Certain business interests are lobbying for H.R. 3372, which would create a “pilot project” to allow any state to increase truck weights from 80,000 pounds to 91,000 pounds for up to 10 years on its interstates. This bill was passed out of the House Transportation and Infrastructure Committee in May, 2023. The goal, according to the legislation: to track crashes involving these heavier trucks, including injuries and fatalities. This does nothing more than turn interstates into test tracks and motorists into guinea pigs.

As the Virginia Department of Transportation stated when analyzing potential involvement in a pilot project:

Safety must remain a primary consideration. Increases in crash rates among the heavier trucks could occur and although a decrease in safety would be a trigger for discontinuation of the pilot, any injuries or loss of life resulting from the pilot would be unacceptable.”
(Virginia Department of Transportation, 2018)

In 2016, the U.S. Department of Transportation (USDOT) delivered its three-year Comprehensive Truck Size and Weight Limits Study Report requested by Congress. That report found that heavier trucks had serious safety problems and would impose additional costs to our highway infrastructure. The Department recommended that Congress not approve any heavier trucks.[1]

“Pilot Project” for Heavier Trucks Means Experimenting with Motorists

A “pilot project” for heavier trucks is misguided and dangerous because of the threat to public safety and damage to infrastructure. So-called “pilot projects” amount to little more than experimenting with heavier trucks on public roads and bridges with motorists. The information they seek is the number of crashes, including injuries and fatalities involving heavier trucks. USDOT and the Transportation Research Board (TRB) have recommended better ways of obtaining this information without further endangering motorists or damaging our infrastructure.

A Safe Alternative

If proponents are serious about collecting more comprehensive information about the impacts of heavier trucks, they should support the comprehensive research plans initiated by USDOT[2] and TRB.[3] Conducting test track operations of bigger trucks and improving the collection of crash and travel data in the states where heavier trucks already operate is the logical next step as opposed to expanding the operation and increasing the dangers. Specific recommendations include the following:

  • Reinstitute and expand the collection of higher-quality, impartial data nationwide (i.e., TIFA and VIUS), including VMT, and implement a uniform crash report form that accurately collects the number of trailers and axles, truck weight and length, and road type where the crash occurred.
  • Collect and analyze data on the impacts of bigger-truck operations on local roads and bridges.
  • Conduct operational tests of bigger-truck configurations at test track facilities, fully evaluating vehicle dynamics in real-world conditions.

Heavier Trucks Are More Dangerous Trucks

More crashes. 91,000 pound, six axle trucks had a 47 percent higher crash rate than 80,000 pound, five axle trucks in limited state testing. 97,000 pound trucks had even higher crash rates, from 99-400 percent higher than 80,000 pound, five axle trucks.[4]:

More severe crashes. The severity of a crash is determined by the velocity and mass of a vehicle. If its weight increases, so does the potential severity of a crash. Any increase in crash severity increases the likelihood of injuries becoming more serious or resulting in fatalities.

More likely to roll over.
Heavier trucks tend to have a higher center of gravity because the additional weight is often stacked vertically. Raising the center of gravity increases the risk of rollovers.[5]

Increased wear and tear. Increasing the weight of trucks causes additional wear and tear on key safety components. The 2016 USDOT study found that trucks weighing over 80,000 pounds had higher overall out-of-service (OOS) rates and 18 percent higher brake violation rates compared to those at or below 80,000 pounds.[6] This is especially important because a 2016 study by the Insurance Institute for Highway Safety found that trucks with any out-of-service violation are 362 percent more likely to be involved in a crash.[7]

Heavier Trucks Would Cause Significant Infrastructure Damage

Bridges don’t care about axles – bridge damage is a function of gross vehicle weight. The USDOT study examined interstate and US highway bridges and found thousands of structures that would have to be repaired or replaced to accommodate 91,000 pound trucks. A recent report that evaluated local bridges the USDOT did not examine found more than 72,000 bridges that are not rated to safely handle 91,000 pound trucks. These bridges would cost $60.8 billion to replace, leaving taxpayers to foot the bill.[8]

Heavier interstate weight limits will not take trucks off of local roads

No truck trip begins or ends on the interstate system. These trucks would operate on all roadways. In fact, 44% of truck traffic operates off the interstates today.[9] The vast majority of state laws allowing heavier trucks on local roads will not conform with a 91,000 pound, six axle pilot program, meaning a pilot program will do nothing to take heavier trucks off of local roads. In fact, this pilot project will increase pressure on state legislatures to increase truck weight limits on local roads, creating serious safety and infrastructure problems.

Previous research shows heavier trucks are dangerous to motorists and damage infrastructure

Along with the most recent studies from USDOT, VDOT and IIHS, other studies have found similar dangers over the years. These include reports from the Wisconsin Department of Transportation,[10] the Transportation Research Board,[11] and the University of Michigan Transportation Research Institute.[12] Given these concerns, additional data should not be collected using methods that puts lives at stake.

[1] USDOT; 2016. Comprehensive Truck Size and Weight Limits Study, Final Report to Congress

[2] Ibid

[3] Transportation Research Board; 2019. Research to Support Evaluation of Truck Size and Weight Regulations

[4] USDOT; 2016. Comprehensive Truck Size and Weight Limits Study, Final Report to Congress

[5] USDOT; 2000. Comprehensive Truck Size and Weight Study

[6] USDOT; 2016. Comprehensive Truck Size and Weight Limits Study, Final Report to Congress

[7] Insurance Institute for Highway Safety; 2016. Crash Risk Factors for Interstate Large Trucks in North Carolina

[8] Bailey, Harvill et al; 2023. The Impacts of Heavier Trucks on Local Bridges

[9] Bureau of Transportation Statistics; 2020. Vehicle Miles Traveled by Highway Category and Vehicle Type

[10] National Center for Freight & Infrastructure Research and Engineering; 2009. Wisconsin Truck Size and Weight Study

[11] Transportation Research Board; 1990. Truck Weight Limits: Issues and Options

[12] University of Michigan Transportation Research Institute; 1988. Analysis of Accident Rates of Heavy Duty Vehicles.