What is a large truck?
Large trucks weigh more than 10,000 pounds
and can be either single-unit vehicles or
combination vehicles consisting of a single-unit
truck or tractor pulling one or more trailers.
In most states, the maximum permitted length
for a single trailer is 53 feet. Tractors
pulling two 28-foot trailers are known as
twins or western doubles. Trucks even bigger
than western doubles are allowed to travel
on some of the nation's roads. These trucks,
called longer combination vehicles, either
have three trailers or have at least two trailers,
one of which is 29 feet or longer, or the
tractor and two trailers have a combined weight
exceeding 80,000 pounds.
2. Do large trucks
have high crash rates?
Large trucks are involved in more fatal crashes
per unit of travel than passenger vehicles
-- compared with 1.8 crashes per 100 million
miles traveled in 2002. The disparities between
large trucks and passenger vehicles vary by
specific vehicle type, with passenger cars
having the lowest fatal involvement rate and
tractor-trailers having the highest rate.
The higher fatal involvement rate for large
trucks occurs although a much higher proportion
of their miles is traveled on interstate highways,
which are the safest roads. Their higher fatal
involvement rate is attributable to the size
disparity between large trucks and passenger
vehicles. Tractor-trailers have a lower rate
of nonfatal crashes resulting in injuries
or property damage only, compared with passenger
3. Who dies in crashes
involving large trucks?
About 5,000 people die each year in crashes
involving large trucks and about 85 percent
of them aren't truck occupants. In fatal two-vehicle
crashes involving passenger vehicles and large
trucks, 98 percent of the deaths occur to
the people in the passenger vehicles. Large
trucks accounted for 3 percent of registered
vehicles and 8 percent of vehicle miles traveled
in 2002 but were involved in 11 percent of
all passenger vehicle occupant deaths and
in 21 percent of multiple-vehicle passenger
vehicle occupant deaths.
4. Are multiple-trailer
trucks more likely to crash than single-trailer
Multiple-trailer trucks have more handling
problems than single-trailer trucks. In general,
the additional connection points contribute
to greater instability, which can lead to
jackknifing, overturning, and lane encroachments.
But the relationship between multiple-trailer
trucks and crash risk isn't firmly established.
A study in Washington state found doubles
(tractors pulling two trailers) were two to
three times as likely as other rigs to be
in crashes, but a study in Indiana found doubles
didn't show increased crash risk except on
roads with snow, ice, or slush. Doubles often
are operated by drivers with good safety records
working for large companies with active safety
5. Who oversees
large truck safety in the United States?
Two agencies of the U.S. Department of Transportation
and the states oversee large truck safety.
The National Highway Traffic Safety Administration
(NHTSA) sets standards for new truck equipment
and has some jurisdiction over equipment standards
for trucks currently on the road. The Federal
Motor Carrier Safety Administration (FMCSA)
oversees the safety of commercial vehicles
in interstate commerce, and this agency's
regulations cover equipment, licensing, hours
of service, and vehicle inspections and maintenance.
The rules pertaining to licensure, vehicle
maintenance and hours of service are primarily
enforced by the states. States regulate intrastate
6. Do truck drivers
need special licenses?
Commercial drivers' licenses have been required
since 1992 for commercial vehicle operations.
Each driver holding a commercial drivers license
is entered into a national database. This
requirement is intended to ensure that truckers
do not use multiple state licenses to conceal
the overall total of their traffic violations.
Both interstate and intrastate commercial
drivers must obtain such licenses if they
operate trucks with gross vehicle weight ratings
of 26,001 or more pounds, if they transport
16 or more passengers, or if they transport
7. Are there age
restrictions on who is permitted to operate
If large trucks cross state lines or if they
carry hazardous materials, their drivers must
be at least age 21. States permit drivers
ages 18-20 to operate large trucks only within
8. Are young truck
drivers at higher risk of crashing?
Yes. Studies conducted in the United States,
New Zealand, and Australia indicate that truck
drivers younger than 21 and in their 20s have
a high rate of involvement in both fatal and
9. Is driver fatigue
a factor in truck crashes?
Yes. Driver fatigue is associated with truck
crashes. Research shows truck crash risk increases
with driver hours behind the wheel. Crash
risk is also higher between midnight and 6
a.m. The long hours truck drivers work cause
sleep deprivation, circadian desynchronization,
and fatigue. The Institute has found that
truck drivers reporting hours-of-service violations
were more likely to report having fallen asleep
behind the wheel during the month before the
interview. The proportion of large truck crashes
for which fatigue is a contributing factor
10. What are the
hours-of-service rules (work hour limits)
and who violates them?
Under federal hours-of-service regulations
that took effect January 2004, interstate
commercial truck drivers won't be allowed
to drive more than 11 hours or drive after
14 hours on duty until they have had a 10-hour
break. Drivers cannot drive after accruing
60 work hours during a 7-day period or 70
work hours during an 8-day period, but a "restart"
provision will allow truckers to drive 77
hours in 7 days or 88 hours in 8 days. Studies
suggest that work rules are commonly violated.
11. How can violations
of the hours-of-service rules be reduced?
Current regulations allow drivers to use written
logbooks of their hours, which truck drivers
call "comic books" because they are so easily
falsified. Onboard computers reduce the opportunities
for violating the rules because they automatically
record when a truck is driven and its speed.
Europe has required mechanical tachographs,
which are nonelectronic devices designed to
record vehicle travel hours, for about 30
years. Mechanical tachographs can be more
easily falsified than onboard computers, so
by August 2004, new trucks and intercity buses
registered in the European Union must be equipped
with electronic recording devices. The Institute
and five other organizations petitioned the
Department of Transportation to require the
installation and use of tamper-resistant electronic
onboard computers on commercial vehicles whose
drivers now are required to maintain written
logbooks. The National Transportation Safety
Board also has repeatedly recommended that
such recorders be mandated. In 2000, FMCSA
published a proposal to require these devices
but dropped the proposal from the final work-hour
rules that take effect January 2004.
