Cavalier | 264 | 321 | |||
| 2003 Ford Focus | 277 | 253 | |||
| 2002 Toyota Camry | 315 | 435 | |||
| 2003 Chevy Impala | 316 | 201 | |||
| Sub-Total | 1364 | ||||
| TOTAL | 1967 | ||||
| TRUCKS 2.5 Factor + 20% 200-300 Range VEHICLE |
Roof Strength % Vehicle Weight |
Weight Correction Factor |
Weight Gain (lbs) |
Population | |
| (K) | �(K) lbs | ||||
| 1999 Ford E150 Van | 188 | 1 | 10.06 | 135 | 1,358 |
| 2003 Chevy Express Van | 205 | 0.85 | 8.53 | 101 | 8612 |
| 2002 Ford Explorer | 235 | 0.58 | 5.84 | 489 | 2,855 |
| 2003 Ford Expedition | 238 | 0.55 | 5.57 | 187 | 1,041 |
| 2002 Dodge Ram 1500 PU | 249 | 0.46 | 4.58 | 391 | 1,791 |
| Sub-Total | 1303 | 7,907 | |||
| 1997 Dodge Grand Caravan | 265 | 430 | |||
| 1998 Chevy S-10 PU | 275 | 372 | |||
| 2003 Ford F-150 | 289 | 840 | |||
| 2001 Chevy Tahoe | 290 | 529 | |||
| 2002 Honda CRV | 305 | 148 | |||
| 2003 Nissan Xterra | 346 | 85 | |||
| 2003 Subaru Forester | 480 | 54 | |||
| Sub-Total | 2458 | ||||
| TOTAL | 3761 | ||||
Since the 1997 Dodge Caravan and the 1998 Chevrolet S-10 pick-up represent vehicles with roof strengths about 2.5 times their weight that are strengthened to 3.0 times their vehicle weight plus a 20 percent margin of compliance, these two vehicles can be used as weight gain surrogates for vehicles to meet the requirement of 3.0 times the vehicle weight. As shown in Tables V-3 and V-4 the weight added to improve the Caravan and S-10 roof strength of 2.65 and 2.75 times their vehicle weight respectively to 3.0 times their weight plus a 20 percent margin of compliance is 19.7 lbs and 29.2 lbs respectively. To determine the fleet weight gain of upgrading all vehicles to a roof strength of 3.0 times their vehicle weight, the present roof strengths can be compared with the present percentage roof strength less than 3.0 times the vehicle weight, times the weight gain to strengthen the vehicle to 3.0 times the vehicle weight plus a 20 percent margin of compliance, times the portion of the vehicle population each vehicle represents. The estimated weight gain to strengthen the roofs of test vehicles and their representative fleet population and fleet weight gain are shown in Table V-8.
The weight correction factor (cf) in Table V-8 is calculated as follows:�cf = (370� - %vw)/100
Where %vw is the percent of vehicle weight roof strength, and 100 is the range from 270 percent of the vehicle weight to 370 percent of the vehicle weight.
| PASS CARS 3.0 Factor + 20% Alternative |
Roof Strength % Vehicle Weight |
Weight Correction Factor |
Weight Gain (lbs) |
Population | |
|---|---|---|---|---|---|
| (K) | lbs (K) | ||||
| 2003 Ford Taurus | 203 | 1.67 | 40.83 | 432 | 17,639 |
| 2002 Ford Crown Victoria | 245 | 1.25 | 30.56 | 171 | 5,226 |
| 2002 Ford Mustang | 261 | 1.09 | 26.65 | 154 | 4,104 |
| 2003 Chevy Cavalier | 264 | 1.06 | 25.92 | 321 | 8,319 |
| 2003 Ford Focus | 277 | 0.93 | 22.74 | 253 | 5,753 |
| Sub-Total | 1331 | 41,042 | |||
| 2002 Toyota Camry | 315 | 435 | |||
| 2003 Chevy Impala | 316 | 201 | |||
| Sub-Total | 636 | ||||
| TOTAL | 1967 | ||||
| TRUCKS 3.0 Factor + 20% Alternate |
Roof Strength % Vehicle Weight |
Weight Correction Factor |
Weight Gain (lbs) |
Population | |
| (K) | lbs (K) | ||||
| 1999 Ford E150 Van | 188 | 1.82 | 44.50 | 135 | 6,007 |
| 2003 Chevy Express Van | 205 | 1.65 | 40.34 | 101 | 4,075 |
| 2002 Ford Explorer | 235 | 1.35 | 33.01 | 489 | 16,141 |
| 2003 Ford Expedition | 238 | 1.32 | 32.27 | 187 | 6,035 |
| 2002 Dodge Ram 1500 PU | 249 | 1.21 | 29.58 | 391 | 11,568 |
| 2003 Toyota Tacoma | 265 | 1.05 | 25.67 | 158 | 4,056 |
| 1997 Dodge Grand Caravan | 265 | 1.05 | 25.67 | 430 | 11,039 |
| 1998 Chevy S-10 PU | 275 | 0.95 | 23.23 | 372 | 8,641 |
| 2003 Ford F-150 | 289 | 0.81 | 19.80 | 840 | 16,636 |
| 2001 Chevy Tahoe | 290 | 0.8 | 19.56 | 529 | 10,347 |
| 3632 | 94,544 | ||||
| Honda CRV | 148 | ||||
| Nissan Xtera | 85 | ||||
| Subaru Forrester | 54 | ||||
| Sub-Total | 3919 | ||||
| Total | 5886 | ||||
Based on the results of finite element modeling, the average weight gains to strengthen the Dodge Caravan and Chevrolet S-10 from about 2.70 to 3.00 times their vehicle weight plus a 20 percent margin of compliance are 19.7 lbs and 29.2 lbs respectively. These weights were multiplied times the strength correction factor and the vehicle population, to yield the annual vehicle fleet weight gain. The process was repeated for all fifteen of the twenty vehicles that failed the proposed 3.0 times the vehicle weight strength requirement. These vehicles were then separated into passenger car and light truck fuel economy groups. The fifteen vehicles failing the proposed 3.0 requirement, represent a vehicle fleet population of about 5.0M vehicles out of about 5.9M vehicles (total sales for the tested fleet) at an average weight gain of 30.8 lbs per affected passenger car and 26.0 lbs per affected light truck. The sales based failure rate among tested passenger cars was 67.7% (1,331,000/1,967,000). This implies a total of 166,922,054 lbs of added weight across the entire passenger car fleet (8 million passenger car sales x .677 failure rate x 30.8 lbs). For LTVs, the failure rate is 92.7% (3,632,000/3,919,000) and the total added weight across the LTV fleet is 217,108,660 lbs. (9 million LTVs x .927 failure rate x 26.0 lbs.). The average weight gain to upgrade the vehicle fleet to a roof crush strength 3.0 times the vehicle weight (spread over both passing and failing vehicles) would be (384,030,714 lbs)/(17M vehicles)� = 22.6 lbs. per vehicle.
An average fleet weight gain by roof strength alternative summary is provided in Table V-9.
| 2.5 Alternative | 3.0 Alternative | |
|---|---|---|
| Passenger Cars | 4.03 lbs | 30.8 lbs |
| Light Trucks | 6.07 lbs | 26.0 lbs |
D. Fuel Economy Impacts
The impact of added weight on lifetime fuel economy is a function of mileage, survival probability, the price of gasoline, the change in vehicle fuel economy due to the added weight, and the discount rate chosen to express lifetime impacts in their present value. The projected price of gasoline was taken from the Department of Energy�s Annual Energy Outlook 2004 [24]. Fuel taxes of $0.38 per gallon are excluded since these are a transfer payment and not a cost to society. Gasoline prices are projected to increase steadily through 2025. A second group of adjustments to the price of gasoline were considered to account for externalities such as environmental costs and international oil market costs.
One product of the combustion of hydrocarbon fuels, such as gasoline and diesel, is CO2. The environmental and economic consequences of these releases are not included in the price of gasoline. While there are estimates of these consequences in the literature, the administration has not taken a position on their costs. Using estimates from the literature would result in very little savings on a per vehicle basis and they have not been included in this analysis.
A second environmental cost of gasoline use relates to the hydrocarbon and toxic chemical releases from the gasoline supply chain, including oil exploration, refining, and distribution. Marginal costs of these activities combined have been estimated at $0.02 per gallon. [25]
The Organization of Petroleum Exporting Countries (OPEC) operates as a cartel that restricts the supply of oil to escalate the price above the free-market level. The greater the consumption of oil, the higher will be the price. Since the higher price of oil applies to all oil imports from OPEC, not just the increased oil use, the financial cost to the United States exceeds the market payment for the increased amount. Leiby et al. [26] estimated this impact to be $3.00 per barrel. This equates to $0.07 per gallon ($3/42 gallons per barrel).
It is not clear that the relatively minor impact on vehicle weight would have any real effect on these externalities. The U.S. consumes about 20 million barrels of oil per day and worldwide consumption totals 75 millions barrels. We estimate the impact of the rule to be roughly 114 barrels per day. It is highly unlikely that this would cause any change at all in the price of oil. Moreover, changes in demand of this minor magnitude would likely be met first through reductions of refined petroleum rather than by increased oil exploration. Inclusion of estimates for these externalities therefore produces a conservative estimate of cost effectiveness. To reflect taxes and externalities, the price of gasoline has been reduced by $0.38 per gallon to account for taxes, and has been increased by $0.09 per gallon to account for environmental and economic considerations.
