The interstate commercial motor carrier industry, primarily the trucking industry, is an important part of the nation’s economy. Trucks transport over 11 billion tons of goods, or about 60 percent of the total domestic tonnage shipped. Buses also play an important role, transporting an estimated 860 million passengers in 2005. FMCSA estimates that there are 711,000 interstate commercial motor carriers, about 9 million trucks and buses, and about 10 million drivers. Most motor carriers are small; about 51 percent operate one vehicle, and another 31 percent operate two to four vehicles. Carrier operations vary widely in size, however, and some of the largest motor carriers operate upwards of 58,000 vehicles. Carriers continually enter and exit the industry. Since 1998, the industry has increased in size by an average of about 29,000 interstate carriers per year. In the United States, commercial motor carriers account for fewer than 5 percent of all highway crashes, but these crashes result in about 13 percent of all highway deaths, or about 5,500 of the approximately 43,000 highway fatalities that occur nationwide annually. In addition, on average, about 160,000 of the approximately 3.2 million highway injuries per year involve motor carriers. The fatality rate for trucks has generally decreased over the past 30 years but has been fairly stable since 2002. The fatality rate for buses decreased slightly from 1975 to 2005, but it has more annual variability than the fatality rate for trucks due to a much smaller total number of vehicle miles traveled. (See fig. 1.) In an attempt to reduce the number and severity of crashes involving large trucks, FMCSA was established by the Motor Carrier Safety Improvement Act of 1999. FMCSA assumed almost all of the responsibilities and personnel of the Federal Highway Administration’s Office of Motor Carriers. The agency’s primary mission is to reduce the number and severity of crashes involving large trucks and buses. It carries out this mission by (1) issuing, administering, and enforcing federal motor carrier safety regulations and hazardous materials regulations; (2) providing education and outreach for motor carriers and drivers on the safety regulations and hazardous materials regulations; (3) gathering and analyzing data on motor carriers, drivers, and vehicles; (4) developing information systems to improve the transfer of data; and (5) researching new methods and technologies to enhance motor carrier safety. FMCSA relies heavily on the results of compliance reviews to determine whether carriers are operating safely and, if not, to take enforcement action against them. (See fig. 2.) FMCSA conducts these on-site reviews to determine carriers’ compliance with safety regulations that address areas such as testing drivers for alcohol and drugs, insurance coverage, crashes, driver qualifications, driver hours of service, vehicle maintenance and inspections, and transportation of hazardous materials. Due to resource constraints, FMCSA and its state partners are able to conduct compliance reviews on only about 2 percent of the nation’s estimated 711,000 interstate motor carriers each year. It is FMCSA’s policy to target these reviews at carriers that have been assessed by SafeStat as having the highest risk of crashes, have been the subject of a safety-related complaint submitted to FMCSA, have been involved in a fatal accident, have requested an upgraded safety rating based on safety improvements, or have been assigned a safety rating of conditional following a previous compliance review. Based largely on the number and severity of violations that it identifies during compliance reviews, FMCSA assigns carriers safety ratings that determine whether they are allowed to continue operating. FMCSA can take a range of enforcement actions against carriers with violations, including issuing notices of violation informing carriers of identified violations and indicating that additional enforcement action may be taken if the violations are not corrected; issuing compliance orders directing carriers to perform certain actions that FMCSA considers necessary to bring the carrier into compliance with regulations; assessing fines for violations of the safety regulations; fines require carriers to pay a specific dollar amount to FMCSA; placing carriers or drivers out of service for unsatisfactory safety performance, failure to pay a fine, or imminently hazardous conditions or operations; revoking the operating authority of carriers for failure to carry the required amount of insurance coverage; pursuing criminal penalties in some instances when knowing and willful violations can be proved; and seeking injunctions from a court for violations of a final order such as an out-of-service order. FMCSA has 52 division offices that partner with the 56 recipients of its Motor Carrier Safety Assistance Program grants. FMCSA also funds and oversees enforcement activities, including compliance reviews, at the state level through this grant program. The program was appropriated $188 million, or about 38 percent, of FMCSA’s $501 million appropriation for fiscal year 2006. In fiscal year 2006, FMCSA conducted 9,719 compliance reviews, and its state partners conducted 5,463 compliance reviews. SafeStat assesses carriers’ risks relative to all other carriers based on safety