I.  Background

A.  Existing Standard

Standard No. 301, Fuel system integrity, sets performance requirements for the fuel systems of vehicles with a gross vehicle weight rating (GVWR) of 4,536 kg (10,000 pounds) or less. The standard, which was issued in the 1970s, limits the amount of fuel spillage from fuel systems of vehicles during and after being subjected to a frontal, rear, or side impact test.

In the frontal impact test, the test vehicle is driven forward into a fixed barrier at 48 km/h (30 mph). In the rear impact test, a 1,814 kg (4,000 pound) barrier moving at 48 km/h (30 mph) is guided into the full width of the rear of a stationary test vehicle. In the side impact test, a 1,814 kg (4,000 pound) barrier moving at 32 km/h (20 mph) is guided into the side of a stationary test vehicle. The standard sets three separate limits on fuel spillage from crash-tested vehicles:  28 grams (1 ounce) by weight, during the time period beginning with the start of the impact and ending with the cessation of vehicle motion; a total of 142 grams (5 ounces) by weight during the 5-minute time period beginning with the cessation of vehicle motion; and 28 grams (1 ounce) by weight during any 1-minute interval in the 25-minute period beginning with the end of the 5-minute period.

Similar fuel spillage limits apply to vehicles tested in accordance with the standard’s static rollover test procedure. [1]   The rollover test is conducted after frontal, rear, and side impact tests.

B.  Safety Problem

Preserving fuel system integrity in a crash is critical to preventing occupant exposure to fire. Although vehicle fires are relatively rare events (occurring in less than 1 percent of vehicles in towaway crashes), they tend to be severe in terms of the number of casualties caused. According to an analysis of data in the agency’s Fatality Analysis Reporting System (FARS) in 2001, 3.5% percent (1,449 fatalities) of light vehicle occupant fatalities occurred in crashes involving fire. [2] Overall, the fire itself was deemed to be the most harmful event in the vehicle for about 24 percent (341) of these fatalities.

An analysis of 1993-2001 National Automotive Sampling System (NASS) data indicated that each year an average of about 15,820 occupants were exposed to a post-crash fire in passenger cars and light vehicles (vans, pickup trucks, and multipurpose passenger vehicles) with a GVWR of 4,536 kg (10,000 pounds) or less that were towed away after the fire. Of those occupants, about 736 (6 percent) received moderate or severe burns (AIS 2 and greater). Three-quarters of those with moderate and more severe burns had second or third degree burns over more than 90 percent of the body. Moreover, the agency notes that maximum-severity (AIS 6) burns are nearly always fatal. These statistics underscore the importance of preserving fuel system integrity in a crash in order to prevent vehicle fires.

II.  1995 Advance Notice of Proposed Rulemaking

On April 12, 1995, NHTSA published an Advance Notice of Proposed Rulemaking (ANPRM) announcing the agency’s plans to consider upgrading Standard No. 301. [3]  The agency explained that it was considering using a three-phase approach to upgrade the requirements of the standard. Phase 1 would focus on requirements for component performance (e.g., fuel tanks, fuel pumps, and electrical systems); Phase 2 would address system performance (e.g., shutting down fuel supply and potential ignition sources in the event of a breach in the fuel system); and Phase 3 would address issues related to environmental and aging effects (e.g., the potential relationship of vehicle aging to fire occurrence). The agency sought comment on this approach as well as several other issues.

NHTSA received comments from component and vehicle manufacturers, industry associations, consumer advocacy organizations, and other organizations. After reviewing these comments and further analysis, the agency made the following decisions.

First, after examining the effectiveness of fuel pump shut-off devices in reducing post-crash vehicle fires, the agency decided not to pursue rulemaking with respect to fuel system component performance. The agency’s review of NASS data did not reveal a significant difference in the rate or severity of post-crash fire occurrence in vehicles with and vehicles without fuel pump shut-off devices. Research conducted under the General Motors (GM) C/K settlement agreement [4] confirmed this finding during crash testing with and without fuel pump shut-off devices. During crash testing, there was no difference in the rate of fuel leakage or severity of post-crash fire occurrence between vehicles equipped with shut-off switches (Ford) and those without (GM, Chrysler and Honda).