| Year | AE0 2004 Fuel Price Forecast (1) (2002$/gallon) | Total Federal and State Taxes (2) (2002$/gallon) | Fuel Price Excluding Taxes (2002$/gallon) | Value of Oil Import Externalities (2002$/gallon) | Social Value of Fuel Savings (2002$/gallon) |
|---|---|---|---|---|---|
| 2005 | $1.439 | $0.375 | $1.063 | $0.086 | $1.150 |
| 2006 | $1.450 | $0.375 | $1.074 | $0.086 | $1.161 |
| 2007 | $1.456 | $0.375 | $1.081 | $0.086 | $1.167 |
| 2008 | $1.461 | $0.375 | $1.086 | $0.086 | $1.173 |
| 2009 | $1.469 | $0.375 | $1.094 | $0.086 | $1.181 |
| 2010 | $1.469 | $0.375 | $1.094 | $0.086 | $1.181 |
| 2011 | $1.472 | $0.375 | $1.096 | $0.086 | $1.183 |
| 2012 | $1.467 | $0.375 | $1.092 | $0.086 | $1.178 |
| 2013 | $1.468 | $0.375 | $1.092 | $0.086 | $1.179 |
| 2014 | $1.467 | $0.375 | $1.092 | $0.086 | $1.178 |
| 2015 | $1.468 | $0.375 | $1.093 | $0.086 | $1.180 |
| 2016 | $1.472 | $0.375 | $1.097 | $0.086 | $1.183 |
| 2017 | $1.472 | $0.375 | $1.097 | $0.086 | $1.183 |
| 2018 | $1.471 | $0.375 | $1.096 | $0.086 | $1.182 |
| 2019 | $1.473 | $0.375 | $1.097 | $0.086 | $1.184 |
| 2020 | $1.473 | $0.375 | $1.097 | $0.086 | $1.184 |
| 2021 | $1.475 | $0.375 | $1.100 | $0.086 | $1.186 |
| 2022 | $1.480 | $0.375 | $1.104 | $0.086 | $1.191 |
| 2023 | $1.482 | $0.375 | $1.107 | $0.086 | $1.193 |
| 2024 | $1.489 | $0.375 | $1.114 | $0.086 | $1.200 |
| 2025 | $1.492 | $0.375 | $1.117 | $0.086 | $1.203 |
| (1) Average retail price for all grades of motor gasoline. Source: Energy Information Administration, Annual Energy Outlook 2004, Reference Case Forecast, Table 12, http://www.eia.doe.gov/oiaf/aeo/excel/aeotab_12.xls | |||||
| (2) Sum of Federal and sales-weighted average of state taxes on motor gasoline during 2002. Source: Federal Highway Administration, Highway Statistics 2002, Table MF-121T, http://www.fhwa.dot.gov/policy/ohim/hs02/xls/mf121t.xls | |||||
| Passenger Cars Vehicle Age� (years) |
Vehicle Miles Travelled |
Survival Probability |
Weighted Vehicle Miles Travelled |
Social Value Fuel Price per Gallon (2002 dollars) |
Fuel Consumption with Base Fuel Economy (gallons) |
Fuel Consumption with New Fuel Economy (gallons) |
Present� Value of Fuel Consumption (Base FE) |
Present� Value� of Fuel Consumption (New FE) |
|---|---|---|---|---|---|---|---|---|
| ------- | --------- | ----------- | --------- | -------------- | ------------ | ------------ | ---------- | ---------- |
| 1 | 13533 | 0.995 | 13,465 | $1.15 | 576 | 577 | $640.32 | $640.92 |
| 2 | 12989 | 0.988 | 12,833 | $1.16 | 549 | 550 | $575.74 | $576.28 |
| 3 | 12466 | 0.978 | 12,192 | $1.17 | 522 | 522 | $514.12 | $514.60 |
| 4 | 11964 | 0.962 | 11,509 | $1.17 | 492 | 493 | $455.61 | $456.03 |
| 5 | 11482 | 0.938 | 10,770 | $1.18 | 461 | 461 | $401.18 | $401.55 |
| 6 | 11020 | 0.908 | 10,006 | $1.18 | 428 | 428 | $348.33 | $348.66 |
| 7 | 10577 | 0.870 | 9,202 | $1.18 | 394 | 394 | $299.90 | $300.18 |
| 8 | 10151 | 0.825 | 8,375 | $1.18 | 358 | 359 | $254.17 | $254.41 |
| 9 | 9742 | 0.775 | 7,550 | $1.18 | 323 | 323 | $214.20 | $214.40 |
| 10 | 9350 | 0.721 | 6,741 | $1.18 | 288 | 289 | $178.70 | $178.87 |
| 11 | 8974 | 0.644 | 5,779 | $1.18 | 247 | 247 | $143.32 | $143.46 |
| 12 | 8613 | 0.541 | 4,660 | $1.18 | 199 | 200 | $108.35 | $108.45 |
| 13 | 8266 | 0.445 | 3,678 | $1.18 | 157 | 158 | $79.91 | $79.98 |
| 14 | 7933 | 0.358 | 2,840 | $1.18 | 121 | 122 | $57.62 | $57.67 |
| 15 | 7614 | 0.285 | 2,170 | $1.18 | 93 | 93 | $41.20 | $41.24 |
| 16 | 7308 | 0.223 | 1,630 | $1.18 | 70 | 70 | $28.92 | $28.95 |
| 17 | 7014 | 0.174 | 1,220 | $1.19 | 52 | 52 | $20.28 | $20.30 |
| 18 | 6731 | 0.134 | 902 | $1.19 | 39 | 39 | $14.06 | $14.08 |
| 19 | 6460 | 0.103 | 665 | $1.19 | 28 | 28 | $9.71 | $9.72 |
| 20 | 6200 | 0.079 | 490 | $1.20 | 21 | 21 | $6.72 | $6.73 |
| ------ | ------ | ------ | --------- | --------- | ||||
| 126,678 | 5,419 | 5,424 | $4392.37 | $4396.46 |
The baseline miles-per-gallon figure for cars is 27.5 mpg, and for light trucks is 22.2 mpg (the MY 2007 light truck standard). A sample calculation for passenger cars for the proposal is:
Where:
V = Vehicle miles traveled
S = Survival probability
w = Baseline vehicle weight
i =� Incremental weight from redesigned roof structure
fe = Baseline EPA fuel economy
.85 = Factor to derive on-road fuel economy from EPA fuel economy
p = Fuel price
d = Mid-year discount factor
This process is shown in Table V-11 where each year�s variables are combined to produce estimates of the impact on fuel consumption under both baseline and revised vehicle weights. Table V-11 reflects a 7 percent discount rate and a 4.03 lb. increase in the weight of an average 3460 lb. passenger car. Over the vehicles life, this increases fuel consumption by 5 gallons (5,424 - 5,419), with a present value of $4.09 ($4,396.46 - $4,392.37).
In Tables V-12 and V-13, the results of this process are summarized for each Alternative, and vehicle type under both a 3 percent and a 7 percent discount rate. The final column of each table shows the total cost under each scenario, reflecting the pass/fail rates under each alternative (32.4 percent failure rate for the 2.5 vehicle load alternative, and 84.3 percent failure rate under the 3.0 vehicle load alternative.) The results indicate that the present value of added fuel expendituresn would range from $29-37 million under the 2.5 vehicle load alternative, and from $422-$526 million for the 3.0 vehicle load alternative.
| PDV Cost/Vehicle | Failure | Affected | Total Fuel | ||
|---|---|---|---|---|---|
| (2002$) | Sales | Rate | Vehicles | Cost (2003$)* | |
| 7% Discount Rate | |||||
| LTV | $6.25 | 9000000 | .324 | 2916000 | $18,558,713 |
| PC | $4.09 | 8000000 | .324 | 2592000 | $10,795,397 |
| Total | $5.23 | 17000000 | .324 | 5508000 | $29,354,110 |
| 3% Discount Rate | |||||
| LTV | $7.98 | 9000000 | .324 | 2916000 | $23,695,765 |
| PC | $5.99 | 8000000 | .324 | 2592000 | $13,170,912 |
| Total | $6.57 | 17000000 | .324 | 5508000 | $36,866,677 |
| PDV Cost/Vehicle | Failure | Affected | Total Fuel | ||
|---|---|---|---|---|---|
| (2002$) | ����� Sales | ����� Rate | �� Vehicles | Cost (2003$)* | |
| 7% Discount Rate | |||||
| LTV | $26.78 | 9000000 | 0.843 | 7587000 | $206,900,231 |
| PC | $31.25 | 8000000 | 0.843 | 6744000 | $214,608,985 |
| Total | $28.88 | 17000000 | 0.843 | 14331000 | $421,509,216 |
| 3% Discount Rate | |||||
| LTV | $34.18 | 9000000 | 0.843 | 7587000 | $264,072,064 |
| PC | $38.13 | 8000000 | 0.843 | 6744000 | $261,857,300 |
| Total | $36.04 | 17000000 | 0.843 | 14331000 | $525,929,364 |
| Design Cost | Fuel Cost | Total Cost | |
|---|---|---|---|
| 7% Discount Rate | $58,575,000 | $29,354,110 | $87,929,110 |
| Per Unit Affected | $10.67 | $5.33 | $17.14 |
| 3% Discount Rate | $58,575,000 | $36,866,677 | $95,441,677 |
| Per Unit Affected | $10.67 | $6.69 | $18.50 |
Tables V-14 and V-15 provide a total cost summary of the 2.5 and 3.0 roof crush resistance alternatives at the 7 percent and 3 percent discount rates.
Certification and Compliance Test CostsThe agency believes the compliance test costs for the proposed alternatives will be about $5,000 per test, which is about twice the current cost per test. The increased cost is the result of a new tie down procedure, the increased test load, and the placement of a dummy in the front occupant seat to evaluate pass/fail headroom criteria. These changes increase the preparation time by approximately one day as compared to the present compliance test.
| Design Cost | Fuel Cost | Total Cost | |
|---|---|---|---|
| 7% Discount Rate | $733,250,000 | $421,509,216 | $1,154,759,216 |
| Per Unit Affected | $51.27 | $29.41 | $80.68 |
| 3% Discount Rate | $733,250,000 | $525,929,364 | $1,259,179,364 |
| Per Unit Affected | $51.27 | $36.70 | $87.97 |
The agency is proposing to make the requirements effective for all vehicles manufactured on and after the first September1 occurring three years (36 months) after the publication of the final rule. Based on recent agency testing, the agency estimates that 68 percent of the current fleet already complies with the proposed roof strength requirements. The three-year leadtime will allow manufacturers sufficient time to redesign weak roof structures and verify that their vehicles meet the new requirements.
A. Cost �Effectiveness Analysis
The cost of saving a life is one measure of the relative impact of a proposed regulation. When compared with similar cost measures for alternative approaches or existing regulations, it�provides a perspective on the relative merits of the regulation being considered. However, safety countermeasures usually mitigate nonfatal injury as well as death, and these impacts must also be factored into the calculation. This is done by measuring the cost per equivalent life saved. In order to calculate a cost per equivalent life saved, nonfatal injuries must be expressed in terms of fatalities. This is done by comparing the value of preventing nonfatal injuries to the value of preventing a fatality. Comprehensive values, which include both economic impacts and lost quality (or value) of life considerations will be used to determine the relative value of fatalities and nonfatal injuries. These values were taken from the most recent study on the cost of crashes published by NHTSA [27].�In Tables VII-1 and VII-2, the process of converting nonfatal injuries to its fatal equivalent is shown. The third column of Table VII-1 shows conversion factors that were derived from the comprehensive values used for each injury severity level.
