Q&As: Large trucks

June 2010

1 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. The federal commercial vehicle maximum weight standard on the interstate highway system is 80,000 pounds gross vehicle weight, unless a higher maximum weight existed on the state level before July 1, 1956. Off the interstate highway system, states may set their own commercial vehicle weight standards. 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 that are even bigger than western doubles are allowed to travel on some roads. These trucks, called longer combination vehicles, either have three trailers or at least two, one of which is 29 feet or longer, or the tractor and two trailers have a combined weight exceeding 80,000 pounds. Longer combination vehicles are prohibited in many states and are allowed only in states that permitted them prior to June 1, 1991.

2 Do large trucks have high crash rates?

On average, drivers of large trucks travel many more miles than passenger vehicle drivers, and a high proportion of those miles are on interstates, which are the safest roads. In 2008, large trucks accounted for 4 percent of registered vehicles and 8 percent of miles traveled.1 Per unit of travel, large trucks are involved in more fatal crashes than passenger vehicles — 1.7 crashes per 100 million miles traveled in 2008 for large trucks, compared with compared with 1.4 for passenger vehicles. Large trucks have a much lower rate per mile traveled of crashes resulting in injuries or property damage only compared with passenger cars and light trucks.2

3 Who dies in crashes involving large trucks?

In 2008, about 4,000 people died in crashes involving large trucks. Fifteen percent of these deaths were truck occupants, 69 percent were passenger vehicle occupants, and 14 percent were pedestrians, bicyclists, or motorcyclists. In fatal two-vehicle crashes involving a passenger vehicle and a large truck, 97 percent of the deaths were the occupants in the passenger vehicles. Large trucks accounted for 4 percent of registered vehicles and 8 percent of vehicle miles traveled in 20081 but were involved in 11 percent of all motor vehicle crash deaths and 23 percent of passenger vehicle occupant deaths in multiple-vehicle crashes.

4 Are multiple-trailer trucks more likely to crash than single-trailer trucks?

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 is not firmly established. A study in Washington state found that doubles (tractors pulling two trailers) were two to three times as likely as other rigs to be in crashes,3 but a study in Indiana found that doubles did not show increased crash risk except on roads with snow, ice, or slush.4 One mitigating factor may be that doubles often are operated by drivers with good safety records working for large companies with active safety programs.

5 Who oversees large truck safety in the United States?

Two US Department of Transportation agencies plus individual 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 (vehicles operating across state lines). FMCSA regulations cover equipment, licensing, hours of service, and vehicle inspection and maintenance. States regulate intrastate trucks (trucks operating only within a single state's borders), and state inspectors are the primary enforcers of the federal rules for equipment, hours of service, and vehicle maintenance and inspection.

6 Do truck drivers need special licenses?

Yes. Licensing drivers is a state matter, but since 1992, federal law requires states to meet licensing standards for commercial driver's licenses (CDLs). Prior to 1992, a few states allowed any driver licensed to drive an automobile to drive a large truck or bus, and other states had weak testing and licensing standards for commercial drivers. Since 1992, federal law has established testing, licensing, and health standards for issuing CDLs. Both interstate and intrastate commercial drivers must obtain such licenses if they operate trucks with gross vehicle weight ratings of 26,001 pounds or more, if they transport 16 or more passengers, or if they transport hazardous materials. A national database of all CDL holders helps to deter truckers from using multiple state licenses to conceal their traffic convictions and also prevents disqualified drivers from being licensed.

7 Are there age restrictions on who is permitted to operate large trucks?

If large trucks cross state lines or carry hazardous materials, their drivers must be 21 or older. States can permit drivers ages 18-20 to operate large trucks only within the state.