Second, the agency decided not to pursue rulemaking related to environmental and aging effects. The agency agreed with vehicle manufacturer comments that further studies were needed to define the problems associated with environmental and aging effects and determine whether rulemaking would be appropriate to address them. The agency stated that it might revisit this issue upon further study. As part of the GM settlement, GM contracted with Southwest Research Institute to conduct research on the environmental factors and aging effects on fuel system components. This report showed some effects of corrosion on metal components and some effects of hot arid conditions on rubber components, and little effect on plastic components. The findings were inconclusive, but did not indicate serious problems affecting fuel system crash performance. No further agency action is planned at this time. [5]  

Third, the agency decided to investigate the feasibility and practicability of upgrading Standard No. 301’s rear and side impact requirements. The agency reviewed real world crash data to determine what types of rear impact crashes resulted in "moderate," "severe," and "very severe" fires. [6]   Next, the agency analyzed the data to determine whether it was the fire or the impact of the crash that caused the fatalities and injuries in the fire-related crashes. NHTSA then examined the data to determine the characteristics of rear crashes that were causing fire-related fatalities and injuries and developed a new crash test procedure to simulate the most frequent crash scenario that leads to fire and fire-related fatalities and injuries in rear impact crashes. The agency then performed seventeen crash tests using the new crash test procedure. [7]  

III.  2000 Notice of Proposed Rulemaking

A.  Proposed Rear Impact Test Procedure

After reviewing the comments on the 1995 ANPRM and analyzing the real world crash data and data from the seventeen crash tests with the new crash test procedure, the agency published a Notice of Proposed Rulemaking (NPRM) on November 13, 2000. [8]   In the NPRM, the agency tentatively concluded that the proposed rear impact test procedure would reduce fire-related fatalities and injuries from rear impact crashes. Thus, the agency proposed to replace Standard No. 301’s current rear impact test procedure with one that would specify impacting the rear of the test vehicle at 80 ± 1 km/h (50 mph) with a 1,368 kg (3,015 pound) moving deformable barrier (MDB) at a 70 percent overlap with the test vehicle. That barrier is very similar to that used under Standard No. 214, Side impact protection, in dynamic side impact testing except that the face of the MDB used in rear impact testing under Standard No. 301 would be 50 mm (2 inches) lower than the face of the Standard No. 214 barrier to simulate pre-crash braking. [9]

The agency noted that the proposed test procedure would simulate a type of rear vehicle-to-vehicle collision that can result in post-crash fire in an otherwise survivable crash:  a high speed offset rear strike to the vehicle that results in fuel leakage from a breach in the fuel system and, potentially, a rapidly spreading fire that results in fatalities and injuries. The agency also noted that NASS estimates show that the majority of fatal and nonfatal occupant burn injuries in rear impact crashes occurred in crashes in the 34 to 48 km/h (21 to 30 mph) delta-v range. The agency stated that the elements of the proposed offset rear impact test procedure were accordingly chosen to simulate vehicle-to-vehicle crashes with a delta-v range of 32 to 48 km/h (20 to 30 mph).

The agency tentatively concluded that the proposed offset rear impact test procedure was practicable. The agency stated:

Crash test results indicate that large, medium, and small vehicles could be designed to meet the standard under the proposed upgraded rear impact procedure. In those tests, some small as well as large existing light-duty vehicles already meet the proposed upgrade. Several larger light-duty vehicles, including passenger cars, multipurpose passenger vehicles, and light trucks, all passed the proposed upgrade. In addition, several small vehicles, the Mazda Miata, Chevrolet Metro, Nissan Sentra, and Honda Civic, passed the proposed upgrade. While we are aware that some existing smaller vehicles leaked fuel when tested under the proposed upgraded test procedure (e.g., the 1996 Suzuki Sidekick, Dodge Neon, and Geo Prizm, and the 1998 Chevrolet Cavalier, VW Jetta, and Ford Escort), we believe that relatively minor, inexpensive design changes would correct the vast majority of the failures. [10]   For example, the fuel lines in the Dodge Neon could be rerouted, and the area on top of the tank around the fuel sender unit plastic sealing plate could be reinforced on the VW Jetta. [11]

