Q&A: Large trucks

January 2012

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 1.5 for passenger vehicles. Large trucks have a much lower rate per mile traveled of crashes resulting in nonfatal injuries or property damage only compared with passenger cars and light trucks.

3 Who dies in crashes involving large trucks?

In 2009, 3,163 people died in crashes involving large trucks. Fourteen percent of these deaths were truck occupants, 70 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, 98 percent of the deaths were the occupants in the passenger vehicles. Large trucks were involved in 9 percent of all motor vehicle crash deaths and 20 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,2 but a study in Indiana found that doubles did not show increased crash risk except on roads with snow, ice, or slush.3 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 U.S. 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 personnel conduct roadside inspections of trucks and drivers to enforce federal rules for equipment, hours of service, and vehicle maintenance and inspection. Federal and state personnel also conduct compliance reviews of carriers. Targeted toward those carriers considered as having the greatest potential for involvement in crashes, compliance reviews are on-site examinations of a motor carrier's operations to determine its safety fitness.

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.4,5,6,7,8

9 Is driver fatigue a factor in truck crashes?

Yes. Institute research has found that truck drivers behind the wheel for more than eight hours have a twofold increase in crash risk.9 Truckers' long work hours cause sleep deprivation, disruption of normal sleep/rest cycles, and fatigue.10,11 The Institute has found that truck drivers reporting hours-of-service violations are more likely to report having fallen asleep behind the wheel during the past month.12,13 Another study based on a national sample of large truck crashes found that a truck driver's hours-of-service violations and logbook violations resulting in the driver being placed out of service increased the likelihood that the truck driver would be determined to have precipitated the crash.14 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?

Truck drivers currently operate under regulations FMCSA issued in January 2004. Under the 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 of driving 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.

In December 2011, the agency issued a final rule largely in line with the current hours-of-service regulations. Drivers can continue to spend as many as 11 hours a day on the road, and they can't go over 60 work hours during a 7-day period or 70 work hours during an 8-day period. Restarts still are allowed, but drivers can only take 1 every 7 days, or 168 hours, compared with the 2 restarts under current rules. FMCSA added a requirement that a restart must include 2 overnight rest periods from 1 to 5 a.m. Commercial drivers and carriers must comply with the final rule by July 1, 2013.

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 2003.13

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.12,13,15 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.13 Some truck drivers refer to logbooks as "comic books" because they are so easily falsified.

13 Can hours-of-service monitoring be improved?

Yes. 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 U.S. 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.16 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 514,000 interstate motor carriers in 2010,17 and about 16,500 motor carrier safety compliance reviews of carriers were conducted in 2009.18 The rule also established technical performance standards for recorders rather than a single design standard. In late 2010, FMCSA proposed to expand the electronic onboard recorder requirement to all carriers that are required to use logbooks.

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.13

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 2009, 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.19 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.20 In 1999, almost 3 percent of drivers of large trucks in nonfatal crashes tested positive for illicit drugs.21

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 fatal crash will have a positive BAC by 14 percent.22

A 2008 report by the U.S. 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.23

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 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 2009, 52 percent of deaths among occupants of large trucks occurred in crashes in which their vehicles rolled over, compared with 56 percent of SUV occupant deaths and 47 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. 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 49 percent among passenger cars and SUVs and fatal multiple-vehicle crash risk by 20 percent.24 Based on an analysis of crashes occurring during 2004-08, the Institute estimates that vehicle stability control technology 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.25 The actual crash reductions from stability control systems on large trucks are not yet known.

17 Is defective equipment a factor in truck crashes?

Yes. 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.26 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-path crashes, brake violations significantly increased the likelihood that the truck was the striking vehicle.14

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.27

New large trucks must have automatic brake adjusters, visible brake adjustment indicators, and antilock brakes. Antilock brakes, which keep wheels from locking during hard braking, 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.28

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 Aug. 1, 2011, for three-axle tractors with a gross weight of 59,600 pounds or less. Two-axle tractors and tractors with a gross weight above 59,600 pounds must meet the reduced stopping distance requirements by Aug.1, 2013.

19 What crash avoidance systems are available for large trucks?

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. Based on crashes during 2004-08, 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. Stability control technology has 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 crash avoidance systems for large trucks are not yet known.25

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.29

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, trucks with rear wheels set very close to the back of the trailer, and various types of special purpose trucks. In 2010, the Institute studied how guards built to comply with the federal standards are performing in real-world crashes and found they still can allow severe passenger vehicle underride, often resulting in serious or fatal injury.30 The most common failures were due to weakness in the attachment between the guard and trailer, deformation of the trailer chassis itself, or excessive bending of one outboard end of the guard in narrow overlap crashes.

To further explore these issues, the Institute conducted a series of six crash tests using trailers and underride guards from three different manufacturers.31 The tests confirmed the findings of the 2010 study, showing that guards can fail and allow catastrophic underride at speeds as low as 35 mph. The tests also showed that some guards are much stronger than required by the regulation and are able to prevent underride in cases where those built to the minimum requirements cannot. Still, even the strongest guard was only able to prevent underride when it was struck near the center of the trailer.

As a result of its research, the Institute has petitioned the federal government to require stronger rear underride guards on large trucks. The standard should require testing closer to the ends of the guard, to ensure they are able to offer protection in offset crashes. Attachment hardware needs to be stronger than the guard itself so that the guard remains in place even after it starts to deform. Guards also need to be certified while attached to the trailer rather than a separate fixture, as currently allowed. Finally, NHTSA should determine whether guards can be closer to the ground and whether more trucks and trailer types can be subject to the rules.

