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Appendix C
Data Source and Accuracy Statements
Chapter 2 Safety
AIR DATA
TABLE 2-1. Transportation Fatalities by Mode
TABLE 2-2. Injured Persons by Transportation Mode
TABLE 2-3. Transportation Accidents by Mode
TABLE 2-4. Distribution of Transportation Fatalities by Mode
TABLE 2-7. Transportation-Related Occupational Fatalities
TABLE 2-9. U.S. Air Carrier Safety Data
TABLE 2-10. U.S. Commuter Air Carrier Safety Data
TABLE 2-11. U.S. Air Carrier Fatal Accidents by First Phase of Operation
TABLE 2-12. U.S. Commuter Air Carrier Fatal Accidents by First Phase of Operation
TABLE 2-13. U.S. On-Demand Air Taxi Safety Data
TABLE 2-14. U.S. General Aviation Safety Data
National Transportation Safety Board investigators perform onsite and offsite
investigations of all accidents involving U.S. registered air carriers operating
under 14 CFR 121, 14 CFR 135, and general aviation U.S. Department of Transportation
(USDOT), Federal Aviation Administration (FAA) regulations. The investigators
compile information on fatalities and injuries for all accidents. The counts for
fatalities and serious injuries are expected to be extremely accurate. (See glossary
for serious injury definition.)
Exposure data (aircraft-miles, aircraft-hours, and aircraft-departures) are
obtained from the FAA, which in turn gets some of its exposure data from the USDOT,
Bureau of Transportation Statistics, Office of Airline Information (OAI) and other
exposure data from its own General Aviation and Air Taxi Activity and Avionics
(GAATAA) Survey. The OAI data represent 100 percent reporting by airlines. Tables
that include air carriers (14 CFR 121, scheduled and nonscheduled service) and
commuter air carriers (14 CFR 135, scheduled service only) use OAI exposure data.
Tables that include on-demand air taxi (14 CFR 135, nonscheduled service) and
general aviation use GAATAA Survey results. For information about the GAATA Survey,
please refer to the chapter 1 data accuracy statement for table 1-9.
The coefficients of variation for aircraft-hours vary by year, but are usually
in the 9 to 10 percent range for on-demand air taxi and are approximately 2 percent
for general aviation.
TABLE 2-15. Number of Pilot-Reported Near Midair Collisions by Degree of Hazard
Near Midair Collision reports are provided voluntarily by air carriers, general
aviation companies, and the military, and this information is added to the Near
Midair Collisions System database. Factors that may influence whether or not a
near midair collision is reported include the pilot’s or other crew member’s perception
of whether a reportable near midair collision occurred, which in turn can depend
on factors such as visibility conditions; the reporter’s flying experience; or
the size of the aircraft involved. A reportable incident is one in which an aircraft
is within 500 feet of another aircraft and a possibility of collision existed.
TABLE 2-16. Airline Passenger Screening Results by Type of Weapons Detected,
Persons Arrested, and Bomb Threats Received
Federal Aviation Regulations (FARs) mandate that passenger screening be performed
by each air carrier required to implement an approved security program. The USDOT,
Federal Aviation Administration, monitors the records of passenger screening in
accordance with FAR, and oversees compliance with the carriers’ security programs
through, for example, scheduled and unscheduled inspections. FAR requires the
reporting of information on bomb threats.