8 Are young truck drivers at higher risk of crashing?

Yes. Studies conducted in Australia, New Zealand, and the United States indicate that truck drivers younger than 21 and in their 20s have a higher rate of involvement in both fatal and nonfatal crashes than older drivers.5,6,7,8,9

9 Is driver fatigue a factor in truck crashes?

Yes. Institute research found that truck drivers behind the wheel for more than 8 hours had a twofold increase in crash risk.10 Truckers' long work hours cause sleep deprivation, disruption of normal sleep/rest cycles, and fatigue.11,12 The Institute found that truck drivers reporting hours-of-service violations were more likely to report having fallen asleep behind the wheel during the past month.13,14 Based on a study of a national sample of large truck crashes, Blower and Green (2009) found that hours-of-service violations and logbook out-of-service violations increased the likelihood that a crash-involved truck would be determined to have precipitated the crash.15 The proportion of large truck crashes for which fatigue is a contributing factor is uncertain.

10 What are the current hours-of-service rules (work-hour limits) for truck drivers?

In January 2004, FMCSA implemented new hours-of-service regulations for truck drivers, increasing the required daily off-duty period but also increasing daily and weekly allowable driving times. Under the current rules, interstate commercial truck drivers are not allowed to drive more than 11 hours or drive after 14 hours since starting a duty shift until they take 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 allows truckers to get back behind the wheel after 34 hours off duty. Using this provision, a driver may log up to 77 hours in 7 days or 88 hours in 8 days.

Further modifications to the work rules took effect Oct. 1, 2005. These revisions provide that drivers who use sleeper berths in their trucks may split the required minimum 10-hour daily off-duty period into a period of at least 8 hours in the sleeper berth and a period of at least 2 hours in the sleeper berth or off duty. Short-haul truckers may extend their work day twice a week, and these drivers are exempt from a requirement to carry a logbook of their hours of work.

Federal courts overturned the rules in 2004 and again in 2007. In October 2009, FMCSA reached a court settlement with safety groups. Under the terms of the deal, FMCSA agreed to review and reconsider the rule and to publish a final rule by July 2011.

11 Have the new rules reduced fatigued driving?

No. Based on Institute surveys of long-distance truck drivers in two states (Pennsylvania and Oregon), drivers are spending more hours behind the wheel since the work rules changed in January 2004. They also report more instances of falling asleep at the wheel. In Pennsylvania, 19 percent of truck drivers admitted to dozing at the wheel at least once during the past month in 2005, up from 13 percent in 2003, under the old rule. The proportions in Oregon were 21 percent in 2005 compared with 12 percent in 2003.14

12 How are hours-of-service rules enforced? Is compliance a problem?

Current regulations allow truck drivers to record their hours in written logbooks that are reviewed by inspectors. Studies of long-distance truck drivers have found that work rules commonly are violated.13,14,16 About a third of drivers interviewed by the Institute in 2003, 2004, and 2005 admitted to often or sometimes omitting hours from their log books.14 Some truck drivers refer to logbooks as "comic books" because they are so easily falsified.

13 Can hours-of-service monitoring be improved?

Onboard computers reduce opportunities for violating the rules because they automatically record when a truck is driven. Beginning in the 1980s, Europe required mechanical (nonelectronic) tachographs, designed to record vehicle travel hours. Mechanical tachographs can be falsified more easily than onboard computers, so as of May 2006, 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 US Department of Transportation in 1995 to require the installation and use of tamper-resistant electronic onboard computers on commercial vehicles whose drivers are required to maintain written logbooks.17 The National Transportation Safety Board also has repeatedly recommended that such recorders be mandated. In 2000, FMCSA proposed to require these devices in all large trucks, but dropped the proposal from the work-hour rules that took effect January 2004. Under a final rule issued in April 2010, commercial truck and bus carriers must install electronic onboard recorders fleetwide if violations of hours-of-service rules are uncovered in 10 percent or more of fleet records during a single compliance review. The requirement goes into effect in June 2012. FMCSA estimates that 5,700 carriers would be affected during the first year of the rule. This represents a small fraction of all carriers. There were an estimated 715,000 interstate motor carriers in 2008,18 and about 16,500 motor carrier safety compliance reviews of carriers were conducted in 2009.19 The rule also established technical performance standards for recorders rather than a single design standard.