12. Is the use
of alcohol and other drugs among truckers
a big problem?
Alcohol is much less of a problem among truck
drivers than among passenger vehicle drivers.
Only 6 percent of all tractor-trailer drivers
who were killed in crashes during 2002 had
blood alcohol concentrations of 0.08 percent
or more, compared with 32 percent of fatally
injured passenger vehicle drivers. A 1995
roadside study in four states found that almost
5 percent of truck drivers tested positive
for illicit drug use but only 0.2 percent
tested positive for alcohol. This study did
not test for use of legal over-the-counter
stimulants, which were present in 12 percent
of truck drivers in an earlier Institute study.
In 1999 almost 3 percent of drivers of large
trucks tested positive for illicit drugs after
a non-fatal crash. Federal regulations require
carriers to test all commercial drivers for
drugs before employment, after crashes, and
on a random basis. Alcohol tests are required
only after crashes and on a random basis.
New alcohol test rules were issued in 1994
that place drivers out of service if they
are found with any alcohol in their systems.
13. Are radar detectors
legal in large trucks?
Radar detector use is banned in commercial
vehicles involved in interstate commerce.
The Institute and other organizations petitioned
for such a regulation in 1988 and again in
1990 because the only use for radar detectors
is to evade speed limit enforcement. FHWA
issued the ban on detectors, effective in
1994, but did not specify a mechanism for
14. Are large trucks
prone to rolling over?
Yes. The high center of gravity of large trucks
increases their risk of rolling over, particularly
on curving ramps. A little more than half
of deaths among occupants of large trucks
occur in crashes in which their vehicle rolled
over, compared with about 60 percent of SUV
occupant deaths and 45 percent of pickup occupant
deaths (both SUVs and pickups also have high
centers of gravity). In contrast, about 25
percent of passenger car occupant deaths occurred
in vehicles that rolled over.
15. Is defective
equipment a factor in truck crashes?
Yes. Institute researchers who examined crashes
of large trucks in Washington state found
that tractor-trailers with defective equipment
were twice as likely to be in crashes as trucks
without defects. Brake defects were most common.
They were found in 56 percent of the tractor-trailers
involved in crashes. Steering equipment defects
were found in 21 percent of crash-involved
trucks. The proportion of large truck crashes
in which defective equipment is a contributing
factor is uncertain. Underride guards prevent
many of the deaths and injuries that occur
in rear impact crashes.
16. How effective
are truck brakes?
Compared with passenger vehicles, stopping
distances for trucks are much longer. On wet
and slippery roads there are greater disparities
between the braking capabilities of large
trucks and cars. Brake problems will be aggravated
by poor maintenance practices. Out-of-adjustment
brakes are the most common reason for authorities
to order trucks out of service. New large
trucks must have automatic brake adjusters,
visible brake adjustment indicators, and antilock
brakes. Antilock brakes, which keep wheels
from locking, improve driver control of trucks
during emergency stops and reduce the likelihood
of jackknife in tractor-trailers.
17. When were large
trucks required to have antilock brakes?
NHTSA issued a rule in 1995 requiring antilock
brakes on newly manufactured medium and heavy
vehicles. They were on new tractors as of
March 1997 and on new trailers, single-unit
trucks, and buses as of March 1998. Antilocks
are required on all new trucks, buses, and
trailers in Japan and the European Union.
18. What are truck
In an underride crash, a passenger vehicle
goes partially or wholly under a truck or
trailer, increasing the likelihood of death
or serious injury to the passenger vehicle
occupants. A 1997 Institute study of fatal
crashes between large trucks and cars estimated
that front, rear, or side underride occurred
in half of these crashes. A federal rule to
upgrade the rear impact guard standard for
new trailers only took effect in January 1998.
The new guard will prevent many of the deaths
and injuries that occur in rear impact crashes.
19. Can trucks be
made more visible to other drivers at night?
During the day, trucks are easy to see, but
it's a different story at night. Research
indicates that if drivers of other vehicles
can recognize medium and heavy trucks more
easily, these drivers can gauge the trucks'
speed and distance more accurately and react
sooner when necessary. Federal studies have
reported that enhancing the conspicuity of
trailers reduced the incidence of crashes
in which trailers were hit from the side or
rear at night on unlighted roads. A federal
rule requires improved conspicuity -- adding
reflective sheeting or reflectors -- for trailers
manufactured after December 1993 and truck
tractors (bobtails) manufactured after July
1, 1997. Starting June 1, 2001, the Department
of Transportation required the enhanced markings
for all trailers on the road, not just new
20. Are Mexican
and Canadian trucks allowed to operate in
the United States?
Canadian trucks are allowed to deliver loads
from Canada and pick up loads with a Canadian
destination, but generally cannot pick up
U.S. loads with a U.S. destination. At this
time, Mexican trucks are restricted to border
cities, but the U.S. government has announced
its intentions to permit Mexican motor carriers
the same access to the United States as Canadian
motor carriers, provided they meet certain
safety and insurance requirements. Because
of legal challenges, these plans currently
are on hold. At least initially, few Mexican
motor carriers have applied for such operating
21. Do Mexican trucks
pose a safety risk on U.S. highways?
Data on the crash experience of Mexican trucks
are insufficient to determine if they have
a higher crash risk than U.S. trucks. Past
safety inspection data indicate that out-of-service
rates for Mexican trucks were lower within
California, a state with a stringent inspection
program, than in the three other border states
with less frequent inspections. However, within
the past few years, more safety inspectors
have been hired and border inspection facilities
have been improved. Information from IIHS.
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