HIGHWAY DATA
TABLE 2-1.Transportation Fatalities by Mode
TABLE 2-2. Transportation Injuries by Mode
TABLE 2-3. Transportation Accidents by Mode
TABLE 2-4. Distribution of Transportation Fatalities by Mode
TABLE 2-5. Highway-Rail Grade-Crossing Safety Data and Property Damage
TABLE 2-7. Transportation-Related Occupational Fatalities
TABLE 2-17. Motor Vehicle Safety Data
TABLE 2-18. Motor Vehicle Fatalities, Vehicle-Miles, and Associated Rates
by Highway Functional System
TABLE 2-19. Occupant Fatalities by Vehicle Type and Nonoccupant Fatalities
TABLE 2-21. Passenger Car Occupant Safety Data
TABLE 2-22. Motorcycle Ride Safety Data
TABLE 2-23. Truck Occupant Safety Data
TABLE 2-24. Bus Occupant Safety Data
TABLE 2-25. Fatalities by Highest Blood Alcohol Concentration in Highway Crashes
TABLE 2-27. Motor Vehicle Fatal Crashes by Day of Week, Time of Day, and Weather
and Light Conditions
TABLE 2-28. Motor Vehicle Fatal Crashes by Posted Speed Limit
TABLE 2-20. Occupant and Nonmotorist Fatalities in Crashes by Number of Vehicles
and Alcohol Involvement
Fatalities
Highway fatality data come from the Fatality Analysis Reporting System (FARS),
which is compiled by trained FARS analysts at USDOT, National Highway Traffic
Safety Administration (NHTSA) regional offices. Data are gathered from a census
of police accident reports (PARs), state vehicle registration files, state drivers
licensing files, state highway department data, vital statistics, death certificates,
coroner/medical examiner reports, hospital medical reports, and emergency medical
service reports. A separate form is completed for each fatal crash. Blood alcohol
concentration (BAC) is estimated when not known. Statistical procedures used for
unknown data in FARS can be found in the NHTSA report A Method for Estimating
Posterior BAC Distributions for Persons Involved in Fatal Traffic Accidents, DOT
HS 807 094 (Washington, DC: July 1986).
Data are collected from relevant state agencies and electronically submitted
for inclusion in the FARs database on a continuous basis. Cross-verification of
PARs with death certificates ensures that undercounting is rare. Moreover, when
data are entered, they are checked automatically for acceptable range values and
consistency, enabling quick corrections when necessary. Several programs continually
monitor the data for completeness and accuracy. Periodically, sample cases are
analyzed for accuracy and consistency.
Note that the FARS data do not include motor vehicle fatalities on nonpublic
roads. However, previous NHTSA analysis found that these fatalities account for
2 percent or fewer of the total motor vehicle fatalities per year. (See glossary
for highway fatality definition.)
Injuries and Crashes
NHTSA’s General Estimates System (GES) data are a nationally representative
sample of police-reported crashes that contributed to an injury or fatality or
resulted in property damage, and involved at least one motor vehicle traveling
on a trafficway. Trained GES data collectors randomly sample PARs and forward
copies to a central contractor for coding into a standard GES system format. Documents
such as police diagrams or supporting text provided by the officers may be further
reviewed to complete a data entry.
NHTSA suggests that about half of motor vehicle crashes in the United States
are not reported to police and that the majority of these unreported crashes involve
minor property damage and no significant personal injury. A NHTSA study of injuries
from motor vehicle crashes estimated the total count of nonfatal injuries at over
5 million compared with the GES’s estimate of 3.2 million in 1998. (See glossary
for highway crash and injury definitions.)
(See U.S. Department of Transportation, National Highway Traffic Safety Administration,
Traffic Safety Facts, 1999, DOT HS 809 100 (Washington, DC: December 2000), appendices
B and C for further information on GES, including a table of standard errors applicable
to GES data.)
TABLE 2-29. Safety Belt and Motorcycle Helmet Use
The National Occupant Protection Use Survey (NOPUS), conducted biennially between
1994 and 2000 by the U.S. Department of Transportation, National Highway Traffic
Safety Administration is the source for these data.
In 1994 and 1996, NOPUS consisted of three separate studies: 1) the Moving
Traffic Study, which provides information on overall shoulder belt use, 2) the
Controlled Intersection Study, which provides more detailed information about
shoulder belt use by type of vehicle, characteristics of the belt users, and child
restraint use, and 3) the Shopping Center Study, which provides information on
rear-seat belt use and shoulder belt misuse. In 1998, the Shopping Center Study
was dropped from the survey. The Controlled Intersection Study includes the collection
of license plate information to link seat belt use to vehicle type. As the results
of the Controlled Intersection Study for 2000 were not available prior to publication,
only the Moving Traffic Study data were used in this table.
In 1998, NOPUS separated pickups from the light truck category, thereby creating
three categories of passenger vehicles: passenger cars, pickup trucks, and other
passenger vehicles. Other passenger vehicles include vans, minivans, and sport
utility vehicles. In this table, 1998 and 2000 data for pickup trucks and other
passenger vehicles are combined into the light truck category to allow comparison
to data from the earlier surveys.
In 1994, operators and riders wearing any type of helmet were counted as helmeted.
In 1996, 1998, and 2000, motorcycle helmets that meet USDOT standards are counted
as valid protection, whereas those that do not meet USDOT standards were treated
as if the operator/rider were not wearing a helmet.
