A coalition of 20 national organizations is asking Congress to oppose measures that would allow larger tractor-trailers on the nation’s roads, citing potential damage to local infrastructure, as lawmakers prepare legislation setting transportation priorities for the next several years.

In a letter dated Jan. 28, the groups argue that proposals to raise the current 80,000-pound weight limit for trucks on interstate highways to 91,000 pounds or more would increase road costs and reduce safety.

The broad coalition includes local government groups such as the National Association of Counties and the U.S. Conference of Mayors, as well as the Teamsters, AAA and the Association of American Railroads.

“We wanted to get right out of the gate with our partners and let Congress know that we’re still watching for exemptions to be proposed in the reauthorization bill,” said Emily Mills of the Coalition Against Bigger Trucks, which organized the letter. “It’s really the biggest opportunity that proponents of bigger trucks have to get something across the finish line.”

The coalition argues that proposals to allow heavier trucks — including a 91,000-pound, six-axle pilot project — would amount to an unfunded federal mandate. Legislation to raise weight limits typically does not include funding to cover the additional wear and tear on roads and bridges.

“That creates a big problem on the backs of taxpayers when it comes time to pay for these proposals,” Mills said.

Local infrastructure experts warn that heavier trucks would accelerate the deterioration of bridges that are already struggling under current weight limits.

Kevan Stone, the executive director of the National Association of County Engineers, said many bridges were built decades ago for traffic patterns and loads far lighter than today’s.

“There are bridges today that were built 30, 40, 50, even 100 years ago that were never designed to support the weight of the trucks today,” Stone said. “That’s why you still see bridge postings in some states, and in other cases, trucks are simply unable to cross the bridge.”

In 2025, the National Association of County Engineers partnered with the National Association of Counties for a study on the effect of larger trucks on America’s infrastructure. The report found that, depending on the truck configuration, between 65,157 and 82,457 local bridges nationwide could be put at risk if Congress authorizes heavier trucks on interstate highways.

The estimated cost to replace those bridges ranges from $70.6 billion to $98.6 billion, depending on the proposed gross vehicle weight.

“We really need to preserve the infrastructure projects we have,” Mills said. “And the road safety piece of this is another enormous component.”

Safety advocates also cite rising traffic fatalities involving heavy trucks as a reason to reject heavier vehicles.

“Law enforcement will tell you that now is not the time to bring bigger trucks to the roads, as the number of deaths year over year has increased significantly,” Mills said.

Zach Cahalan, the executive director of the Truck Safety Coalition, said large-truck fatalities now exceed 5,000 deaths annually, representing a 62 percent increase since 2009.

“You don’t have to be a physics major to understand that when you increase the weight and size of trucks, you increase stopping distances and make them harder to control,” Cahalan said. “You’re not only increasing crash rates, but also the severity of the crashes.”

Supporters of heavier trucks argue that modern six-axle configurations distribute weight more evenly and could improve efficiency.

Rep. Dusty Johnson, R-S.D., has backed a limited increase in truck weights for states that opt in, citing supply-chain demands and a shortage of truck drivers.

“Data shows trucks with six axles reduce road wear and tear, have more brakes than a typical five-axle tractor-trailer, and are shown to have a one-foot shorter braking distance,” Johnson said last year.

The Shippers Coalition has dismissed opposition as “fear mongering,” arguing that a 91,000-pound limit with an additional axle could enhance roadway safety.

Supporters of the increased weight limit also note that moving more products on fewer trucks could lower transportation costs and consumer prices. Given Americans’ concerns about the cost of living, the move makes sense, they argue.

Requests for comment from Johnson’s office and the Shippers Coalition regarding the January letter were not returned.

As Congress prepares to rewrite federal transportation policy, critics say lawmakers face a choice: protect existing infrastructure investments and public safety, or risk higher long-term costs by allowing heavier trucks on already strained highways.

“This debate isn’t theoretical,” Stone said. “It’s about whether local communities will be forced to pay more — and whether American drivers will be put at greater risk — because of decisions made in Washington.”

Chris Woodward writes about industry and technology for InsideSources.com.