indicators such as their crash rates and safety violations identified during roadside inspections and during prior compliance reviews. A carrier’s score is calculated on the basis of its performance in the following four safety evaluation areas: The accident area reflects a carrier’s crash history relative to other motor carriers based on data from states and MCMIS. The driver area reflects a carrier’s driver-related safety performance and compliance relative to other motor carriers based on driver violations identified during roadside inspections and compliance reviews. The vehicle area reflects a carrier’s vehicle-related safety performance and compliance relative to other motor carriers based on vehicle-related violations identified during roadside inspections and compliance reviews. The safety management area reflects the carrier’s safety management performance relative to other motor carriers based on safety-management-related violations (such as failing to implement a drug or alcohol testing program) and hazardous-materials-related violations identified during compliance reviews and on closed enforcement cases resulting from compliance reviews. A motor carrier’s score is based on the carrier’s relative ranking, indicated as a value, in each of the four safety evaluation areas. This value can range from 0 to 100 in each area, and any value of 75 or greater is considered deficient. Any value of less than 75 is not considered deficient and is not used in calculating a SafeStat score. FMCSA assigns categories to carriers ranging from A to H according to their performance in each of the safety evaluation areas. (See table 1.) Although a carrier may receive a value in any of the four safety evaluation areas, the carrier receives a SafeStat score only if it is deficient in two or more safety evaluation areas. The calculation used to determine a motor carrier’s SafeStat score is SafeStat score = 2 x accident value + 1.5 x driver value + vehicle value + safety management value As shown in the formula, the accident and driver areas have 2.0 and 1.5 times the weight, respectively, of the vehicle and safety management areas. FMCSA assigned more weight to these areas because accidents and driver violations correlate relatively better with future crash risk. In consultation with state transportation officials, insurance industry representatives, safety advocates, and the motor carrier industry, FMCSA used its expert judgment and professional knowledge to assign these weights, rather than determining them through a statistical approach, such as regression modeling. Based on the results of a compliance review, FMCSA assigns the carrier a safety rating of satisfactory, conditional, or unsatisfactory. The safety rating, which is distinct from a carrier’s SafeStat category, reflects FMCSA’s determination of a carrier’s fitness to operate safely. FMCSA issues out-of-service orders to carriers rated unsatisfactory, and these carriers are not allowed to resume operating until they make improvements that result in an upgraded safety rating. Carriers rated conditional are allowed to continue operating, but FMCSA aims to conduct follow-up compliance reviews on these carriers. FMCSA assigns safety ratings based on a carrier’s performance in six areas. (See table 2.) One area is the carrier’s accident rate, and the other five areas involve its compliance with regulations. The five regulation-based areas are (1) minimum insurance coverage and procedures for handling and evaluating accidents; (2) drug and alcohol use and testing, commercial driver’s license standards, and driver qualifications; (3) driver hours of service; (4) vehicle parts and accessories necessary for safe operation; inspection, repair, and maintenance of vehicles; and (5) transportation of hazardous materials. Regardless of a carrier’s safety rating, FMCSA can assess a fine against a carrier with violations, and it is more likely to assess higher fines when these violations are serious. FMCSA uses a tool to help it determine the dollar amounts of its fines. Federal law requires FMCSA to assess the maximum allowable fine against a carrier for each serious violation of federal motor carrier safety and commercial driver’s license laws if the carrier is found to have a pattern of such violations or a record of previously committing the same or a related serious violation. SafeStat identifies many carriers that pose high crash risks. However, modifications to FMCSA’s policy that carriers have to score among the worst 25 percent of carriers in two or more safety evaluation areas to receive high priority for a compliance review and focusing more on crash risk could result in the selection of carriers with a higher aggregate crash risk. FMCSA recognizes that SafeStat can be improved, and as part of its Comprehensive Safety Analysis 2010 reform initiative, which is aimed at improving its processes for identifying and dealing with unsafe carriers, the agency is considering replacing SafeStat with a new tool by 2010. FMCSA’s policy for prioritizing carriers for compliance reviews based on their SafeStat scores results in FMCSA’s conducting compliance reviews on carriers with a higher aggregate crash risk than carriers that are not selected. As a result, FMCSA’s prioritization policy has value as a method for targeting high-risk carriers.