Appendix E
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: Transitioning
to Multiple Imputation - A New Method to Impute Missing Blood Alcohol
Concentration (BAC) values in FARS, DOT HS 809 403 (Washington, DC: January
2002).
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, 2000, DOT HS 809 337 (Washington,
DC: December 2001), 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). 645 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 2000, 592 agencies
reported to the NTD. Of that total, 67 transit agencies received exemptions
from detailed reporting because they operated 9 or fewer vehicles, and 7 were
deleted because their data were incomplete. Thus, 518 individual reporters were
included in the NTD, accounting for 90 to 95 percent of passenger-miles traveled
on transit. Of the transit agencies reporting, 23.7 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 2000, the number of agencies reporting to this database
was 592. Of that, 67 transit agencies received exemptions from detailed reporting
because they operated nine or fewer vehicles, and seven were deleted because
their data were incomplete. Thus, 518 individual reporters are included in the
full database in 2000. Of the transit agencies reporting, 23.7 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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