NHTSA did not propose to require manufacturers to place each vehicle’s fuel tank forward of the rear axle, as suggested by Advocates for Highway and Auto Safety (Advocates) in its comment on the ANPRM, because the agency believed such a requirement would be unnecessary and too design restrictive. The agency noted that the fuel tank of the 1996 Ford Mustang, which passed the proposed upgraded test procedure, is located behind the rear axle. The agency stated that this test demonstrated that structural and component designs are more critical factors than fuel tank location in maintaining fuel system integrity.

NHTSA also did not propose to use a heavier barrier (e.g., a 4,000-pound barrier) to simulate impacts by light trucks and sport utility vehicles, again as suggested by Advocates, because in an 80 km/h (50 mph) rear impact offset crash test, a 3,015-pound barrier effectively reproduces the damage profile seen in real world crashes that most often lead to fires. The agency stated that if a heavier barrier were used, the proposed rear impact crash test would no longer reproduce that profile. The agency also noted that it had conducted its research crash tests with a 3,015-pound barrier, and that further research and development would have to be conducted before a heavier barrier could be proposed for use in any test procedure.

B.  Proposed Side Impact Test Procedure

NHTSA proposed to replace the current lateral (side) impact crash test in Standard No. 301 with the side impact crash test currently specified in Standard No. 214. The Standard No. 214 side impact crash test specifies that a stationary vehicle be struck on either side by a 1,368 kg (3,015 pound) MDB moving at a speed of 54 km/h. [12]  

The agency reasoned that test analyses show that the Standard No. 214 side impact crash test exposes a tested vehicle to higher crush energy and crash forces, and to greater changes in velocity, than the existing Standard No. 301 side test. Test data also show the Standard No. 214 test exposes the fuel system components to greater forces.

Moreover, the agency reasoned that replacing the Standard No. 301 side test with the Standard No. 214 side impact test would reduce certification testing costs for manufacturers because they would only have to conduct one type of side impact test instead of two. The agency also noted that commenters on the ANPRM supported this change, stating that the change would be beneficial from both a safety and a cost perspective.

C.  Door System Integrity

In the NPRM, the agency also stated that it was considering adding a post-crash door openability test requirement to Standard No. 206. [13]   NHTSA noted that NASS data indicate that potential escape from a post-crash vehicle fire was made more difficult for occupants with moderate or more serious burns because, among other reasons, they were sitting next to a door that was jammed shut by crash forces. The agency also noted that real-world crash reports indicate that there were instances in which fire suddenly started several minutes after the vehicle was impacted. Thus, the agency concluded that it is critical that occupants be able to exit the vehicle quickly and easily after a crash that could lead to a fire. The agency requested comment on whether such a requirement was necessary and, if so, what type of requirements would be appropriate, objective, and repeatable.

D.  Lead Time

NHTSA proposed a lead time of three years for the proposed upgraded rear impact test and one year for the change to the Standard No. 214 side impact test. The agency stated that a three-year lead time appeared to be necessary for the proposed upgraded rear impact test because: (1) all of a manufacturer’s makes and models would have to be tested under the upgraded test to determine compliance; and (2) for those vehicles that did not comply, countermeasures would have to be incorporated into designs and then implemented in engineering and manufacturing. The agency stated that only one year of lead time was needed for the new side impact test because few, if any, design changes would be necessary.

NHTSA stated that between the date the final rule was issued and the date it took effect, manufacturers would be allowed the option of certifying vehicles under the existing Standard No. 301 tests or under the new tests. However, manufacturers would have to irrevocably select a test when they certified the vehicle.

