This work was unducted in the early 1990s and funded by the University Transportation Centers program from the United States Department of Transportation. The Federal Motor Carrier Safety Administration (then the FHWA - Office of Motor Carriers) made available to us their entire database for both Safety Review and Compliance Review (SR/CR) audits and roadside inspections. The database contained information on the characteristics and safety performances of 75,000 U.S. motor carrier firms, and was considerably larger than any other that has been used in previous formal analyses of motor carrier crashes.

1. Leon N. Moses and Ian Savage (1994). The effect of firm characteristics on truck accidents. Accident Analysis and Prevention 26(2):173-179.
[Journal Website]  [Manuscript Version]

The first phase of our work included an investigation of the relationship between trucking firm characteristics - such as size, ownership and cargo carried - and crashes. We also investigated the ability of the SR/CR program to identify the trucking firms with the poorest safety records. Our work led to the following conclusions:

• Motor carrier crash rates decline as firm size rises. The largest firms have crash rates about half those of the smallest firms.

• Private carriers, have crash rates 20% lower than for-hire carriers. Presumably, these firms have a strong incentive for safe operation because it is the company's own cargo that would be damaged in a crash.

• Among the for-hire carriers, the General Commodity class of carriers have crash rates about 10% higher than those firms who specialize in specific cargoes. Presumably specialist firms thrive by building up a good reputation with a relatively small number of shippers and those shippers become well acquainted with the transport business characteristics of the trucking firms they use.

• Carriers of hazardous materials have a rate of crashes involving fatalities and serious injuries some 20% higher than that of other trucking firms. Firms that carry hazardous materials as part of a general freight business are worse than firms who specialize in particular hazardous commodities. Further analysis revealed that the transportation of packaged gases and liquids in tank-trailers is the most hazardous. Suggested explanations are poor packaging standards for gases, and the instability of partially filled tank- trailers.

• Certain management safety practices are effective in reducing crashes. The firms with the best safety records are those firms who keep records of crashes and investigate crashes to determine if disciplinary or educational action is necessary for the drivers involved. Firms who are conscientious in enforcing the maximum hours-of-service rules for drivers were found to have superior safety records. These sections of the audit, namely parts 394 and 395, are the best leading indicator of a firm's safety performance.

This analysis is an extension of a previously published paper: Leon N. Moses and Ian Savage (1992). The effectiveness of motor carrier safety audits. Accident Analysis and Prevention 24(5):479-496.
[Journal Website]  [Paper]

2. Leon N. Moses and Ian Savage (1996). Identifying dangerous trucking firms. Risk Analysis 16(3):359-366.
[Journal Website]  [Manuscript Version]

The paper develops a statistical procedure for predicting the safety performance of motor carriers based on characteristics of firms and results of two government safety enforcement programs. One program is an audit of management safety practices, and the other is a program to inspect drivers and vehicles at the roadside for compliance with safety regulations. The technique can be used to provide safety regulators with an empirical approach to identify the most dangerous firms and provide a priority list of firms against which educational and enforcement actions should be initiated. The government needs to use such an approach rather than directly observing crash rates because the most dangerous firms are generally small and, despite relatively high crash rates, crashes remain rare events.

The technique uses negative-binomial regression procedures on a dataset of 20,000 firms. The definition of poor performance in roadside inspection is based on both the rate of inspections per fleet mile and the average number of violations found during an inspection. This choice was made because selection for inspection has both a random and nonrandom component.

The results of the study suggest that both of the government's safety programs help identify the most dangerous firms. The 2.5% of firms that do poorly in both programs have an average crash rate twice that of the mean for all other firms.

3. Leon N. Moses and Ian Savage (1997). A cost-benefit analysis of United States motor carrier safety programs. Journal of Transport Economics and Policy 31(1):51-67.
[Journal Website]  [JSTOR]  [Extended Working Paper]

The second phase of our work evaluated the economic and social costs and benefits of the safety programs. The SR/CR audit program annually recommends approximately two thousand motor carrier firms for enforcement and education actions. As a result of these remedial actions, targeted firms lower their crash rates by 43%. The benefits of reduced crashes from this program exceed both government and carrier firm costs by a ratio of over 4:1.