Data collection from the Moving Traffic Study was conducted at 2,063 sites
across the country. Shoulder belt use was obtained for drivers and right-front
passengers only. Three observers (two observers in 1994 and 1996) were stationed
for 30 minutes at interstate/highway exit ramps, controlled (intersections with
stop signs or traffic signals), and uncontrolled intersections. Every day of the
week and all daylight hours (8 a.m. to 6 p.m.) were covered in each survey. Commercial
and emergency vehicles were excluded.
NOPUS was designed as a multistage probability sample to ensure that the results
would represent occupant protection use in the country. In the first stage, counties
were grouped by regions (northeast, midwest, south, west), level of urbanization
(metropolitan or not), and level of belt use (high, medium, or low). Fifty counties
or groups of counties were selected based on vehicle miles of travel in those
locations. In the next stage, roadways were selected from two categories: major
roads and local roads. Of the originally selected sites, some were found to be
ineligible during mapping and data collection, and at some sites no vehicles were
observed. In 2000, a total of 157,694 passenger vehicles were observed: 93,916
passenger cars and 63,778 light trucks (of which 24,747 were pickup trucks and
39,031 were other passenger vehicles). 1,444 motorcycles were also observed during
the 2000 NOPUS.
Each reported estimate has been statistically weighted according to the sample
design. Two kinds of error can be attributed to all survey research: sampling
and nonsampling. A measure, called the standard error, is used to indicate the
magnitude of sampling error. The source information provides two standard errors
along with each estimate. Nonsampling errors could include problems such as vehicles
not counted, incorrect determination of restraint use, and data entry mistakes,
among others.
TABLE 2-30. Estimated Number of Lives Saved by Use of Restraints
The U.S. Department of Transportation, National Highway Traffic Safety Administration
(NHTSA) uses data obtained from the Fatality Analysis Reporting System to calculate
the number of lives saved by the use of restraints. The methodology used is outlined
in a NHTSA report, Research Note, Estimating Lives Saved by Restraint Use in Potentially
Fatal Crashes (Washington, DC: June 1995). The general approach is to adjust the
observed number of fatalities by a determined effectiveness rate for each type
of restraint. This equates to subtracting the actual fatalities from the potential
fatalities to determine the number of lives saved. This method is more accurate
than earlier estimation methods since all calculations are derived from NHTSA’s
count of fatalities in which restraints were used. Reported restraint use is believed
to be accurate for fatalities.
The key to NHTSA’s calculations is the effectiveness estimate for preventing
fatalities for each type of restraint. With the exception of an adjustment in
the effectiveness estimate for front outboard air bag-only restraint use in passenger
cars (NHTSA, Fourth Report to Congress, Effectiveness of Occupant Protection Systems
and Their Use, Washington, DC, May 1999), a list of effectiveness estimates can
be found in a NHTSA report, Estimating Alcohol Involvement in Fatal Crashes in
Light of Increases in Restraint Use, published in March 1998.This report also
includes additional references describing the determination of these effectiveness
estimates.
TRANSIT DATA
TABLE 2-1. Transportation Fatalities by Mode
TABLE 2-2. Transportation Injuries by Mode
TABLE 2-3. Transportation Accidents by Mode
TABLE 2-4. Distribution of Transportation Fatalities by Mode
TABLE 2-31. Transit Safety and Property Damage Data
TABLE 2-32. Transit Safety Data by Mode for All Reported Accidents
TABLE 2-33. Transit Safety Data by Mode for All Reported Incidents
TABLE 2-34. Reports of Violent Crime, Property Crime, and Arrests by Transit
Mode
The data for this report are obtained from the U.S. Department of Transportation,
Federal Transit Administration's (FTA's) National Transit Database (NTD) Reporting
System. Transit agencies are required to file an NTD report at regular intervals
if they are recipients of Urbanized Area Formula Funds. In 1999, 587 agencies
reported to the NTD. Of that total, 64 transit agencies received exemptions from
detailed reporting because they operated 9 or fewer vehicles, and 7 were deleted
because their data were incomplete. Thus, 516 individual reporters were included
in the NTD, accounting for 90 to 95 percent of passenger-miles traveled on transit.
Of the transit agencies reporting, 56.5 percent contract for some or all of their
transportation from private or public companies or organizations.