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. Side underride guards, which are primarily intended to protect pedestrians and bicyclists, have been required in the EU since 1989.

Stronger underride guard requirements could prevent deaths and injuries 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 at night it's a different story. 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.32 A federal rule requires improved conspicuity — adding reflective sheeting or reflectors — for trailers manufactured after December 1993 and truck tractors manufactured after July 1, 1997. Effective December 2001, the U.S. 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 U.S. loads with a U.S. 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 U.S. 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 U.S. beyond the border zones but were not authorized to make deliveries between U.S. cities. The trucks had to satisfy all U.S. 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 being taken out of service. Less than 1 percent resulted in the driver being taken out of service. These were lower than the overall out-of-service rates for U.S. carriers inspected during the same time period.33 FMCSA terminated the demonstration project in 2009.

In April 2011, FMCSA proposed a pilot program allowing Mexican trucking companies to operate long-haul within the U.S.34 Mexico-domiciled carriers would proceed through three stages. During the first stage, the carriers' trucks would be inspected every time they enter the U.S. for at least 3 months. During the second stage these trucks would be inspected at a rate similar to that of other Mexican trucks entering the U.S. for short-haul trips. To proceed into the third stage, or permanent operating authority, a carrier must receive a satisfactory safety rating from its FMCSA compliance review, have no pending enforcement or safety improvement issues, and have spent at least 18 months in the first two stages of the program. Additionally, these carriers must operate electronic monitoring devices, installed by FMCSA, for the duration of the pilot program.

There's not enough information on the crash experience of Mexican trucks to determine if they have a higher crash risk than U.S. trucks.

References

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

²Stein, 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.

³Braver, 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.

⁴Campbell, K.L. 1991. Fatal accident involvement rates by driver age for large trucks. Accident Analysis and Prevention 23:287-95.

⁵Christie, R. and Fabre, J. 1999. Potential for fast-tracking heavy vehicle drivers. Melbourne, Australia: National Road Transport Commission.

⁶Blower, D.; Lyles, R.W.; Campbell, K.L.; and Stamatiadis, P. 1990. The Michigan heavy truck study. Lansing, MI: Michigan Office of Highway Safety Planning.

⁷Blower, D. 1996.The accident experience of younger truck drivers. Ann Arbor, MI: University of Michigan Transportation Research Institute.

⁸Frith, 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.

⁹Jones, 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.

¹⁰Insurance 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.

¹¹Insurance 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.

¹²Braver, 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.

¹³McCartt, 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.

¹⁴Blower, D.; Green, P.E.; and Matteson, A. 2011. Condition of trucks and truck crash involvement: evidence from the large truck crash causation study. Transportation Research Record 2194: 21-28.

¹⁵McCartt, 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.

¹⁶Insurance Institute for Highway Safety. 1995. Petition to the Federal Highway Administration to require electronic onboard recording devices for motor carriers, August 3. Arlington, VA.

¹⁷Federal Motor Carrier Safety Administration. 2010. Commercial Motor Vehicle Facts. Washington, DC. Accessed at http://www.fmcsa.dot.gov/documents/facts-research/CMV-Facts.pdf

¹⁸Federal Motor Carrier Safety Administration. 2010. A&I online- motor carrier analysis and information resources online: Summary of reviews by type. Washington, DC: U.S. Department of Transportation. Accessed at: http://ai.fmcsa.dot.gov/SafetyProgram/Review.aspx

¹⁹Federal Highway Administration. 1995. Random roadside drug and alcohol pilot program. Final report. Washington, DC: U.S. Department of Transportation.

²⁰Lund, 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.

²¹Federal Motor Carrier Safety Administration. 2000. Results from the 1999 drug and alcohol testing survey. Washington, DC: U.S. Department of Transportation.

²²Snowden, 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.

²³U.S. 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.

²⁴Farmer, C.M. 2010. Effects of electronic stability control on fatal crash risk. Arlington, VA: Insurance Institute for Highway Safety.

²⁵Jermakian, J. S. 2010. Crash avoidance potential of four large truck technologies. Arlington, VA: Insurance Institute for Highway Safety.

²⁶Jones, I.S. and Stein, H.S. 1989. Defective equipment and tractor-trailer crash involvement. Accident Analysis and Prevention 21:469-81.

²⁷Federal Highway Administration. 1997. National fleet safety survey, 1996. Report no. FHWA MC-98- 015. Washington, DC: U.S. Department of Transportation.

²⁸Allen, 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: U.S. Department of Transportation.

²⁹Braver, 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.

³⁰Brumbelow, M.L.; and Blanar, L. 2010. Evaluation of U.S. rear underride guard regulation for large trucks using real-world crashes. Report no. SAE 2010-22-0007. Proceedings of the 54th Stapp Car Crash Conference, 119-31. Warrendale, PA: Society of Automotive Engineers.

³¹Insurance Institute for Highway Safety. 2011. Status Report 46(2). Arlington, VA.

³²Morgan, C. 2001. Effectiveness of retroreflective tape on heavy trailers. Report no. DOT HS-809-222. Washington, DC: National Highway Traffic Safety Administration.

³³Federal Motor Carrier Safety Administration. 2009. Status report on NAFTA cross-border trucking demonstration project. Report no. MH-2009-034. Washington, DC: U.S. Department of Transportation.

³⁴Office of the Federal Register. 2011. Federal Register, vol. 76, no. 71, pp. 20807-20819. Federal Motor Carrier Safety Administration, Request for comments, Docket no. FMCSA-2011-0097; Pilot program on NAFTA long-haul trucking provisions. Washington, DC: National Archives and Records Administration.