An Assessment of the Safety and Efficiency of Log Trucks with Increased Weight Limits on Interstate Highways in Minnesota and Wisconsin

Abstract

Design standards for the Interstate Highway System in the US are generally higher than those on other roads within most states, making it the safest road system in the US. Federal law prevents states from enforcing vehicle weight limits on interstate highways that deviate from established Federal weight limits or state-specific grandfathered weight limits or exceptions. While state gross vehicle weight (GVW) limits for trucks that haul logs exceed federal interstate highway limits in all major timber-producing states that don’t have grandfathered limits, state-legal weight log trucks are not allowed to travel fully loaded on the interstate Trucks hauling logs at legal state limits must travel on state, county, township and local roads. On these routes trucks pass through towns/cities, school zones and encounter on-coming traffic and intersections. All these encounters increase the risk of an accident.

This study compared the relative importance of the transport of raw forest products by trucks to the top five non-timber commodities and the fatality rates of log trucks to other heavy trucks in the lower 48 states, compared available national road damage cost estimates for interstate and non-interstate roads and assessed the impact of relaxing interstate weight limits on hauling distance, travel time, safety, pavement damage and CO2 emissions for hauling timber along three travel corridors in Wisconsin and Minnesota.

Logs are an important commodity in many states but generally represent a minor percentage of the tonnage of commodities hauled by trucks. On a per load basis, log trucks have a lower fatality rate than other heavy trucks in 83% of the lower 48 states, including in those states that have higher GVW allowances on the interstate due to grandfathering. Due to the higher design standards, pavement damage costs are lowest on interstate highways as compared to other road types.

Allowing state-legal, loaded log trucks access to federal interstate highways would improve the overall safety and efficiency of timber transportation while reducing pavement damage costs and CO2 emissions along the three travel corridors. The safety benefits generally exceeded the efficiency gains. Overall, study findings suggest that allowing state-legal, loaded log trucks to operate on interstate highways would improve the safety and efficiency of timber transportation in Wisconsin and Minnesota.