A large number of trucks already are equipped with onboard recorders. About 45 percent of the long-distance truck drivers interviewed by the Institute in 2005 said their trucks had electronic onboard recorders, up from about 18 percent in 2003 and 38 percent in 2004. Of the drivers who reported having recorders, only 10 percent or fewer said they used them in lieu of paper logbooks to show compliance with the work rules.14 A large proportion of trucks also are equipped with global positioning systems (GPS) which also indicate when trucks are in motion.

14 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. In 2008, 4 percent of fatally injured large truck drivers had blood alcohol concentrations (BACs) at or above 0.08 percent, compared with 35 percent of fatally injured passenger vehicle drivers. A 1995 roadside study in four states found that illicit drugs such as marijuana, cocaine, or amphetamines/methamphetamines were more prevalent than alcohol. Almost 5 percent of truck drivers tested positive for illicit drug use but only 0.2 percent tested positive for alcohol.20 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.21 In 1999, almost 3 percent of drivers of large trucks in nonfatal crashes tested positive for illicit drugs.22

Federal regulations require carriers to test all commercial drivers for drugs before employment, after crashes, and on a random basis. Alcohol tests are required after crashes and on a random basis. Alcohol test rules issued in 1994 place drivers out of service if they are found with any alcohol in their systems, and those who are found with BACs at or above 0.04 percent are disqualified from driving with a CDL. Random alcohol testing has been found to reduce the odds that a truck driver involved in a crash will have a positive BAC by 14 percent.23

A 2008 report by the US Government Accountability Office recommended that a national clearinghouse for positive drug and alcohol test results of commercial motor vehicle drivers be created. This would enable employers to be aware of previous positive test results when they screen applicant drivers.24

15 Are radar detectors legal in large trucks?

Since 1994, federal regulations have banned radar detector use in commercial vehicles involved in interstate commerce. The Institute and other organizations petitioned for this regulation in 1988 and again in 1990 because the only use for radar detectors is to evade speed limit enforcement.

16 Are large trucks prone to rolling over?

Yes. Their high centers of gravity increase the risk of rolling over, particularly on curved ramps. In 2008, 52 percent of deaths among occupants of large trucks occurred in crashes in which their vehicles rolled over, compared with 58 percent of SUV occupant deaths and 48 percent of pickup occupant deaths (both SUVs and pickups also have high centers of gravity). In contrast, 25 percent of car occupant deaths occurred in vehicles that rolled over.

Vehicle stability control systems may help to reduce this toll. These systems are designed to intervene when a truck's motion becomes unstable, possibly resulting in rollover, jackknife, or other loss of control. Roll stability control (RSC) intervenes when lateral acceleration on the truck and/or trailer puts the truck at risk of rollover. Electronic stability control (ESC) incorporates roll stability with directional stability to prevent understeer or oversteer conditions that could result in loss-of-control crashes. Neither RSC nor ESC is currently required for large trucks in the United States. In Institute studies, ESC has been found to reduce fatal single-vehicle crash risk by 51 percent among passenger cars and SUVs and fatal multiple-vehicle crash risk by 19 percent.25 The Institute estimates that vehicle stability control has the potential to prevent or mitigate as many as 31,000 crashes involving large trucks each year, including up to 20 percent of moderate-to-serious injury large truck crashes and 11 percent of fatal large truck crashes.26 The actual crash reductions from stability control systems on large trucks are not yet known.

17 Is defective equipment a factor in truck crashes?

In the late 1980s, Institute researchers examined crashes of large trucks in the state of Washington and found that tractor-trailers with defective equipment were twice as likely to be in crashes as trucks without defects.27 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.

