Western Uniformity Scenario Analysis: A Regional Truck Size and Weight Scenario Requested by the Western Governors' Association

Federal Highway Administration2004PDFTech ReportUnited States. Office of Transportation Policy StudiesUnited States. Federal Highway AdministrationUnited StatesSize and weight regulationsVehicle sizeVehicle weightStandardizationIn 2000, the U.S. Department of Transportation (DOT) issued the "Comprehensive Truck Size and Weight (CTS&W) Study." The CTS&W Study analyzed five truck size and weight scenarios varying from a rollback of size and weight limits to nationwide operations of longer combination vehicles (LCVs). The Western Governors' Association (WGA) requested that DOT analyze an additional scenario that would be limited to Western States already allowing LCVs. Specifically, the WGA asked the DOT to analyze a policy option that would allow 13 Western States to harmonize LCV weights and dimensions at levels that meet existing federal axle load limits and the Federal Bridge Formula and that are in accordance with guidelines established by the Western Association of State Highway and Transportation Officials (WASHTO). This report presents the results of this analysis. Both positive and negative impacts of the proposed scenario were discovered. The report estimates that total truck traffic would decrease by 25% in the region, primarily in the long-haul trucking sector. Forecasts for total truck vehicle miles traveled in 2010 would drop from 18.8 billion to a little over 14 billion. The most dramatic change would be seen in a 76% drop in travel by conventional 5-axle tractor semitrailers, and a 44% drop in STAA doubles. Less than one-tenth of one percent of rail traffic would be expected to divert to LCVs. However, the report also finds that the changes in the scenario would affect long-term pavement and bridge costs, and necessitate interchange and other design improvements to accommodate larger trucks. Pavement costs might actually decline by 4%, according to the analysis, because of reduced truck traffic. However, bridge improvement costs are projected to double as states address bridges overstressed by additional weight. Additional costs are also anticipated for improvements to geometric designs to accommodate the longer configurations. The report found safety data inadequate to fully determine potential impacts upon vehicle safety. It also found that impacts on traffic operations are also an issue. The largest benefit found would be reduced shipper costs. If fully implemented in each state, the report estimates that the scenario could save shippers some $2 billion a year, a savings of almost 4% in the region. The report points out that few Western states charge fees that cover the kind of infrastructure costs that would be associated with LCV operations, and recommends that this issue be addressed, so that the increased costs are not passed on to other highway users. The report concludes that, without strong support from state elected officials, which has not been evident to date, the risks of adverse impacts, the divisiveness that might ensue as the current balance is upset, and the further polarization of the issue would outweigh the benefits that might be realized.97