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A recent study by researchers at NC State University's Institute for Transportation Research and Education (ITRE) has shown fatal crashes involving combination unit trucks (CUT) in NC for 2005-2009 were more frequent on non-Interstate roadways than on Interstate roadways. While small carriers (those operating fewer than 10 power units) constituted only 17% of all fatal CUT-involved crashes on Interstate roads, small carriers constituted 36% of all fatal CUT crashes on non-interstate roads.

The fatal CUT crash frequency outcomes are the product of the effects of 'risk' and 'exposure.' While it is clear that the fatal crash involvement of small and large carriers differs by class of road with fatal crashes involving small carriers representing a higher percentage of fatal CUT crashes on non-interstate roads, without reliable truck exposure data by vehicle class and road class, it is not possible to specify with confidence the relative contributions of risk and exposure to these outcomes.

Preliminary analyses conducted by ITRE prior to this study had suggested that carrier fleet size might be correlated with a measure of crashes per power unit (a measure of crash risk that can be applied across carriers of different size). The earlier analysis did not differentiate between CUTs and other classes of commercial motor vehicles or between classes of roadway on which the crash took place. Empirical support for such a finding would suggest that smaller carriers may be operating at a higher level of risk in terms of crash involvement than larger carriers, and should perhaps warrant special assistance from the standpoint of safety.

The present study also found that 53 percent of all carriers involved in fatal CUT crashes were domiciled in North Carolina, and that 72 percent of fatal CUT crashes for NC-domiciled carriers (irrespective of fleet size) which occurred on non-interstate roadways occurred, on average, within 50 miles of the carrier's reported base of operation. These data indicate that much of the CUT fatal crash problem, at least in NC, is highly 'local' with respect to the carrier's reported base of operation and service area. This suggests that crash reduction efforts on the part of motor carrier enforcement personnel need to be 'up close and personal' (at the individual troop and troop district levels).

ITRE researchers believe that a similar high level of crash risk may apply to the small fleet operators of single unit trucks (SUTs) that fall between 10,000 and 26,000 lbs GVWR. It is important to remember that SUTs, as a class of vehicle, are not exclusively defined by their GVWR, in that many larger SUTS have GVWRs in excess of 26,000 lbs. The presumed need to address SUT-involved crashes in NC is supported by FMCSA data that show North Carolina has a higher than (US) average rate of 2-axle/6-tire involved crashes (26% state compared to 17.3% federal) . . . according to 2010 data reported online at http://ai.volpe.dot.gov/CrashProfile/V1.ASP .

The North Carolina study of fatal CUT crashes was made possible by the fact that all commercial motor vehicles in excess of 26,001 lbs GVWR that operate in interstate commerce (as well as those involved in the intrastate transport of hazardous materials) have to be registered with FMCSA and to obtain/display a USDOT number on the side of the truck.

FMCSA image showing those state (in green) that currently require all commercial motor vehicles, regardless of whether engaged in interstate or intrastate commerce, register with FMCSA to obtain a USDOT number (source: www.fmcsa.dot.gov)

North Carolina is one of a small number of states that still do not require FMCSA registration of commercial vehicles between 10,000 and 26,000 lbs GVWR involved in intrastate operations with the exception of vehicles transporting 16 or more passengers or transporting a placarded amount of Hazardous material. Commercial vehicles, in the class of 10,000 to 26,000 lbs, consist for the most part of (smaller) single unit trucks (SUTs) as well as trucks which, when pulling a trailer involved in commerce, can exceed 10,000 lbs GVWR. By lying outside the jurisdiction of federal motor carrier enforcement regulations (FMCSRs), the safety benefits of FMCSA's driver/vehicle roadside inspection program and safety data management systems are not being effectively brought to bear upon this class of vehicle and their operators – even though motor carrier enforcement in NC is held responsible for 'all' commercial vehicle crashes above 10,000 lbs GVWR.

The NCSU/ITRE study recommended that all commercial vehicles with a GVWR greater than 10,000 lbs be required to register with FMCSA, regardless of the type of commodity being transported and regardless of whether the commodity is being transported intrastate or interstate. The study recommended a detailed analysis of non-CUT commercial vehicle crashes and that this and all future CMV crash studies include 'all' reported crashes . . . not just fatal crashes. The value of doing so is that it permits a comparison of the relative risks of fatal and/or injury crashes by looking at a particular level of injury involvement as a 'percentage' of total crashes. Only when 'all' commercial vehicles, irrespective of commodity and type of operation (i.e., interstate or intrastate) are registered (with FMCSA and/or a state DOT) can the analysis of
commercial motor vehicle crash data pinpoint where CMV crash reduction efforts should be placed.

The ITRE study of fatal CUT crashes in North Carolina between 2005 and 2009 was conducted in parallel with an analysis of fatal CUT crashes in Virginia for this same time period. The analysis of fatal crashes in Virginia was conducted by researchers at the Virginia Tech Transportation Institute and was funded directly by the Virginia Department of Transportation and Virginia Division of Motor Vehicles. The Virginia analysis revealed similar trends to those in North Carolina.

The results of the combined Virginia and North Carolina analysis efforts suggest the need to increase the focus on 'small' carriers and their operations on non-interstate roads, thereby complementing the overall USDOT focus on rural road safety. It is widely recognized that the 'safety culture' of the large, well established carrier can be quite different from that of the small carrier. Companies operating vehicles in commerce in the 10,000 to 26,000 lbs GVWR range may not consider themselves to be "in the trucking business" but rather to be involved in business operations that simply employ trucks as part of their' primary' business.

It is also recognized that the majority of carriers are, in fact, small carriers in terms of fleet size. A cursory review of the data on 'new entrants' in North Carolina confirms that the vast majority of carriers entering 'the business' are, in fact, small in terms of fleet size. The question arises as to what extent small carriers (experienced or otherwise) are able to incorporate the same technologies and levels of safety management practice employed by larger carriers.

Options to provide increased assistance to smaller carriers include an increased (training) focus by state trucking associations, state Governors Highway Safety organizations, and by motor carrier enforcement at the state and local levels, either through direct enforcement actions where jurisdiction permits or by way of CMV 'awareness' training such as that presently conducted by motor carrier enforcement personnel in North Carolina.

The study also urged roadway design and traffic operations functions at the state DOT level be increasingly aware of the need to accommodate truck travel. In addition, the trend towards the use of 'more productive' (i.e., longer and heavier trucks) calls for early analysis and planning on the ability of North Carolina state roads to safely accommodate such vehicles if they are allowed. The relevance of the results to North Carolina efforts to effectively integrate evolving commercial motor vehicle requirements into the development of a statewide logistics plan is also discussed.

Separate reports will be made available by the respective state DOTs upon completion of final editorial reviews. Principal investigator for the North Carolina portion of the analysis was Dr. Ron Hughes; principal investigator for the Virginia portion was Ms. Alejandro Finsch-Medina. Mr. Robert Clarke served as a consultant to the efforts of both states and assisted in the generation of the final report and recommendations.

The recommendations expressed in the study are those of the research project team and do not necessarily reflect the positions of the respective state department of transportation, state or federal motor carrier enforcement organizations, or the respective state trucking organizations.