The same is not true for the roadside inspection program. Here the benefits exceed the costs under only the most favorable assumptions regarding the number of crashes avoided. Costs clearly exceed benefits when more realistic assumptions are introduced. Most of the costs of this program are borne by motor carriers whose trucks are delayed by inspections rather than government.

Included in the costs and benefits of the two safety programs are estimates of a "deterrence effect" which assumes that firms improve their safety performance even though they have not been audited or had their vehicle(s) placed out of service. The deterrence effect has a credible maximum value of 50% of the direct effects of the programs, with a more plausible value of 25% of the direct effects.

The net social benefits from the safety programs would be even greater if resources were diverted from the roadside inspection program to the audit program. Unfortunately, the FHWA is currently adopting the reverse policy. In addition, the roadside program could be considerably more efficient if the government conducted shorter inspections, at less predictable locations that greater focus to the condition of the driver. However, this policy is only recommended if the penalties for exceeding permitted hours, the primary violation found in inspections, are made a good deal more severe.

4. Ian Savage (1999). Safety Regulation. Global Truck and Commercial Vehicle Technology. London: World Markets Research Centre's Business Briefing Series, 86-90.
[Manuscript Version]

This shorter paper for an industry trade publication summarizes our earlier work and puts it in the wider context of truck safety. It also updates events to 1999.

5. Leon N. and Ian Savage (1993). Characteristics of motor carriers of hazardous materials. In Frank F. Saccomanno and Keith Cassidy (eds.) Transportation of Dangerous Goods: Assessing the Risks. Waterloo, Ontario: University of Waterloo, Institute for Risk Research.
[1992 Conference Version]

This paper investigates whether trucking firms that haul hazardous materials differ from firms who do not haul these goods. It employs a database of 75,000 federal government safety audits of United States motor carriers. We find that hazardous materials firms are five times larger, in terms of annual fleet miles, than non-hazardous materials haulers, and are more likely to be general commodity carriers. Based on Poisson regression analysis, firms that carry hazardous materials exclusively have a crash rate 11% higher than comparable firms that do not carry these commodities, and a rate of fatalities and serious injuries that is 22% higher. Firms that carry hazardous materials in combination with general freight, have a crash rate that is 18% higher and a fatality and injury rate that is 24% higher.

Among hazardous materials carriers, crash rates decline with firm size. Private carriers are safer than for-hire carriers. Haulers of gases in packages and liquids in tanks have the highest crash rates. Carriers of hazardous wastes have the lowest crash rates. Firms classified as "unsatisfactory" in safety audits by the federal government have a crash rate 50% worse than other firms, though these crashes do not result in a higher incidence of fatalities and injuries.

6. 1987 Conference on Transportation Deregulation and Safety in Trucking and Aviation.

On June 23, 1987 the Transportation Center of Northwestern University convened a three-day conference on the implications for safety of two pieces of legislation, the Airline Deregulation Act of 1978 and the Motor Carrier Act of 1980. These Acts had the effect of reducing the control of the federal government, and of carrier rate associations on the conditions of competition in the two industries. In particular, the regulatory reforms embodied in the two Acts allowed: greater freedom of entry into the two industries; greater freedom of entry into, and of exit from, particular markets; and greater freedom of individual rate making. The Acts significantly increased the influence of market forces on the prices charged for air and truck service, and the profitability of individual firms. Increased rate competition between motor carriers had direct effects on the rates charged by railroads for the movement of high value goods, and indirect effects on all other tariffs. The regulatory reform bills were passed because it was felt that increased competition would lead to more efficient operations and lower rates in the two industries, while not compromising safety, or seriously compromising quality of service.

View the cover, executive summary, list of contents, and introduction to the conference proceedings [11 pages, 858 kb PDF].

The results of the conference were published in a book:

Leon N. Moses and Ian Savage (editors) (1989). Transportation Safety in an Age of Deregulation. (New York: Oxford University Press.)
[Publisher Information]

The conclusions of the conference are available in the summary report on the conference which was included in the proceedings of the conference published by Northwestern University's Transportation Center in 1988 [26 pages, 136 kb PDF].