In Chapter IV, benefits were derived under 2 different approaches for both the 2.5 and 3.0 force level alternatives. These results are shown in the first 2 columns of TablesVII-1 and VII-2. The fourth and fifth columns of these tables show the equivalent fatalities associated with each injury severity level. These values are derived by multiplying the conversion factors by the total injuries saved at each respective severity level.
| Estimated Benefits Approach |
Conversion Factor |
Equivalent Fatalities Approach |
|||
|---|---|---|---|---|---|
| A | B | A | B | ||
| Fatalities | 13 | 44 | 1 | 12.8 | 44.1 |
| MAIS 5 | 0 | 1 | 0.7124 | 0.0 | 0.5 |
| MAIS 4 | 0 | 65 | 0.2153 | 0.1 | 1.2 |
| MAIS 3 | 1 | 13 | 0.0916 | 0.1 | 1.2 |
| MAIS 2 | 559 | 162 | 0.0458 | 25.6 | 7.4 |
| MAIS 1 | 233 | 316 | 0.0031 | 0.7 | 1.0 |
| Total | 39.4 | 55.4 | |||
| Discounted @ 3% | 32.4 | 45.6 | |||
| Discounted @ 7% | 26.0 | 36.5 | |||
| Estimated Benefits Approach |
Conversion Factor |
Equivalent Fatalities Approach |
|||
|---|---|---|---|---|---|
| A | B | A | B | ||
| Fatalities | 49 | 135 | 1 | 49.3 | 135.3 |
| MAIS 5 | 0 | 2 | 0.7124 | 0.0 | 1.4 |
| MAIS 4 | 1 | 17 | 0.2153 | 0.3 | 3.6 |
| MAIS 3 | 3 | 38 | 0.0916 | 0.3 | 3.5 |
| MAIS 2 | 1523 | 520 | 0.0458 | 69.7 | 23.8 |
| MAIS 1 | 624 | 963 | 0.0031 | 1.9 | 3.0 |
| Total | 121.6 | 170.5 | |||
| Discounted @ 3% | 100.1 | 140.4 | |||
| Discounted @ 7% | 80.2 | 112.6 | |||
The results indicate that a 2.5 load factor would save the equivalent of 39-55 fatalities, while a 3.0 load factor would prevent from 122-171 equivalent fatalities.
At the bottom of each table the present discounted value of these equivalent fatalities is shown at a 3 percent and 7 percent rate. Discounting is required because the safety benefits will occur over the vehicle�s life, whereas design improvements will be paid for when the vehicle is purchased. The discounting process expresses both costs and benefits in terms of their present value. Passenger cars and light trucks experience different lifetime mileage schedules and survival patterns, which lead to different discount factors for each vehicle type. The adjustment factors used here assume a fleet of 9 million LTVs and 8 million passenger cars.
Table VII-3 lists the equivalent fatalities from Tables VII-1 and VII-2, as well as the total costs for each load alternative. The total costs consist of design costs, which are incurred through higher vehicle prices at the time of purchase, and lifetime fuel costs that occur due to added vehicle weight. Fuel costs, which occur over the vehicle�s life, are already expressed in present value terms. For each category, total costs are divided by equivalent fatalities to produce an estimate of the cost per equivalent fatality. For the 2.5 load factor, costs range from $2.1 million to $3.4 million per equivalent fatality. For the 3.0 load factor, costs range from $9.0 million to $14.4 million per equivalent fatality.
| Cost (millions 2003$) |
Equivalent Fatalities Approach |
Cost Per Equivalent Fatality ($2003 M) Approach |
|||
|---|---|---|---|---|---|
| A | B | A | B | ||
| 2.5 Load Factor | |||||
| Discounted @ 3% | $95.4 | 32.4 | 45.6 | $2.94 | $2.09 |
| Discounted @ 7% | $87.9 | 26.0 | 36.5 | $3.38 | $2.41 |
| 3.0 Load Factor | |||||
| Discounted @ 3% | $1,259.2 | 100.1 | 140.4 | $12.58 | $8.97 |
| Discounted @ 7% | $1,154.8 | 80.2 | 112.6 | $14.39 | $10.26 |
B. Benefit-Cost Analysis
Effective January 1, 2004, OMB Circular A-4 requires that analyses performed in support of proposed rules must include both cost effectiveness and benefit-cost analysis. Benefit-cost analysis differs from cost effectiveness analysis in that it requires that benefits be assigned a monetary value, and that this value be compared to the monetary value of costs to derive a net benefit. In valuing reductions in premature fatalities,� a value of $3.5 million per statistical life will be used. The most recent study relating to the cost of crashes published by NHTSA [28], as well as the most current DOT guidance on valuing fatalities [29], indicate a value consistent with $3.5 million. This value represents an updated version of a meta-analysis of studies that were conducted prior to 1993. More recent studies indicate that higher values may be justified. [30]
When accounting for the benefits of safety measures, cost savings not included in value of life measurements must also be accounted for. Value of life measurements inherently include a value for lost quality of life plus a valuation of lost material consumption that is represented by measuring consumers after-tax lost productivity. In addition to these factors, preventing a motor vehicle fatality will reduce costs for medical care, emergency services, insurance administrative costs, workplace costs, and legal costs. If the countermeasure is one that also prevents a crash from occurring, property damage and travel delay would be prevented as well. The sum of both value of life and economic cost impacts is referred to as the comprehensive cost savings from reducing fatalities.
The countermeasures that result from FMVSS 216 affect vehicle crashworthiness and would thus not involve property damage or travel delay. The 2002 NHTSA report cited above estimates that the comprehensive cost savings from preventing a fatality for crashworthiness countermeasures was $3,346,967 in 2000 economics. This estimate is adjusted for inflation to the 2002 cost level used in this report. Based on the CPI ALL Items index (179.9/172.2), this would become $3,496,6267. The basis for the benefit-cost analyses will thus be $3.5 million.
As a sensitivity analysis, we also examined a value of $5.5 million. This value represents the mean value between $1 million and $10 million, the range of values that are presumed to be plausible by OMB.
Total benefits are derived by multiplying the value of life by the equivalent lives saved. The net benefits are derived by subtracting total costs from the total benefits, as shown in Tables VII-4 and VII-5.
The results indicate that the proposed 2.5 force level requirements produce net benefits of between $3 million and $64 million when fatalities are valued at $3.5 million. When fatalities are valued at $5.5 million, the proposal produces net benefit ranging from $55 million to $155 million. The 3.0 alternative produces net losses ranging from $487 million to $909 million.
| Cost (millions$) |
(2003$) Equivalent Fatalities Approach |
�Benefits (millions$) Approach |
Net Benefit Approach |
||||
|---|---|---|---|---|---|---|---|
| A | B | A | B | A | B | ||
| 2.5 Load Factor | |||||||
| Discounted @ 3% | $95.4 | 32.4 | 45.6 | $113.4 | $159.5 | $17.99 | $64.08 |
| Discounted @ 7% | $87.9 | 26.0 | 36.5 | $90.9 | $127.9 | $3.01 | $39.95 |
| 3.0 Load Factor | |||||||
| Discounted @ 3% | $1,259.2 | 100.1 | 140.4 | $350.3 | $491.4 | -$908.90 | -$767.75 |
| Discounted @ 7% | $1,154.8 | 80.2 | 112.6 | $280.8 | $394.0 | -$873.96 | -$760.80 |
| Cost (millions$) |
Equivalent Fatalities Approach |
�Benefits (millions$) Approach |
Net Benefit Approach |
||||
|---|---|---|---|---|---|---|---|
| A | B | A | B | A | B | ||
| 2.5 Load Factor | |||||||
| Discounted @ 3% | $95.4 | 32.4 | 45.6 | $178.3 | $250.7 | $82.82 | $155.24 |
| Discounted @ 7% | $87.9 | 26.0 | 36.5 | $142.9 | $201.0 | $54.97 | 113.03 |
| 3.0 Load Factor | |||||||
| Discounted @ 3% | $1,259.2 | 100.1 | 140.4 | $550.4 | $772.2 | -$708.74 | -$486.93 |
| Discounted @ 7% | $1,154.8 | 80.2 | 112.6 | $441.3 | $619.1 | -$713.50 | -$535.69 |
� A. Regulatory Flexibility Act
The Regulatory Flexibility Act of 1980 (5 U.S.C. �601 et seq.) requires agencies to evaluate the potential effects of their proposed and final rules on small businesses, small organizations, and small governmental jurisdictions.
5 U.S.C. �603 requires agencies to prepare and make available for public comment an initial and final regulatory flexibility analysis (RFA) describing the impact of proposed and final rules on small entities if the agency decides that the proposal may have a significant economic impact on a substantial number of small entities. Each RFA must contain:
(1) A description of the reasons why action by the agency is being considered;
(2) A succinct statement of the objectives of, and legal basis for, the final rule;�
(3) A description of and, where feasible, an estimate of the number of small entities to which the final rule will apply;
(4) A description of the projected reporting, record keeping and other compliance requirements of a final rule including an estimate of the classes of small entities which will be subject to the requirement and the type of professional skills necessary for preparation of the report or record;
(5) An identification, to the extent practicable, of all relevant Federal rules which may duplicate, overlap or conflict with the final rule;
(6) Each final regulatory flexibility analysis shall also contain a description of any significant alternatives to the final rule which accomplish the stated objectives of applicable statutes and which minimize any significant economic impact of the final rule on small entities.
1. Description of the reasons why action by the agency is being considered
NHTSA has determined that the roof strength of some vehicles is below the level that can be achieved in an economically practicable manner and that improving the roof strength of these vehicles would prevent death and injury in rollover crashes.
2. Objectives of, and legal basis for, the final rule
Under 49 U.S.C. 322(a), the Secretary of Transportation (the "Secretary") has authority to prescribe regulations to carry out the duties and powers of the Secretary. One of the duties of the Secretary is to administer the National Traffic and Motor Vehicle Safety Act, as amended. The Secretary has delegated the responsibility for carrying out the National Traffic and Motor Vehicle Safety Act to NHTSA [31]. The agency is authorized to issue Federal motor vehicle safety regulations that meet the need for motor vehicle safety. NHTSA is issuing the final rule under 49 U.S.C. 322, 30111, 30115, 30117, 30166, and 30168; delegation of authority at 49 CFR 1.50.
3. Description and estimate of the number of small entities to which the final rule will apply
The final regulation would apply to motor vehicle manufacturers, final stage manufacturers, and alterers.
