FHWA studies LCV use in Western states

| 9/7/2004

At the request of the Western Governors’ Association, the Federal Highway Administration has assessed the impact of lifting the current freeze on longer combination vehicles in 13 states that currently allow the larger vehicles. At this time, the agency does not appear likely to change the current rule.

The report, Western Uniformity Scenario Analysis, addresses the impact of expanded operations assuming that weights would be limited only by the federal axle load limits and the federal bridge formula, with a maximum gross vehicle weight of 129,000 pounds and a length of two 48-foot trailers.

The report finds both positive and negative impacts.

It estimates that total truck traffic would decrease by 25 percent 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 more than 14 billion.

The most dramatic change would be seen in a 76 percent drop in travel by conventional five-axle tractor-trailers. And less than one-tenth of 1 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 percent, 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 FHWA report says safety data is inadequate to fully determine potential impacts upon vehicle safety, and adds that impacts on traffic operations are also an issue.

The largest benefit 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 percent in the region.

The report maintains 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 FHWA concludes, “Strong support from elected officials of states within the region for a change in truck size and weight limits has not been evident to date, and there is no compelling federal interest in promoting changes that are not strongly supported by the affected states.”