Transit operators report fatalities, injuries, accidents, incidents, and property
damage in excess of $1,000. Electronic reporting has recently been implemented
for the NTD. Certification from a company’s Chief Executive Officer must accompany
all NTD reports along with an independent auditor’s statement. Upon receipt, an
NTD report is reviewed and outstanding items noted in writing to the agency that
submitted the form. (See glossary for transit fatality, injury, and accident definitions.)
Four major categories of transit safety are collected: 1) collisions, 2) derailments/buses
going off the road, 3) personal casualties, and 4) fires. These major categories
are divided into subcategories. The collisions category comprises collisions with
vehicles, objects, and people (except suicides). Of the four major categories,
only the first two are included in the definition of transit accidents adopted
in this report (see glossary). Understanding this definition of accident is relevant
to understanding how double counting is removed in the grand total of U.S. transportation
fatalities and injuries. (See cross modal comments in box
2-1.)
Transit data submitted to the NTD are generally considered accurate because
the FTA reviews and validates information submitted by individual transit agencies.
However, reliability may vary because some transit agencies cannot obtain accurate
information or misinterpret data.
Security
FTA collects security data from transit agencies serving urbanized areas of
over 200,000 in population, using Form 405, and manages it in the National Transit
Database (NTD). The reporting of security data follows the FBI Uniform Crime Reporting
Handbook (Washington, DC: 1984) and is divided into two categories: 1) Reported
Offenses, including violent and property crime, and 2) Arrests, consisting of
less serious crimes. The figures for violent and property crime are based on records
of calls for service, complaints, and/or investigations. They do not reflect the
findings of a court, coroner, jury, or decision of a prosecutor. Security data
were first reported in 1995 and were not compiled for earlier years.
In 1998, the number of agencies reporting to this database was 575.Of that,
60 transit agencies received exemptions from detailed reporting because they operated
nine or fewer vehicles, and six were deleted because their data were incomplete.
Thus, 509 individual reporters are included in the full database in 1998.Of the
transit agencies reporting, 56.2 percent contract for some or all of their transportation
from private or public companies or organizations.
RAILROAD DATA
TABLE 2-1. Transportation Fatalities by Mode
TABLE 2-2. Transportation Injuries by Mode
TABLE 2-3. Transportation Accidents by Mode
TABLE 2-4. Distribution of Transportation Fatalities by Mode
TABLE 2-5. Highway-Rail Grade-Crossing Safety Data and Property Damage
TABLE 2-7. Transportation-Related Occupational Fatalities
TABLE 2-35. Railroad and Grade-Crossing Fatalities by Victim Class
TABLE 2-36. Railroad and Grade-Crossing Injured Persons by Victim Class
TABLE 2-37. Train Fatalities, Injuries, and Accidents by Type of Accident
TABLE 2-38. Railroad Passenger Safety Data
TABLE 2-39. Railroad System Safety and Property Damage Data
TABLE 2-40. Fatalities and Injuries of On-Duty Railroad Employees
Railroads are required to file a report for each train accident resulting in
property damage in excess of $6,600, each highway-rail accident, and each incident
involving the operation of a railroad resulting in a fatality or a reportable
injury. (See glossary for reportable injury, train accident and incident, and
nontrain incident definitions.)
Reporting requirements, which are fixed in law, are very broad and encompass
events not strictly related to transportation. For example, if a passenger falls
on a staircase and breaks a leg in the station while going to a train, the injury
would be reported and appear in the data as a rail injury.
WATERBORNE TRANSPORTATION DATA
TABLE 2-1. Transportation Fatalities by Mode
TABLE 2-2. Transportation Injuries by Mode
TABLE 2-3. Transportation Accidents by Mode
TABLE 2-4. Distribution of Transportation Fatalities by Mode
TABLE 2-7. Transportation-Related Occupational Fatalities
TABLE 2-41. Waterborne Transportation Safety Data and Property Damage Related
to Vessel
Casualties
TABLE 2-42. Waterborne Transportation Safety Data Not Related to Vessel Casualties
U.S. waterborne fatality and injury data are based on reports required by CFR
Part 4.05-10. This code requires that the owner, agent, master, operator, or person
in charge file a written report of any marine casualty or accident within five
days of the accident. Reports must be delivered to Investigative Officers (IOs)
at a U.S. Coast Guard Marine Safety Office or Marine Inspection Office at the
U.S. Department of Transportation, who use these reports as guides to investigate
the marine casualty or accident. The IO ensures that all the entries on the forms
are filled out and errors are corrected. Regulations require IO notification of
marine casualties for certain circumstances, including loss of life; injuries
that require medical treatment beyond first aid; and, for individuals engaged
or employed onboard a vessel in commercial service, injuries that render a person
unfit to perform routine duties.
