Most of the damage to U.S. roads and bridges comes not from passenger cars but from heavy trucks, with the most common big rig weighing in at 80,000 pounds — almost as much as a Boeing 737. At this weight, heavy trucks only pay for about 80% of their damage to roads and bridges, with other taxpayers and motorists covering the rest. As truck weights go up, so does the damage they cause — but the percentage they pay for infrastructure goes down, meaning the rest of us pay more.

Currently, a bill proposed in Congress would establish a “pilot program” for states to test 91,000-pound trucks, a 14% weight increase over the current limit. Here’s a breakdown of the bill, why allowing heavier trucks is a bad idea, and the stakes are high for our infrastructure and the supply chain:

A “pilot project” without end: The bill in question, H.R 3372, would create a program for states to ‘test’ 91,000-pound trucks on their roads — but the catch is that the length of the experiment is 10 years, nothing short-term or “pilot” about it. For reference, 10 years is the average lifecycle of two surface transportation reauthorization bills.

Tale as old as time: Every year it seems Congress is lobbied by groups calling for a federal mandate requiring states to allow heavier trucks, longer trucks or trucks pulling more trailers. They say it will mean fewer trucks, or that the addition of a 6th axle will mitigate infrastructure damage. But…

Bridges don’t care about axles: A 2023 study found that 72,000 local bridges across the country can’t safely handle 91,000-pound trucks and that it would cost $61 billion to replace them. In a foreword to the paper, the National Association of Counties and National Association of County Engineers say, “This research fills a longstanding gap in knowledge on the subject and reveals massive financial costs that would burden counties across the country.”

Where we’re going, we do need roads: Even with a 6th axle distributing the load, 91,000-pound trucks would only pay for about 55% of their damage to roads and bridges according to USDOT. As a reminder, U.S. roads received a “D” grade in the most recent American Society of Civil Engineers Infrastructure Report Card. Pavement damage like rutting and bounce (“dynamic loading” effect”) is still also a function of gross vehicle weight regardless of axles.

Bigger trucks never mean fewer trucks: Since Congress last raised truck weights, the number of trucks registered in the U.S. and the miles they drive have increased by 91%. Raising limits now would mean millions more tons of freight on already crowded highways at a time when we’re not keeping up with existing infrastructure and when the average American already spends 54 hours a year in traffic.

Friends and competitors: Let’s face it, trains need trucks (and vice versa)! Together with ships, this amazing supply chain hauls 61 tons of goods for every American every year. But when heavy trucking effectively receives a subsidy, it alters the competitive landscape—especially when you consider that railroads pay for their own infrastructure without taxpayer help. A weight increase to 91,000 pounds would divert 4.4 million rail carloads and intermodal units annually. That’s 13-20% of rail volume depending on commodity diverting to highways and local roads.

Less rail = more traffic, emissions, taxes: Every ton diverted from rail means higher fuel consumption, more traffic, and worsened transportation emissions. Because rail is 3-4 times more efficient than trucks, trains today move 40% of long-distance freight while contributing only 1.7% of U.S. transportation-related emissions.

Private spending, public benefits: Railroads spend about $23 billion every year on their networks and infrastructure, about six times more than the average manufacturer. This investment has made the U.S. rail network the most efficient and cost-effective in the world, not to mention ASCE’s top infrastructure system across 18 categories. More freight by rail means lower costs for shippers (about one-third less than trucking) and fewer greenhouse gases (75% reduction over trucking).

Research plan: The Transportation Research Board has proposed a “TSW Research Plan” to update USDOT’s 2016 analysis of heavier truck damage, and Congress reaffirmed in 2021 and 2023 that no changes in truck weight or length policy should be made until this research is completed. The so-called “pilot project” the current Congress is being asked to authorize is nothing more than a back-door truck size and weight increase.

Bottom line: Congress should reject proposals to allow longer and heavier trucks, including needless “pilot projects,” that would increase the cost of maintaining highways and bridges, create more highway gridlock, worsen emissions, and divert freight from rail.