Business entities are defined as small businesses using the North American Industry Classification System (NAICS) code, for the purposes of receiving Small Business Administration assistance. One of the criteria for determining size, as stated in 13 CFR 121.201, is the number of employees in the firm. Affected business categories include:�(a) To qualify as a small business in Automotive Manufacturing (NAICS 336111), the firm must have fewer than 1000 employees., b) In the Light Truck and Utility Vehicle Manufacturing (NAICS 336112), the firm must have fewer than 1000 employees, c) In Motor Vehicle Body Manufacturing, the firm must have fewer than 1000 employees, d) In Motor Vehicle Seating and Interior Trim Manufacturing (NAICS 336360), the firm must have fewer than 500 employees, and e) In All Other Motor Vehicle Parts Manufacturing (NAICS 336399), the firm must have fewer than 750 employees.
Small motor vehicle manufacturers
There are 4 vehicle manufacturers that would qualify as a small business. Table VIII-1 provides information about the 4 small domestic manufacturers in MY 2004.
| Manufacturer | Employees | Estimated Sales | Sale Price Range |
Est. Revenues* |
|---|---|---|---|---|
| Avanti | 22 | 13 | $25,000 to $63,000 | $572,000 |
| Panoz | 50 | 150 | $90,000 to $125,000 | $16,125,000 |
| Saleen | 150 | 1,000 | $39,000 to $59,000 | $49,000,000 |
| Shelby | 44 | 60 | $42,000 to $135,000 | � $5,310,000 |
*� Assuming an average sales price from the sales price range
The average price increase per vehicle is estimated to range up to $3.45 (=$58.6 million / 17.0 million vehicles). Compared to the least expensive vehicle in Table VIII-1, the cost is less than two-hundredths of one percent ($3.88/$25,000 = .00014). Compared to a weighted average sales price ($58,000), the cost is about 6 thousandths of one percent ($3.45/$58,000 = .00006).
We believe that the market for the products of these small manufacturers is highly inelastic. Purchasers of these products are enticed by the desire to have an unusual vehicle. Thus, we do not believe that raising the price by this small amount will have any effect on vehicle sales. We
suspect these price increases will be passed on to the final customers. Based on this analysis, the agency believes that the final rule will not have a significant economic impact on these four small vehicle manufacturers.��
There are about 1000 final stage manufacturers and alterers, only a portion of which modify roof structures. These manufacturers will have to certify compliance with FMVSS 216 just as they currently do. NHTSA does not believe that there will be any appreciable change in the compliance burden for these small businesses.
Description of the projected reporting, record keeping and other compliance requirements for small entities
The agency is proposing to modify the test procedures in FMVSS 216 to require that vehicles be tested with the application of a force loading device up to 2.5 times the vehicle�s weight without the roof crushing to a level where it touches the head of a seated 50th percentile male dummy. �This represents a change from the current requirement, which specifies a test load of only 1.5 times the vehicle�s weight without the device moving more than 127 millimeters (5 inches). Manufacturers would have to certify their products comply with the rule.
4. Duplication with other Federal rules
There are no relevant Federal rules that may duplicate, overlap or conflict with the rule.
5. Description of any significant alternatives to the final rule
The agency is proposing to modify the test procedures in FMVSS 216 to require that vehicles be tested with the application of a force loading device up to 2.5 times the vehicle�s weight without the roof crushing to a level where it touches the head of a seated 50th percentile male dummy. NHTSA also examined an alternative to increase roof strength to 3.0 times the vehicles
In summary, the agency is proposing to modify the test procedures in FMVSS 216 to require that vehicles be tested with the application of a force loading device up to 2.5 times the vehicle�s weight without the roof crushing to a level where it touches the head of a seated 50th percentile male dummy. There are 18 vehicle manufacturers affected by this rule. Four of them are considered to be small businesses. Most of the intermediate and final stage manufacturers of vehicles built in two or more stages and alterers have 1,000 or fewer employees. However, there would be no significant economic impact on small business, small organizations, or small governmental units from this rule.
B. Unfunded Mandates Reform Act
The Unfunded Mandates Reform Act of 1995 (Public Law 104-4) requires agencies to prepare a written assessment of the costs, benefits, and other effects of proposed or final rules that include a Federal mandate likely to result in the expenditures by State, local or tribal governments, in the aggregate, or by the private sector, of more than $100 million annually (adjusted annually for inflation with base year of 1995). Adjusting this amount by the implicit gross domestic product price deflator for the year 2004 results in $118 million (108.237/92.106 = 1.18). The assessment may be included in conjunction with other assessments, as it is here.
This final rule is not estimated to result in expenditures by State, local or tribal governments of more than $118 million annually. It is not going to result in the expenditure by the automobile manufacturers and/or their suppliers of more than $118 million annually. The estimated annual consumer cost would be up to $88-95 million. These effects have been discussed previously in this Preliminary Regulatory Impact Analysis (see Chapter V, Costs).
Section 1(b) II of Executive Order 12866 Regulatory Planning and Review requires the agencies to take into account to the extent practicable "the costs of cumulative regulations". To adhere to this requirement, the agency has decided to examine both the costs and benefits by vehicle type of all substantial final rules with a cost or benefit impact effective from MY 1990 or later. In addition, proposed rules are also identified and preliminary cost and benefit estimates provided.
Costs include primary cost, secondary weight costs and the lifetime discounted fuel costs for both primary and secondary weight. Costs will be presented in two ways, the cost per affected vehicle and the average cost over all vehicles. The cost per affected vehicle includes the range of costs that any vehicle might incur. For example, if two different vehicles need different countermeasures to meet the standard, a range will show the cost for both vehicles. The average cost over all vehicles takes into account voluntary compliance before the rule was promulgated or planned voluntary compliance before the rule was effective and the percent of the fleet for which the rule is applicable. Costs are provided in 2000 dollars, using the implicit GNP deflator to inflate previous estimates to 2000 dollars.
Benefits are provided on an annual basis for the fleet once all vehicles in the fleet meet the rule. Benefit and cost per average vehicle estimates take into account voluntary compliance.
| Description | Effective Model Year |
Cost Per Affected Vehicle $ |
Cost Per Average Vehicle $ |
|---|---|---|---|
| FMVSS 114, Key Locking System to Prevent Child- Caused Rollaway |
1993 | $9.44 � 19.58 | $0.53 - 1.08 |
| FMVSS 214, Dynamic Side Impact Test | 1994 - 10% phase-in 1995 - 25% 1996 - 40% 1997 � 100% |
$69.06 � 672.59 | $62.52 |
| FMVSS 208, Locking Latch Plate for Child Restraints | 1996 | $0.89 � 17.93 | $2.40 |
| FMVSS 208, Belt Fit | 1998 | $3.41 � 17.09 | $1.26 - 1.82 |
| FMVSS 208, Air Bags Required | 1997 - 95% 1998 � 100 |
$503.50 � 608.39 | $503.50 � 608.39 |
| FMVSS 201, Upper Interior Head Protection | 1999 - 10% 2000 - 25% 2001 - 40% 2002 - 70% 2003 � 100% |
$37.76 | $37.76 |
| FMVSS 225, Child Restraint Anchorage Systems | 2001 - 20% 2002 - 50% 2003 - 100% |
$3.01 - $7.08 | $6.07 |
| FMVSS 208, Advanced Air Bags | Two phases 2003 to 2010 |
$24.15 to 134.40 | Depends on method chosen to comply |
| FMVSS 301, Fuel Tank Integrity Upgrade | 2007 - 40% 2008 - 70% 2009 - 100% |
$5.08 | $2.35 |
| FMVSS 202, Head Restraint Upgrade | 2009 | $8.10 to $17.15 | $10.70 |
| FMVSS 208, Rear Center Seat Lap/Shoulder Belts | 2006 - 50% 2007 - 80% 2008 - 100% |
$15.41 | $3.91 |
| Description | Fatalities Prevented | Injuries Reduced | Property Damage� Savings $ |
|---|---|---|---|
| FMVSS 114, Key Locking System to Prevent Child Caused Rollaway | None | 50-99 Injuries | Not Estimated |
| FMVSS 214, Dynamic Side Impact Test | 512 | 2,626 AIS 2-5 | None |
| FMVSS 208, Locking Latch Plate for Child Restraints | Not estimated | Not estimated | None |
| FMVSS 208, Air Bags Required Compared to 12.5% Usage in 1983 Compared to 46.1% Usage in 1991 |
4,570 - 9,110 2,842 - 4,505 |
AIS 2-5 85,930 - 155,090 63,000 - 105,000 |
None |
| FMVSS 201, Upper Interior Head Protection | 575 - 711 | 251 - 465 AIS 2-5 | None |
| FMVSS 225, Child Restraint Anchorage Systems� � Benefits include changes to Child Restraints in FMVSS 213 | 36 to 50* | 1,231 to 2,929* | None |
| FMVSS 208, Advanced Air Bags | 117 to 215** | 584 to 1,043 AIS 2-5** | Up to $85 per vehicle* |
| FMVSS 301, Fuel Tank Integrity Upgrade | 4 to 11 | none | none |
| FMVSS 202, Head Restraint Upgrade | None | 12,395 | None |
| FMVSS 208, Rear Center Seat Lap/Shoulder Belts | 16 | 279 | None |
* Total benefits for passenger cars and light trucks
** Total benefits for passenger cars and light trucks, does not count potential loss in benefits if air bags are significantly depowered.
| Description | Effective Model Year |
Cost Per Affected Vehicle $ |
Cost Per Average Vehicle $ |
|---|---|---|---|
| FMVSS 214, Side Impact Oblique Pole Test | TBD � first model year starting 4 years after final rule, then a 3 year phase in of 20%, 50%, all vehicles | $116 to $253 | $87 to $199 |
| Description | Fatalities Prevented |
Injuries Reduced |
Property Damage� Savings $ |
|---|---|---|---|
| FMVSS 214, Side Impact Oblique Pole Test | 343 to 516 | 440 to 519 AIS 3-5 |
None |
* Total benefits for passenger cars and light trucks
** Total benefits for passenger cars and light trucks, does not count potential loss in benefits if air bags are significantly depowered.