A recent study examined the role of defective equipment in crashes included in the Large Truck Crash Causation Study. The study gathered detailed information on a national sample of 2001-2003 crashes involving an evident injury and at least one large truck. According to Blower and Green (2009), post-crash inspections of the trucks indicated that almost 55 percent had at least one mechanical violation, and almost 30 percent had at least one out-of-service condition. Of all equipment violations, violations in the brake (36 percent) and lighting (19 percent) systems were the most frequent. A truck with an out-of-service brake condition was 1.8 times more likely to be the vehicle that precipitated the crash. In rear-end and crossing-paths crashes, brake violations significantly increased the likelihood that the truck was the striking vehicle.15

18 Are braking systems on large trucks as effective as passenger vehicle brakes?

Compared with passenger vehicles, stopping distances for trucks are much longer. On wet and slippery roads, there are even greater disparities between the braking capabilities of large trucks and cars.

Braking disparities can be aggravated by poor maintenance of truck braking systems. In a 1996 survey involving inspections of a representative sample of large trucks on the road, out-of-adjustment brakes were the most common reason for authorities to order trucks out of service.28

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 tractor-trailer jackknife. Antilocks have been required on new tractors as of March 1997 and on new trailers, single-unit trucks, and buses as of March 1998. A recent study found that antilocks did not increase maintenance and repair expenses to the brake system.29

In July 2009, NHTSA issued a final rule decreasing the maximum stopping distances for air-braked trucks by 30 percent. The rule will go into effect on August 1, 2011 for three-axle tractors with a GVWR of 59,600 pounds or less. Two-axle tractors and tractors with a GVWR above 59,600 pounds must meet the reduced stopping distance requirements by August 1, 2013.

19 Are crash avoidance systems available for large trucks?

Yes. Several crash avoidance technologies have been developed for large trucks. To date, penetration of these technologies into the large truck fleet has been slow, but the technologies have the potential to substantially reduce large truck crashes. The Institute examined the maximum potential crash reductions associated with each of four technologies: side view assist, forward collision warning/mitigation, lane departure warning/prevention, and vehicle stability control. A combination of all four technologies could prevent or mitigate as many as 107,000 police-reported crashes each year, representing 28 percent of all crashes involving large trucks. The technology could prevent or mitigate as many as 12,000 nonfatal injury large truck crashes and 835 fatal large truck crashes each year. Vehicle stability control the greatest potential for preventing or mitigating large truck crashes involving nonfatal or fatal injuries, while side view assist has the greatest potential for preventing large truck crashes of any severity. The actual crash reductions from stability control systems for large trucks are not yet known.26

20 What are truck underride crashes?

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 passenger vehicles estimated that underride occurred in half of these crashes. Of the underride crashes, 57 percent involved the front of the truck, 22 percent involved the rear, and 20 percent the side.30

A federal rule to upgrade the rear-impact guard standard for new trailers took effect in January 1998. Several truck types are exempt from the rule, including straight trucks, and wheels-back trucks, and various types of special purpose trucks. The effects of the improved guard in preventing deaths and injuries in rear impact crashes are unknown. Regulations in Canada require stronger rear underride guards than in the United States.

There is no requirement for front or side underride guards in the United States. European Union regulations have required front underride guards on large trucks since 2003. Underride guards have been required on the sides of trucks since 1989. These guards are primarily intended to protect pedestrians and bicyclists. The regulations in Canada impose more stringent requirements for rear underride guards than US regulations.

Underride guards prevent many deaths and injuries that occur in rear-impact crashes

 

21 Can trucks be made more visible to other drivers at night?

During the day trucks are easy to see, but it is different at night. Research indicates that when drivers of other vehicles can recognize medium and heavy trucks more easily, they 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.31 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. Effective December 2001, the US Department of Transportation requires the enhanced markings on all trailers on the road, not just new ones.

Reflective markings improve conspicuity of trucks at night

 

22 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 US loads with a US destination.