Incidents requiring an investigation include death, injury resulting in substantial
impairment, and other incidents determined important to promoting the safety of
life or property or to protect the marine environment. These incidents are investigated
in accordance with procedures set forth in the regulations. Furthermore, the Federal
Water Pollution Control Act mandates that certain incidents be reported to the
U.S. Coast Guard. The reports are entered into the Marine Safety Information System,
which is later analyzed and transferred to the Marine Safety Management System
maintained in Washington, DC.
RECREATIONAL BOATING DATA
TABLE 2-1. Transportation Fatalities by Mode
TABLE 2-2. Transportation Injuries by Mode
TABLE 2-3. Transportation Accidents by Mode
TABLE 2-4. Distribution of Transportation Fatalities by Mode
TABLE 2-43. Recreational Boating Safety, Alcohol Involvement, and Property
Damage Data
TABLE 2-44. Personal Watercraft Safety Data
TABLE 2-45. U.S. Coast Guard Search and Rescue Statistics, Fiscal Years
Operators of boats involved in an accident resulting in 1) a fatality, 2) an
injury requiring medical treatment beyond first aid, 3) damage to the vessel or
other property greater than $500 or complete loss of vessel, or 4) the disappearance
of a person from the vessel under circumstances indicating death or injury are
required to file a report with the U.S. Coast Guard. If a person dies within 24
hours of the occurrence, requires medical treatment beyond first aid, or disappears
from the vessel, reports must be made within 48 hours of the occurrence. In cases
involving only damage to the vessel and/or property, reports are to be submitted
within 10 days of the occurrence. Although there is no quantitative estimate of
the response rate, there may be considerable underreporting, especially of nonfatal
accidents, because of the difficulty of enforcing the requirement and because
boat operators may not always be aware of the law.
NATURAL GAS AND LIQUID PIPELINE DATA
TABLE 2-1. Transportation Fatalities by Mode
TABLE 2-2. Transportation Injuries by Mode
TABLE 2-3. Transportation Accidents by Mode
TABLE 2-4. Distribution of Transportation Fatalities by Mode
TABLE 2-46. Hazardous Liquid and Natural Gas Pipeline Safety and Property
Damage Data
U.S. fatality and injury data for natural gas pipelines are based on reports
filed with the U.S. Department of Transportation (USDOT), Office of Pipeline Safety
(OPS). Accidents must be reported as soon as possible, but no later than 30 days
after discovery. Reports are sent to the Information Systems Manager at the OPS.
Possible sources of error include a release going undetected; even if subsequently
detected and reported, it may not be possible to accurately reconstruct the accident.
Property damage figures are estimates. (See glossary for gas and liquid pipeline
fatality data and injury definitions.)
TABLE 2-6. Hazardous Materials Safety Data and Property Damage Data
Incidents resulting in certain unintentional releases of hazardous materials
must be reported under 49 CFR 171.16.Each carrier must submit a report to the
U.S. Department of Transportation, Research and Special Programs Administration
(RSPA) within 30 days of the incident, including information on the mode of transportation
involved, results of the incident, and a narrative description of the accident.
These reports are made available on the incident database within 60 days of receipt.
Fatalities and injuries are counted only if they are directly due to a hazardous
material. For example, a truck operator killed by impact forces during a motor
vehicle crash would not be counted as a hazardous-material fatality. RSPA verifies
all reported fatalities and injuries by telephone with the carrier submitting
the report.
Possible sources of error include a release going undetected; even if subsequently
detected and reported, it may not be possible to accurately reconstruct the accident.
Although RSPA acknowledges that there is some level of underreporting, it believes
that the underreporting is limited to small, nonserious incidents. As incident
severity increases, it is more likely that the incident will come to RSPA’s attention
and will ultimately be reported. Additionally, the reporting requirements were
extended to intrastate highway carriers on October 1, 1998, and the response rate
from this new group is expected to increase over time. Property damage figures
are estimates determined by the carrier prior to the 30-day reporting deadline
and are generally not subsequently updated. Property damage figures, therefore,
may underestimate actual damages.
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