| Description | Effective Model Year |
Cost Per Affected Vehicle $ |
Cost Per Average Vehicle $ |
|---|---|---|---|
| FMVSS 202, Head Restraints | 1992 | $46.87 � 113.70 | $5.54 |
| FMVSS 204, Steering Wheel Rearward Displacement for 4,000 to 5,500 lbs. unloaded | 1992 | $6.05 � 29.95 | $1.07 � 2.03 |
| FMVSS 208, Rear Seat Lap/Shoulder Belts | 1992 | $69.25 | $0.41 |
| FMVSS 114, Key Locking System to Prevent Child- Caused Rollaway | 1993 | $9.44 � 19.58 | $0.01 - 0.03 |
| FMVSS 208, Locking Latch Plate for Child Restraints | 1996 | $0.89 - 17.92 | $2.40 |
| FMVSS 108, Center High-Mounted Stop Lamp | 1994 | $15.06 � 22.76 | $15.53 |
| FMVSS 214, Quasi-Static Test (side door beams) | 1994 - 90% 1995 � 100 |
$67.38 � 84.50 | $62.45 � 78.45 |
| FMVSS 216, Roof Crush for 6,000 lbs. GVWR or less | 1995 | $24.81 � 222.65 | $0.89 � 8.82 |
| FMVSS 208, Belt Fit | 1998 | $3.77 � 17.83 | $6.44 - 8.68 |
| FMVSS 208, Air Bags Required | 1998 - 90% 1999 � 100 |
$503.50 � 608.39 dual air bags | $503.50 � 608.39 dual air bags |
| FMVSS 201, Upper Interior Head Protection | 1999 - 10% 2000 - 25% 2002 - 70% 2003 - 100% |
$37.40 � 81.90 | $57.72 |
| FMVSS 225, Child Restraint Anchorage Systems | 2001 - 20% 2002 - 50% 2003 - 100% |
$3.01 - $7.08 | $6.07 |
| FMVSS 208, Advanced Air Bags | two phases 2003 to 2010 |
$24.15 to 134.40 | Depends on method chosen to comply |
| FMVSS 301, Fuel Tank Integrity Upgrade | 2007 - 40% 2008 - 70% 2009 - 100% |
$5.08 | $2.35 |
| FMVSS 202, Head Restraint Upgrade | 2009 | $8.10 to $17.15 | $10.70 |
| FMVSS 208, Rear Center Seat Lap/Shoulder Belts | 2006 - 50% 2007 - 80% 2008 - 100% |
$15.41 to $201.40 | $23.33 |
| Description | Fatalities Prevented | Injuries Reduced |
Property Damage Savings $ |
|---|---|---|---|
| FMVSS 202, Head Restraints | None | 470 - 835 AIS 1 20 - 35 AIS 2 |
None |
| FMVSS 204, Steering Wheel Rearward Displacement for 4,000 to 5,500 lbs. Unloaded | 12 � 23 | 146 - 275 AIS 2-5 | None |
| FMVSS 208, Rear Seat Lap/Shoulder Belts | None | 2 AIS 2-5 | None |
| FMVSS 114, Key Locking System to Prevent Child Caused Rollaway | None | 1 Injury | Not Estimated |
| FMVSS 208, Locking Latch Plate for Child Restraint | Not estimated | Not estimated | None |
| FMVSS 108, Center High Mounted Stop Lamp | None | 19,200 to 27,400 Any AIS Level | $119 to 164 Million |
| FMVSS 214, Quasi-Static Test (side door beams) | 58 � 82 | 1,569 to 1,889 hospitalizations | None |
| FMVSS 216, Roof Crush for 6,000 lbs. GVWR or less | 2 � 5 | 25-54 AIS 2-5 | None |
| FMVSS 208, Belt Fit | 9 | 102 AIS 2-5 | None |
| FMVSS 208, Air Bags Required Compared to 27.3% Usage in 1991 | 1,082 � 2,000 | 21,000 - 29,000 AIS 2-5 | None |
| FMVSS 201, Upper Interior Head Protection | 298 � 334 | 303 - 424 | None |
| FMVSS 225, Child Restraint Anchorage Systems� � Benefits include changes to Child Restraints in FMVSS 213 | 36 to 50* | 1,231 to 2,929* | None |
| FMVSS 208, Advanced Air Bags | 117 to 215** | 584 to 1,043 AIS 2-5** | Up to $85 per vehicle* |
| FMVSS 301, Fuel Tank Integrity Upgrade | 4 to 11 | none | none |
| FMVSS 202, Head Restraint Upgrade | none | 1,852 | None |
| FMVSS 208, Rear Center Seat Lap/Shoulder Belts | 17 | 253 | None |
* Total benefits for passenger cars and light trucks
** Total benefits for passenger cars and light trucks, does not count potential loss in benefits if air bags are significantly depowered.
| Description | Effective Model Year |
Cost Per Affected Vehicle $ |
Cost Per Average Vehicle $ |
|---|---|---|---|
| FMVSS 214, Side Impact Oblique Pole Test | TBD � first model year starting 4 years after final rule, then a 3 year phase in of 20%, 50%, all vehicles | $116 to $253 | $87 to $199 |
| Description | Fatalities Prevented |
Injuries Reduced | Property Damage� Savings $ |
|---|---|---|---|
| FMVSS 214, Side Impact Oblique Pole Test | 343 to 516 | 440 to 519 AIS 3-5 | None |
Vehicles that do not meet the proposed strength requirements of FMVSS 216 will require design modifications that could result in added weight to the roof and roof support structure [32]. To the extent that these changes impact the upper structure disproportionately, they have the potential to increase the height of the vehicle�s center of gravity (cg). This, in turn, could slightly increase the propensity of the vehicle to roll over under some impact or maneuvering circumstances. This appendix examines the potential impact of this effect on the Agency�s proposal to increase roof strength. First an examination is made of the change in rollover propensity that could result for the 4 vehicles for which the agency has finite element models to estimate changes (only 2 of which reflect the 2.5 x vehicle weight proposal). An analysis of potential safety impacts is then made based on a larger sample of vehicles under assumptions that link design changes to each vehicle�s relative roof strength when compared to the two vehicles for which finite element modeling is available.
Methodology
NHTSA research has firmly established the relationship between a vehicle�s physical characteristics and its rollover propensity. As an ongoing part of NHTSA�s New Car Assessment Program (NCAP), NHTSA developed a ratings system to measure the propensity of vehicles to roll over in a crash. This system is based upon the Static Stability Factor (SSF). The SSF is a measure of the vehicle�s physical tendency to roll over given its basic dimensions. It is essentially a measure of how top-heavy the vehicle is relative to its track width. Specifically, it is a function of the vehicle�s track width and center of gravity. The formula for SSF is:
SSF = T/(2*cg)
Where
cg = the height of the center of gravity of the vehicle, typically measured in a laboratory to determine the height of the center of the vehicle�s mass.
SSF is used in conjunction with a formula that was developed to predict the actual probability of a vehicle experiencing a rollover in a single vehicle crash given its SSF. This formula is derived from real world crash experience and its relationship to SSF. SSF is the single variable in this formula. Thus, a change in a vehicle�s SSF will produce a change in its estimated rollover propensity. The formula is:
R = 1/(1+e2.8891+1.16868*ln(SSF-0.9))
Where
A modified version of this formula has been developed for application to vehicles that tip up in NHTSA�s NCAP rollover test. However, none of the 4 vehicles that were analyzed using the finite element model vehicles fall into this category.
This formula thus provides a basis for estimating the safety impact of shifts in cg from design changes made to comply with FMVSS 216.
Estimated Shift in cg � 4 examples
There is very little data available to estimate the impact on cg that might result from changes to FMVSS 216. At this time, NHTSA has estimates of possible design changes based on finite element models (FEM) created for 4 different vehicles. During initial research in the roof crush upgrade program, the agency selected four vehicles that already had FEMs created for roof strength modeling improvements. These four vehicles were a 1998 Plymouth Neon sedan, a 1999 Ford E-150 Van, a 1997 Dodge Caravan, and a 1998 Chevrolet S-10 pick-up. The Neon and E-150 represented vehicles that could not withstand a roof crush force of twice their weight, when applying load via the FMVSS 216 test device. Through an iterative process, improvements were made within the FE models until the Neon and E-150 could withstand a roof crush force of about 20 percent greater than 2.5 times their vehicle weight (about 3.0 times greater). The Caravan and S-10 represented vehicles that could withstand a roof crush of over 2.5 times the r vehicle weight. Through this same iterative process, improvements were made until the Caravan and S-10 could withstand a roof crush force of about 20 percent greater than 3.0 times their vehicle weight (about 3.6 times greater). The agency thus has an analysis of possible design changes for 2 models under the proposed 2.5 load, and 2 models under the alternative 3.0 load.
The FE models were run by the National Crash Analysis Center - George Washington University (NCAC), and a cost teardown analysis of the model improvements were developed by Ludtke & Associates and reported to the agency under contract DTNH22-00-C-02008. A complete discussion of the results of these models is included in Chapter V. The added weight from the changes estimated by Ludtke is summarized in Tables V-1 through V-4 in Chapter V. To estimate the impact these changes would have on cg, NHTSA engineering staff examined the nature of the changes and estimated their location relative to the cg. A new cg was then calculated based on these changes.
This process and the resulting estimates are summarized in Table A-1. Table A-1 lists the baseline factors as well as the modified factors that result from our analysis.
| 3.0 Load Requirement | 2.5 Load Requirement | |||
|---|---|---|---|---|
| Chevy S-10 | Caravan | Neon | E-150 | |
| Track Width (mm) = | 1384.3 | 1612.9 | 1475.74 | 1770.38 |
| Baseline cg (inches) = | 23.07 | 26.57 | 20.59 | 31.3 |
| Modified cg (inches) = | 23.22 | 26.59 | 20.61 | 31.37 |
| Baseline cg (mm) = | 586.13 | 674.88 | 522.99 | 795.02 |
| Modified cg (mm) = | 589.87 | 675.43 | 523.58 | 796.75 |
| Baseline SSF = | 1.1809 | 1.1950 | 1.4109 | 1.1134 |
| Modified SSF = | 1.1734 | 1.1940 | 1.4093 | 1.1110 |
| Baseline Rollover Propensity = | 0.1970 | 0.1881 | 0.1087 | 0.2527 |
| Modified Rollover� Propensity = | 0.2020 | 0.1887 | 0.1090 | 0.2552 |
| Change in Rollover Propensity = | .0050 | .0006 | .0003 | .0025 |
Uncertainty and Caveats
These calculations illustrate a method that might be used to estimate potential impacts from weight shifts that affect cg. Unfortunately, the information from these four finite element models is of limited use in analyzing possible cg impacts for a number of reasons:
The importance of individual vehicle characteristics is apparent from the SSF model that drives this analysis. This is demonstrated in Figure A-1, which illustrates the relationship between SSF and the probability of rollover in single vehicle crashes. There is an obvious decrease in the rate of change in the slope of the curve as SSFs improve. This implies that vehicles with low SSFs experience larger changes in their rollover probability when their cg changes than do vehicles with higher SSFs. The practical result is that a given SSF change in a vehicle with a low SSF could have a much more significant impact than the same SSF change in a vehicle with a high SSF.