With the signing of the North American Free Trade Agreement (NAFTA) in 1992, Mexico and the United States agreed to permit cross-border trucking within both countries by the end of 1995. However, most Mexican trucks still are restricted to border cities because of concerns about Mexican motor carriers' ability to meet US safety and insurance requirements. Currently, only a few approved carriers can drive beyond the border cities.

A demonstration project beginning in 2007 allowed 27 Mexican trucking companies to operate long-haul within the United States. The trucks from these carriers could transport freight between Mexico and the US beyond the border zones but were not authorized to make deliveries between US cities. The trucks had to satisfy all US safety requirements and were inspected every time they crossed the border and traveled beyond the border cities. Eight percent of inspections of these trucks during September 2007-September 2008 resulted in a vehicle out-of-service violation. The driver out-of-service rate was less than one percent. This was lower than the overall out-of-service rates for US carriers inspected during the same time period.32 FMCSA terminated the demonstration project in 2009.

Data on the crash experience of Mexican trucks are insufficient to determine if they have a higher crash risk than US trucks.

References

¹Federal Highway Administration. 2010. Highway statistics, 2008. Washington, DC: US Department of Transportation.

²National Highway Traffic Safety Administration. 2009. Traffic safety facts 2008: large trucks. Report no. DOT HS-811-158. Washington, DC: US Department of Transportation.

³Stein, H.S. and Jones, I.S. 1988. Crash involvement of large trucks by configuration: a case-control study. American Journal of Public Health 78:491-98.

⁴Braver, E.R.; Zador, P.L.; Thum, D.; Mitter, E.L.; Baum, H.M.; and Vilardo, F.J. 1997. Tractor-trailer crashes in Indiana: a case study of the role of truck configuration. Accident Analysis and Prevention 29:79-96.

⁵Campbell, K.L. 1991. Fatal accident involvement rates by driver age for large trucks. Accident Analysis and Prevention 23:287-95.

⁶Christie, R. and Fabre, J. 1999. Potential for fast-tracking heavy vehicle drivers. Melbourne, Australia: National Road Transport Commission.

⁷Blower, D.; Lyles, R.W.; Campbell, K.L.; and Stamatiadis, P. 1990. The Michigan heavy truck study. Lansing, MI: Michigan Office of Highway Safety Planning.

⁸Blower, D. 1996.The accident experience of younger truck drivers. Ann Arbor, MI: University of Michigan Transportation Research Institute.

⁹Frith, W.J. 1994. A case-control study of heavy vehicle drivers' working time and safety. Proceedings of the 17th Australian Road Research Board Conference, 17-30. Queensland, Australia: Australian Road Research Board.

¹⁰Jones, I.S. and Stein, H.S. 1987. Effect of driver hours of service on tractor-trailer crash involvement. Arlington, VA: Insurance Institute for Highway Safety.

¹¹Insurance Institute for Highway Safety. 2000. Comment to the Federal Motor Carrier Safety Administration concerning proposed changes to commercial truck drivers hours-of-service rules. Docket no. FMCSA-1997-2350, August 4. Arlington, VA.

¹²Insurance Institute For Highway Safety. 2008. Comment to the Federal Motor Carrier Safety Administration concerning the interim final rule on hours of service for commercial truck drivers. Docket no. FMCSA-2004-19608. March 6, 2008. Arlington, VA.

¹³Braver, E.R.; Preusser, C.W.; Preusser, D.F.; Baum, H.M.; Beilock, R.; and Ulmer, R. 1992. Long hours and fatigue: a survey of tractor-trailer drivers. Journal of Public Health Policy 13:341-66.

¹⁴McCartt, A.T.; Hellinga, L.A.; and Solomon, M.G. 2008. Work schedules of long-distance truck drivers before and after 2004 hours-of-service rule change. Traffic Injury Prevention 9:201-10.