E.  Costs and Benefits

The agency prepared a Preliminary Regulatory Evaluation (PRE) describing the costs and benefits of the proposed upgraded test procedures. [14]   NHTSA estimated that the average cost for vehicles that need to be modified to comply with Standard No. 301’s requirements under the proposed test procedures would be $5 per vehicle. The agency also estimated that 46 percent of the vehicle fleet would have to be so modified. [15]   Since approximately 15.2 million vehicles are sold in the United States each year, the agency estimated that the total cost of the proposed rule would be $35 million each year.

NHTSA estimated that the proposed rule would save from 8 to 21 lives annually, once all vehicles on the road meet Standard No. 301’s requirements under the proposed upgraded test procedures.

F.  Request for Comments on Additional Issues

In the NPRM, the agency also requested comments on several issues. The questions are repeated below.

1. Are there any real-world data, other than the data that the agency has already analyzed for this proposed upgrade, that may better describe the relationship between the risk of occupant injury due to fire and crash severity?

2. Vehicle manufacturers. How many of your vehicle models would need some redesign to comply with the proposed offset rear impact and side impact test procedures? Describe the type and extent of design changes. What costs would be associated with those redesigns?  Would you have any significant problems completing necessary redesigns within the three-year lead time? If so, please identify those problems and indicate how much lead time you would need.

3. What impact would the proposed changes have on vehicle safety?

4. Are the proposals sufficient and appropriate for the different sizes and types of vehicles?

5. In the various crash tests that were performed during the research for this rulemaking, the values of head and neck injury criteria measured by the responses of the two front Hybrid III anthropomorphic test devices were much higher than acceptable thresholds. Direct contact of the head of the dummy with the interior of the vehicle compartment, which occurred when the front seat rotated backward excessively due to the rear impact, contributed to these high values. These high values raise concerns about head and neck protection of the occupants. The rear impact testing also raised concerns about the seat back strength, as most seat backs collapsed in those tests. What do the high HIC values and neck loadings registered by the test dummies in those tests indicate about the real world potential for trauma injury to vehicle occupants in rear impacts?  Could future vehicles be designed to provide both the improved fuel system integrity necessary to meet the more stringent requirements proposed in this NPRM and, at the same time, provide improved occupant protection in such impacts?

6. How do seat back failures influence the injury potential in rear impacts?  Please provide data and other information that would aid the agency in determining the need for improving seat back strength and the appropriate requirements for doing so.

7. Should the agency require vehicles to retain fuel system integrity in tests with 5^th percentile female dummies, as well as with 50^th percentile male dummies, as is currently required?

8. NHTSA is proposing to eliminate the second sentence in S7.1.6(b) from Standard No. 301. That sentence reads:  "If the weight on any axle, when the vehicle is loaded to unloaded vehicle weight plus dummy weight, exceeds the axle’s proportional share of the test weight, the remaining weight shall be placed so that the weight on that axle remains the same."  Given the specifications in S7.1.6(a) concerning the placement of rated cargo and luggage capacity weight in the luggage area and the placement of dummies, is the second sentence in S7.1.6(b) needed for conducting Standard No. 301 compliance tests?

9. For the rear offset MDB test conditions, the agency is proposing that the barrier be the same as the one shown in Figure 2 of Standard No. 214 and specified in 49 CFR Part 587, with one exception. The exception is that the face of the barrier would be positioned in the rear impact test so that it is 50 mm (2 inches) lower than the barrier face height specified in the current Figure 2 of Standard No. 214. [16]

10. With respect to side impact crashes that result in fire, this proposal to upgrade Standard No. 301 addresses vehicle-to-vehicle crashes. There are approximately two to eight times as many side collision fires (depending on vehicle type) when the object struck is another vehicle compared to a narrow object such as a pole. However, the side collision fire rate for cars, light trucks, and vans is highest when a narrow object is struck. Would it therefore be reasonable to consider a pole side impact test as part of a subsequent upgrading of Standard No. 301?

11. Should the agency amend Standard No. 301 to prohibit fuel leakage in any crash test under Standard No. 208?