Figure A-1
To put this in perspective, NCAP SSF ratings for recent model vehicles were derived from a recent NHTSA study on historical trends in SSF ratings. [34] This study examined SSF trends from passenger vehicles for model years 1975-2003. The average SSF rating across all 2003 MY passenger cars and LTVs was 1.30. Based on the rollover probability formula, an increase of .01 in the SSF for a vehicle with a 1.30 SSF increases the probability of injury by .0036, i.e., by less than 4 tenths of a percent. By contrast, the Neon has an SSF of 1.41 and the E-150 has an SSF of 1.10. At these SSF levels, an increase of .01 SSF would increase the probability of injury by .0022 and .0110 respectively. The Neon thus experiences an impact that is about 60 percent of the fleet average while the E-150 experiences an impact that is 3 times as high as the fleet average. These relative impacts are shown graphically in Figure A-2.
Thus, all other things being equal, the Neon results would understate the impact on the fleet somewhat, but the E-150 results would greatly overstate the expected impact on the fleet. To determine the actual fleet impact on cg and SSF however, more specific data regarding vehicle changes is required. Unfortunately, although the SSF is known for a large sample of the fleet, the expected change in cg, and thus the change in SSF for the overall fleet, is unknown.
Figure A-2
Manufacturers generally strive to maintain or improve their NCAP ratings to help market their vehicles. The Agency believes that this concern over NCAP ratings would preclude a design strategy that unnecessarily increases cg and degrades SSF. Support for this conclusion can be found in recent vehicle designs. Table A-2 lists the SSF ratings and roof strength for recent model vehicles. The sample of vehicles in Table A-2 includes all vehicles for which both SSF and roof strength ratings were available. They are grouped with similar sized vehicles to show the ratings within similar groups. These data indicate that most recently designed vehicles with stronger roofs also have higher SSFs. It�s unclear whether this represents an overt design decision on the part of manufacturers or whether it is due to other factors, but it does demonstrate that current designs generally reflect both higher levels of roof strength and higher levels of rollover resistance. Manufacturers are thus experienced in designs that maintain both aspects of vehicle safety.
| Type | Vehicle | SSF | Strength to Weight Multiple (5" of plate displacement) |
|---|---|---|---|
| Small Car | 2003 Chevrolet Cavalier (4-door) | 1.35 | 2.9 |
| 2003 Ford Focus (Hatchback) | 1.30 | 2.7 | |
| Midsize Car | 2003 Mazda 6 | 1.46 | 3.4 |
| 2001 Ford Taurus | 1.43 | 2.0 | |
| 2002 Toyota Camry | 1.40 | 3.1 | |
| 2003 Chevrolet Impala | 1.36 | 3.1 | |
| Fullsize Car | 2001 Ford Crown Victoria | 1.51 | 2.0 |
| Minivan | 2004 Nissan Quest | 1.36 | 2.8 |
| 2004 Chrysler Pacifica | 1.30 | 2.2 | |
| 1997 Dodge Caravan | 1.20 | 2.6 | |
| 2003 Ford Windstar | 1.26 | 2.2 | |
| Small SUV | 2003 Subaru Forester | 1.24 | 4.7 |
| 2002 Honda CR-V | 1.16 | 3.0 | |
| 2004 Honda Element | 1.17 | 4.3 | |
| Midsize SUV | 2003 Kia Sorento | 1.14 | 2.0 |
| 2002 Nissan Xterra | 1.12 | 3.0 | |
| Fullsize SUV | 2003 Chevrolet TrailBlazer | 1.18 | 2.2 |
| 2002 Ford Explorer | 1.13 | 2.1 | |
| Oversize SUV | 2003 Ford Expedition | 1.17 | 2.4 |
| 2001 Chevrolet Tahoe | 1.14 | 2.6 | |
| Compact Pickup | 1998 Chevrolet S-10 | 1.15 | 2.8 |
| Fullsize Pickup | 2002 Dodge Ram 1500 Regular Cab Pickup | 1.24 | 2.4 |
| 2003 Ford F150 Regular Cab Pickup | 1.22 | 3.0 | |
| Fullsize Van | 1999 Ford E-150 | 1.11 | 1.9 |
| 2003 Chevrolet Express | 1.10 | 2.0 |
Hypothetical Fleet Impact
The 2 evaluated vehicles are not representative of the vehicle fleet and are thus insufficient to derive a reliable estimate of potential impacts of raising cg. To derive an estimate for the broader fleet, the other six vehicles that failed to meet the proposed 2.5 times vehicle weight standard will be examined together with the Neon and E-150. Although still a small sample, the eight vehicles together give a better cross section of vehicle types with their differing body characteristics.
| Compact Car | 97 Dodge Neon (FE model) |
| Mid Size Car | 01 Ford Taurus |
| Large Car | 01 Ford Crown Victoria |
| Large Pickup | 02 Dodge Ram 1500 |
| Full Size SUV | 03 Ford Expedition |
| Mid Size SUV | 02 Ford Explorer |
| Full Size Van | 99 Ford E-150 (FE model) |
| Full Size Van | 03 Chevy Express |
Since the 6 added vehicles do not have finite element models to assess their response to a higher standard, a number of assumptions must be made. These assumptions are:
Under these assumptions, each vehicle was examined and new cg estimates were established based on the revised weight distributions. The revised cg estimates were used to compute revised SSFs for each vehicle. These were then used to calculate the change in rollover crashes.
The 8 vehicles were split into a passenger car group and an LTV group, each representing predicted impacts on single vehicle crashes for their specific group only. Within each group, the individual vehicles were assumed to represent the fleet of vehicles in their size class (the 2 full sized vans were averaged for their category). The results that were derived from each vehicle were thus weighted according to the relative sales of their own� type/size category. [35] To stay consistent with the overall future sales assumptions used in the body of the analysis, passenger car and LTV results were then weighted together assuming sales of 8 million passenger cars and 9 million LTVs.
Table A-3 summarizes the process used to estimate changes in cg for each of the 8 vehicles. The basic relationship used to calculate the new cg is derived as follows:
cgn =� (w*cg+wa*r)/ (w+wa)
Where
In this algorithm, cg, w, and r are measured characteristics specific to each vehicle. Initial cg is measured using an inertial parameters measurement device, a two-axis pendulum that measures periods of oscillation. Added weight at roof level ( wa )is an estimate based on engineering judgment of the net impact of changes described in the finite element models for the Neon and E-150. These changes were examined to determine the extent to which structural changes might translate to weight added at the roof level. To the extent that these changes were cg neutral they were ignored. Structural changes that were not cg neutral were deflated to their equivalent values if spread solely at the roof level. This involved a level of engineering judgment. The proportion of total added weight that was judged to impact cg for the Neon was assumed for the other 2 passenger cars, and the proportion that was judged to impact cg for the E-150 was assumed for the other 4 LTVs.
| Vehicle | Weight (lbs.) |
CG (Height in.) |
Added Weight (lbs.) at Roof |
Roof Height |
New CG (Height in.) |
|---|---|---|---|---|---|
| Passenger Cars | |||||
| 97 Dodge Neon | 3514 | 20.59 | 2.2 | 58.1 | 20.61 |
| 01 Ford Taurus | 3393 | 21.70 | 1.9 | 56.1 | 21.72 |
| 01 Ford Crown Vic | 4000 | 21.39 | 1.2 | 56.8 | 21.40 |
| LTVs | |||||
| 99 Ford E-150 Van | 5416 | 31.30 | 7.6 | 79.8 | 31.37 |
| 03 ChevExpress Van | 5564 | 30.91 | 6.4 | 82.3 | 30.97 |
| 02 Ford Explorer | 4532 | 27.13 | 4.4 | 68.9 | 27.17 |
| 03 Ford Expedition | 5433 | 28.78 | 4 | 74.8 | 28.81 |
| 02 Dodge Ram 1500 | 4733 | 27.38 | 3.46 | 73.8 | 27.41 |
The new cgs listed in Table A-3 were used to calculate new SSFs, which were then used to calculate a revised rollover probability (the formulae for this process were discussed previously). Added rollovers were calculated by applying the change in rollover probability to the portion of police-reported single vehicle crashes that would be experienced by vehicles that do not meet the requirements of the proposal. As noted in Chapter V, based on annual sales volumes, passenger cars that failed to meet the 2.5 load factor proposal represent 30.7% of the tested fleet and LTVs that failed to meet the 2.5 load factor alternative represent 34.6% of the tested fleet. It is assumed that these same portions will apply to crash involvement for the specific vehicle types.
Table A-4 summarizes the calculated results for each of the 8 vehicles. The added rollover row represents full fleet impacts for the specific vehicle category (passenger cars or LTVs) that each vehicle belongs to. Within each category, the results (added rollovers) for each vehicle were weighted together based on the relative sales of vehicles in the size class represented by each vehicle to produce a separate estimated impact for passenger cars and LTVs. These two groups were then combined assuming annual sales of 8 million passenger cars and 9 million LTVs. This produced a fleet estimate of 267 added rollovers from cg shifts. This process and its results are summarized in Table A-5. The results indicate that higher cgs would produce 267 more rollover crashes. These crashes represent current non-rollover crashes that will become rollover crashes if the vehicle has a higher cg. To reflect this altered crash status, the more serious rollover injury profile was substituted for the current non-rollover injury profile for these cases (Table A-6). The difference represents the potential safety impact under each hypothetical case. Equivalent fatalities are calculated using the same factors described in the Cost Effectiveness chapter in the body of this report. The results indicate that added rollovers will cause 6 added fatalities or 8 added equivalent fatalities. When these impacts are deducted from the savings from added roof strength, the cost per equivalent fatality becomes $2.4 million - $4.2 million (summarized in Table A-5). Note that the sample of vehicles used for this analysis had SSFs which average 1.28. This is below the fleet average of 1.30, which means that the vehicles used in this analysis experienced impacts from cg changes that overstate the results that would be expected from the full vehicle fleet.