¹⁵Blower, D. and Green, Paul E. 2009. Truck mechanical condition and crashes in the Large Truck Crash Causation Study. Report no. UMTRi-2009-09. Ann Arbor, MI: University of Michigan Transportation Research Institute.

¹⁶McCartt, A.T.; Hammer, M.C.; and Fuller, S.Z. 1997. Work and sleep/rest factors associated with driving while drowsy: experiences among long-distance truck drivers. Proceedings of the 41st Annual Conference of the Association for the Advancement of Automotive Medicine, 95-108. Des Plaines, IL: Association for the Advancement of Automotive Medicine.

¹⁷Insurance Institute for Highway Safety. 1995. Petition to the Federal Highway Administration to require electronic onboard recording devices for motor carriers, August 3. Arlington, VA.

¹⁸Bureau of Transportation Statistics. 2010. National transportation statistics: Table 1-2: Number of air carriers, railroads, interstate motor carriers, marine vessel operators, and pipeline operators. Washington, DC: Research and Innovative Technology Administration. Accessed at http://www.bts.gov/publications/national_transportation_statistics/html/table_01_02.html

¹⁹Federal Motor Carrier Safety Administration. 2010. A&I online- motor carrier analysis and information resources online: Summary of reviews by type. Washington, DC: US Department of Transportation. Accessed at: http://ai.fmcsa.dot.gov/SafetyProgram/Review.aspx

²⁰Federal Highway Administration. 1995. Random roadside drug and alcohol pilot program. Final report. Washington, DC: US Department of Transportation.

²¹Lund, A.K.; Preusser, D.F.; Blomberg R.D.; and Williams, A.F. 1988. Drug use by tractor-trailer drivers. Journal of Forensic Sciences 33:648-61.

²²Federal Motor Carrier Safety Administration. 2000. Results from the 1999 drug and alcohol testing survey. Washington, DC: US Department of Transportation.

²³Snowden, C.B.; Miller, T.R.; Waehrer, G.M.; and Spicer, R.S. 2007. Random alcohol testing reduced alcohol-involved fatal crashes of drivers of large trucks. Journal of Studies on Alcohol 68:634-40.

²⁴US Government Accountability Office. 2008. Motor carrier safety; Improvements to drug testing programs could better identify illegal drug users and keep them off the road. Report no. GAO-08-600. Washington, DC.

²⁵Farmer, C.M. 2010. Effects of electronic stability control on fatal crash risk. Arlington, VA: Insurance Institute for Highway Safety.

²⁶Jermakian, J. S. 2010. Crash avoidance potential of four large truck technologies. Arlington, VA: Insurance Institute for Highway Safety.

²⁷Jones, I.S. and Stein, H.S. 1989. Defective equipment and tractor-trailer crash involvement. Accident Analysis and Prevention 21:469-81.

²⁸Federal Highway Administration. 1997. National fleet safety survey, 1996. Report no. FHWA MC-98- 015. Washington, DC: US Department of Transportation.

²⁹Allen, K. 2009. An in-service analysis of maintenance and repair expenses for the anti-lock brake system and underride guard for tractors and trailers. Report no. DOT HS-811-109. Washington, DC: US Department of Transportation.

³⁰Braver, E.R.; Cammisa, M.X.; Lund, A.K.; Early, N.; Mitter, E.L; and Powell, M.R. 1997. Incidence of large truck-passenger vehicle underride crashes in the Fatal Accident Reporting System and the National Accident Sampling System. Transportation Research Record 1595:27-33.

³¹Morgan, C. 2001. Effectiveness of retroreflective tape on heavy trailers. Report no. DOT HS-809-222. Washington, DC: National Highway Traffic Safety Administration.

³²Federal Motor Carrier Safety Administration. 2009. Status report on NAFTA cross-border trucking demonstration project. Report no. MH-2009-034. Washington, DC: US Department of Transportation.