| Taurus | Crown Vic | Neon | E-150 | Express | Explorer | Expedition | Ram 1500 | |
|---|---|---|---|---|---|---|---|---|
| P.R. Single Vehicle Crashes | 800000 | 800000 | 800000 | 900000 | 900000 | 900000 | 900000 | 900000 |
| Crashes Involving Failed Vehicles | 245247 | 245247 | 245247 | 311805 | 311805 | 311805 | 311805 | 311805 |
| Track Width (mm) = | 1572.26 | 1635.76 | 1475.74 | 1770.38 | 1734.82 | 1557.02 | 1709.42 | 1724.66 |
| Baseline cg (inches) = | 21.7 | 21.39 | 20.59 | 31.3 | 30.91 | 27.13 | 28.78 | 27.38 |
| Modified cg (inches) = | 21.72 | 21.4 | 20.61 | 31.37 | 30.97 | 27.17 | 28.81 | 27.41 |
| Baseline cg (mm) = | 551.18 | 543.31 | 522.99 | 795.02 | 785.11 | 689.1 | 731.01 | 695.45 |
| Modified cg (mm) = | 551.69 | 543.56 | 523.49 | 796.8 | 786.64 | 690.12 | 731.77 | 696.21 |
| Baseline SSF = | 1.4263 | 1.5054 | 1.4109 | 1.1134 | 1.1048 | 1.1297 | 1.1692 | 1.2400 |
| Modified SSF = | 1.4249 | 1.5047 | 1.4095 | 1.1109 | 1.1027 | 1.1281 | 1.1680 | 1.2386 |
| Baseline Rollover % = | 0.1054 | 0.0909 | 0.1087 | 0.2527 | 0.2619 | 0.2368 | 0.2050 | 0.1641 |
| Modified Rollover % = | 0.1056 | 0.0910 | 0.1090 | 0.2553 | 0.2643 | 0.2383 | 0.2058 | 0.1647 |
| Added Equivalent Fleet Rollovers = | 68 | 27 | 73 | 809 | 745 | 481 | 269 | 200 |
| Vehicle | Vehicle Type | Weight | Rollover Impact | Aggregate |
|---|---|---|---|---|
| 97 Dodge Neon | Compact Cars | 38.52% | 73 | 28.28 |
| 01 Ford Taurus | Mid Size Cars | 50.39% | 68 | 34.19 |
| 01 Ford Crown Vic | Large Cars | 11.09% | 27 | 3.01 |
| Total Passenger Cars | 100.00% | 65.48 | ||
| 02 Ford Explorer | Mid SUV | 80.50% | 481 | 387.53 |
| 03 Ford Expedition | Full SUV | 4.01% | 269 | 10.78 |
| 02 Dodge Ram 1500 | Large Pickup | 12.72% | 200 | 25.39 |
| 99 E-150 and 03 Express | Full Van | 2.78% | 777 | 21.58 |
| Total LTVs | 100.00% | 445.28 | ||
| Weighted Average Increased Rollovers, PCs and LTVs | 266.6 | |||
| Added Fatalities = | 5.7 | |||
| Added Equivalent Fatalities = | 7.8 | |||
| Added Equivalent Fatalities (3%) = | 6.4 | |||
| Added Equivalent Fatalities (7%) = | 5.1 | |||
| Approach A | Approach B | |||
| Net Equivalent Fatalities� (3%) = | 26.0 | 39.2 | ||
| Net Equivalent Fatalities� (7%) = | 20.9 | 31.4 | ||
| Cost Per Equivalent Fatality (3%) = | $3.67 | $2.44 | ||
| Cost Per Equivalent Fatality (7%) = | $4.22 | $2.80 | ||
| Rollover | Non-Rollover | Rollover | Non-Rollover | Net Impact | Fatality Equivalence Factor |
Equivalent Fatalities |
|
|---|---|---|---|---|---|---|---|
| MAIS 0 | 42.83% | 72.13% | 152 | 257 | -104 | ||
| MAIS 1 | 43.45% | 22.92% | 155 | 82 | 73 | 0.0031 | 0.2 |
| MAIS 2 | 7.98% | 3.17% | 28 | 11 | 17 | 0.0458 | 0.8 |
| MAIS 3 | 3.08% | 1.07% | 11 | 4 | 7 | 0.0916 | 0.7 |
| MAIS 4 | 0.40% | 0.17% | 1 | 1 | 1 | 0.2153 | 0.2 |
| MAIS 5 | 0.20% | 0.10% | 1 | 0 | 0 | 0.7124 | 0.3 |
| Fatality | 2.06% | 0.45% | 7 | 2 | 6 | 1 | 5.7 |
| Total | 100.00% | 100.00% | 356 | 356 | 0.0 | 7.8 |
Source:� 1998-2003 NASS CDS data, 1982-86 NASS non-CDS cases, 2003 FARS
Potential Countermeasures
Ultimately, the impact that revisions to FMVSS 216 will have on the frequency of rollover crashes will depend on how manufacturers choose to address the issue. As noted above, there are a number of weight shifting options that could be used to maintain or improve current cgs. These include:
Removing weight from above the center of gravity would likely be the least costly approach, but could, in some instances, create design challenges. Adding weight below the center of gravity would be relatively simple, but could prove costly and might clash with corporate fuel economy strategies. Substituting high strength alloys and other light-weight materials would probably add cost, but would allow for minimal weight impacts. Minor modifications to the vehicle�s track width would be easily accomplished within normal design cycles given enough leadtime. Changes in OEM tire characteristics would be a simple short run solution.
Regardless of which approach manufacturers choose, the challenge they face for this standard is similar to that which they face with any redesign of their vehicle � to maximize the vehicles performance and safety using the most efficient design and production methods.
None of these options has been evaluated in the body of this analysis because NHTSA does not feel there is enough information to determine the course of action that manufacturers will take, nor do we have cost data for design changes other than those specified by Ludtke. However, the impact of one option � adding weight below the cg to offset that added above, will be estimated here to illustrate the potential impact and practicability of a strategy that prioritizes maintaining the vehicle�s current rollover characteristics. The agency does not necessarily believe that manufacturers would choose this method. In fact, manufacturers would likely seek to avoid its cost and weight impacts. However, it is presented to demonstrate that strategies that maintain existing rollover characteristics are practicable within the context of this rule.
To estimate the impact of this strategy, it was assumed that weight is added below the cg to offset that added above the cg. In addition, it was assumed that the added weight below the cg would take the form of basic steel ballast added to the vehicle�s frame during the normal redesign cycle. It would thus result in a slightly heavier frame than would otherwise have been produced for the redesigned vehicle. Under these assumptions, the added cost and fuel economy impacts from additional weight were calculated. Revised costs were then calculated by adding the original costs to the marginal costs of maintaining cg levels and new cost effectiveness values were derived.
The amount of weight added below the cg was determined by assuming that ballast would be added to the frame structure and comparing the product of the weight added to the roof and distance from cg of that added weight to the distance from cg of the frame structure. The formula to derive these weights was:
Wn =� (r-cg*w)/(cg-g)
Where
The results of this analysis are summarized in Table A-7. The heavier weights required to offset the added weight at the roof are a function of the cg being closer to the frame area where ballast would be added than to the roof where the reinforcement weight was added. The average affected passenger car would require 4.56 lbs. of added weight to maintain cg, while the average LTV would require 10.24 lbs.
These values were applied to the present value algorithm described in Chapter 5 to derive the present value of added lifetime fuel cost that would result from this weight. Table A-8 shows the results of these calculations. The added weight would increase lifetime fuel costs for the entire affected vehicle fleet by from $45 million to $57 million.��
| Vehicle | CG Height |
Added Weight |
Roof Height |
Ground Clearance |
Counterbalance Weight (lbs.) |
|---|---|---|---|---|---|
| 97 Dodge Neon | 20.59 | 2.2 | 58.1 | 5.85 | 5.60 |
| 01 Ford Taurus | 21.70 | 1.9 | 56.1 | 6 | 4.16 |
| 01 Ford Crown Vic | 21.39 | 1.2 | 56.8 | 6 | 2.76 |
| Average, All Passenger Cars | 4.56 | ||||
| 99 Ford E-150 Van | 31.30 | 7.6 | 79.8 | 7.1 | 15.23 |
| 03 Chev Express Van | 30.91 | 6.4 | 82.3 | 6.9 | 13.70 |
| 02 Ford Explorer | 27.13 | 4.4 | 68.9 | 8.5 | 9.87 |
| 03 Ford Expedition | 28.78 | 4 | 74.8 | 8.9 | 9.26 |
| 02 Dodge Ram 1500 | 27.38 | 3.46 | 73.8 | 8.1 | 8.33 |
| Average, All LTVs | 10.24 | ||||
| Weighted Average Weight Increase, Affected PCs and LTVs | 7.57 | ||||
| Passenger Car Failure Rate | 30.66% | ||||
| LTV Failure Rate | 34.65% | ||||
| Average Weight Increase Across Entire Fleet (lbs.) | 2.54 | ||||
| PDV Cost/Vehicle (2002$) | Sales | Failure Rate | Affected Vehicles | Total Fuel Cost (2003$)* | |
|---|---|---|---|---|---|
| 7% Discount Rate | |||||
| LTV | $10.55 | 9000000 | 0.3465 | 3118500 | $33,502,601 |
| PC | $4.63 | 8000000 | 0.3066 | 2452800 | $11,564,409 |
| Total | $7.76 | 17000000 | 0.324 | 5508000 | $45,067,010 |
| 3% Discount Rate | |||||
| LTV | $13.46 | 9000000 | 0.3465 | 3118500 | $42,743,603 |
| PC | $5.65 | 8000000 | 0.3066 | 2452800 | $14,112,076 |
| Total | $9.78 | 17000000 | 0.324 | 5508000 | $56,855,679 |
| *� Adjusted to 2003 dollars based on GDP implicit price deflator. | |||||
Added design costs were estimated assuming a steel price of 40 cents per pound. Because the weight is added as a slightly heavier frame during the normal redesign cycle, there is no added assembly labor. The design cost consists of the added material cost plus the normal markup for overhead and profit (1.51). These estimates are summarized in Table A-9.
The cost of an average affected passenger car would increase an additional $2.75 and the cost of an average affected LTV would increase by an additional $6.19. Across the entire new vehicle fleet, the average cost increase would be $1.53. The total increase due to design costs to maintain cg levels for the fleet would be $26 million.
| Vehicle | Added* Weight (lbs.) | Cost/lb. | Total Material Cost | Total Unit Cost |
|---|---|---|---|---|
| Passenger Cars | ||||
| 97 Dodge Neon | 5.6 | $0.40 | $2.24 | $3.38 |
| 01 Ford Taurus | 4.16 | $0.40 | $1.66 | $2.51 |
| 01 Ford Crown Vic | 2.76 | $0.40 | $1.10 | $1.67 |
| Average, All Passenger Cars | $2.75 | |||
| LTVs | ||||
| 99 Ford E-150 Van | 15.2 | $0.40 | $6.08 | $9.18 |
| 03 ChevExpress Van | 13.7 | $0.40 | $5.48 | $8.27 |
| 02 Ford Explorer | 10.45 | $0.40 | $4.18 | $6.31 |
| 03 Ford Expedition | 9.26 | $0.40 | $3.70 | $5.59 |
| 02 Dodge Ram 1500 | 8.33 | $0.40 | $3.33 | $5.03 |
| Average, All LTVs | $6.19 | |||
| Weighted Average Price Increase, Affected PCs and LTVs | $4.57 | |||
| Passenger Car Failure Rate | $0.31 | |||
| LTV Failure Rate | $0.35 | |||
| Average Price Increase Across Entire Fleet | $1.53 | |||
| Total Fleet Price Increase | $26,045,878 | |||
The overall impact of these scenarios on cost effectiveness is indicated in Table A-10. The results indicate that maintaining cg using this approach would increase the cost per equivalent fatality for the proposal to a range of $4.0-$6.1 million from its current $2.1 - $3.4 million. Thus even with this costly ballast approach, the possible outcomes fall within a range that could be considered acceptable, given the range of estimates that exist for valuing fatality prevention [36].
However, as noted above, this is perhaps the most costly and least likely approach that manufacturers could take to resolve this issue. It is more likely that design solutions will be found that can achieve a neutral impact on cg for significantly less than the simple but costly approach demonstrated here.
| Cost (millions) | Equivalent Fatalities | Cost Per Equivalent Fatality (millions) |
|||
|---|---|---|---|---|---|
| Approach | Approach | ||||
| A | B | A | B | ||
| 2.5 Load Factor | |||||
| Discounted @ 3% | $180.3 | 32.4 | 45.6 | $5.56 | $3.96 |
| Discounted @ 7% | $159.0 | 26.0 | 36.5 | $6.12 | $4.35 |
Discussion
Changes made to meet increased roof strength requirements could result in very minor shifts in the center of gravity of passenger vehicles. For the 2 FEM models that were measured to the proposed force level, the predicted change in cg is below the measurable level of accuracy for center of gravity. We are physically unable to accurately determine cgs within approximately .5% of the measured height, [37] which is the equivalent of roughly plus or minus 3 mm. The predicted changes in cg were less than 2 mm for the E-150 and less than 1 mm for the Neon � roughly the width of a pencil line. Nonetheless, when applied to the Agency�s SSF rollover probability model and projected across the full vehicle fleet, these tiny shifts result in an analytical prediction that a small number of crashes will become rollovers, and that a small number of fatalities and injuries will occur which will offset a portion of the benefits from increased roof strength. This result was based on very sparse data obtained from finite element models for 2 vehicles, a large van and a compact passenger car, neither of which adequately represents the scope of designs in the new car fleet. Further, the design changes used in the finite element models did not reflect a goal of maintaining cg. The agency believes there is a great deal of uncertainty regarding the actual changes that manufacturers will initiate in response to this rule, but there are numerous ways to address both roof strength and rollover propensity simultaneously and there is evidence from current NCAP ratings that manufacturers are routinely doing so. Manufacturers generally strive to maintain or improve their NCAP ratings to help market their vehicles. The Agency believes that this concern over NCAP ratings would preclude a design strategy that unnecessarily increases cg and degrades SSF.
Ultimately the impact that revisions to FMVSS 216 will have on the frequency of rollover crashes will depend on how manufacturers choose to address the issue. Regardless of which approach manufacturers choose, the challenge they face for this standard is similar to that which they face with any redesign of their vehicle � to maximize the vehicle�s performance and safety using the most efficient design and production methods. The agency believes that manufacturers would adopt a strategy that prioritizes maintaining or improving the vehicle�s current rollover characteristics. The agency seeks comment on this issue, and specifically seeks information regarding the nature, cost, and weight of design changes that manufacturers would employ to improve roof strength.
[1] The roof over the front seat area means the portion of the roof, including windshield trim, forward of a transverse plane passing through a point 162 mm rearward of the seating reference point of the rearmost front outboard seating position.
[2] For purposes of this notice, the term "light truck" includes MPVs, trucks, and buses.
[3] Extended FMVSS No. 216 tests continue to crush the roof beyond the requirements of the standard.
[4] Near side is the side toward which the vehicle begins to roll and the far side is the trailing side of the roll.
[5] Parenteau, Chantal, Madana Gopal, David Viano. "Near and Far-Side Adult Front Passenger Kinematics in a Vehicle Rollover."� SAE Technical Paper 2001-01-0176, SAE 2001 World Congress, March 2001.
[6] Bahling G.S., R.T. Bunford, G.S. Kaspzyk, E.A. Moffat, K.F. Orlowaki, and J.E. Stocke, "Rollover and Drop Tests � The Influence of Roof Strength on Injury Mechanics Using Belted Dummies,"� SAE Paper 902314, Society of Automotive Engineers, Warrendale, PA, 1990.
[7] Huelke, D.F., J.C. Marsh, and H.W. Sherman, "Analysis of Rollover Accident Factors and Injury Causation," 16th Conference of the American Association of Automotive Medicine, 1972.
[8] MacKay, G.M. and I.D. Tampan, "Field Studies of Rollover Performance", SAE 700417, 1970 International Automobile Safety Conference Compendium, P-30, Society of Automotive Engineers, 1970.
[9] Huelke, D.F., T.E. Lawson, R. Scott, J.C. Marsh, "The Effectiveness of Belt Systems in Frontal and Rollover Crashes." SAE 770148, 1977.
[10] Partyka, S. "Rollovers and Injury on the NCSS File." NHTSA, 1978
[11] Partyka, S.C. "Roof Intrusion and Occupant Injury in Light Passenger Vehicle Towaway Crashes." Office of Vehicle Safety Standards, National Highway Traffic Safety Administration, Washington D.C., 1992.
[12] Rains, G.C. and J.M. Kanianthra, "Determination of the Signifivcance of Roof Crush on Head and Neck Injury to Passenger Vehicle Occupants in Rollover Crashes, SAE 950655, Detroit Michigan, 1995.
[13] Austin, Rory, Hicks, Maurice, Summers, Stephen, "The Role of Post-Crash Headroom in Predicting Roof Contact Injuries to the Head, Neck, or Face During FMVSS 216 Rollovers", NHTSA, 2003, internal report, not yet published.
[14] Complete ejections were excluded. Partial ejections were included.
[15] For fatalities the restriction was only that the fatal injury be at the maximum level, but �not necessarily the single injury at the level. See more detailed discussion under "Target Populations:.
[16] MSN Autos provides vehicle specifications to aid consumers in the purchase of new and used vehicles. The web site, http://autos.msn.com, is maintained by Microsoft Corporation, Redmond, WA.
[17] The two cases with large weights leads to a tremendously large confidence interval.
[18] Head contact was estimated using string pot measurements in the first series of vehicles, but dummy contact measurements with the second set of tests. See Chapter II for further discussion.
[19] Austin et al
[20] ADD Jenny�s REPORT
[21] Wang, J.S. and Blincoe, L.J., BELTUSE Regression Model Update, U.S.DOT, NHTSA, Washington D.C., June 2001. and� Wang, J.S. and Blincoe, L.J., Belt Use Regression Model � 2003 Update, USDOT, NHTSA, Washington D.C., DOT-HS-809-639, May, 2003�
[22]�� Kahane, Charles J. , Fatality Reduction by Safety Belts for Front-Seat Occupants of Cars and Light Trucks, NHTSA, U.S. DOT, Washington, D.C., DOT HS 809 199, December 2000.
[23] Winnicki, John, Estimating the Injury Reducing Benefits of Ejection-Mitigating Glazing, NHTSA, USDOT, DOT HS 808 369, February 1996.
[24] DOE Energy Information Administration, Annual Energy Outlook 2001, Table A3, Energy Prices by Sector.
[25] "Effectiveness and Impact of Corporate Average Fuel Economy (CAFE) Standards", National Research Council, July 2001, Pages 5-5 to 5-6.
[26] "Oil Imports: An Assessment of Benefits and Costs", P.N. Leiby, D.W. Jones, T.R. Curlee, and L. Russell, 1997, ORNL-6851, Oak Ridge National Laboratory, Oak Ridge, Tenn.
[27] Blincoe et al
[28] L. Blincoe, A. Seay, E. Zaloshnja, T. Miller, E. Romano, S. Luchter, R. Spicer, (May 2002) "The Economic Impact of Motor Vehicle Crashes, 2000". Washington D.C.: National Highway Traffic Safety Administration, DOT HS 809 446.
[29] "Revised Departmental Guidance, Treatment of Value of Life and Injuries in Preparing Regulatory Evaluations", Memorandum from Kirk K. Van Tine, General Counsel and Linda Lawson, Acting Deputy Assistant Secretary for Transportation Policy to Assistant Secretaries and Modal Administrators, January 29, 2002.
[30] For example, Miller, T.R. (2000): "Variations Between Countries in Values of Statistical Life", Journal of Transport Economics and Policy, 34, 169-188.
[31] 49 U.S.C. 105 and 322; delegation of authority at 49 CFR 1.50.
[32] NHTSA estimates that about one third of all vehicles would require changes to meet the proposed standard.
[33]�This cg analysis addresses only single vehicle crashes because the formula derived for SSF is specific to that group. Basically, the crash dynamics of multi-vehicle crashes are so different that we do not feel that it would be appropriate to assume a similar relationship for both single and multi-vehicle crashes. Prior impact is the likely cause of rollover in 97 percent of fatal multi-vehicle crashes that result in rollovers (i.e., impact occurs prior to the rollover in 97 percent of cases), and this would obscure any direct relationship to subtle changes in cg characteristics. Only a small portion of rollover fatalities (16%) occur in multi-vehicle crashes, so even in the unlikely event that there is some minor influence from cg, it would not have a significant impact on fatalities.
[34] Walz, Marie C., Trends in the Static Stability Factor of Passenger Cars, Light Trucks, and Vans, NHTSA, U.S. Department of Transportation, Washington, D.C., DOT-hs-809-868, June, 2005.
[35] Relative weights were derived from the most recently available sales data for the period covering January through August 2005 obtained online ( www.autonews.com) from the Automotive News Data Book.
[36] DOTs current official estimate for the value of a life is $3 million. However, this estimate is currently under review in light of research indicating that higher values may be appropriate. Currently, OMB recommends using a value between $1 and $10 million. NHTSA examines $5.5 million, the median value in this range, for purposes of uncertainty analysis in its most significant rules.
[37] See An Overview of a Vehicle Inertia Measurement Facility by Heydinger, Coovert, Lawrence, Durisek, and Guenther, 27th International Symposium on Automotive Technology and Automation, ISATA Paper 94SF034, October, 1994