A trade group representing major retailers, including Target and Home Depot, submitted a comment to the Department of Transportation requesting they “modernize” federal vehicle weight limits. That could mean heavier trucks on the interstate, including in Missouri.
With the current piece of legislation governing America’s highways set to expire next September, lawmakers are discussing different strategies for updating trucking regulations. The largest of those proposed weight increases would bring the federal weight limit up to 91,000 pounds with the addition of a sixth axle, up from the current limit of 80,000 pounds.
Jeff Reed is a cattle rancher in Williamsville and the president of the Missouri Cattlemen’s association. He said Missouri's current system, which has stricter limits on interstates than on state routes, pushes ranchers to use smaller roads for transporting cattle. Standardizing the limit, he said, would mean less time on the road for his animals and fewer large vehicles on two-lane roads.
“The idea would be to get more of that heavier traffic back on the interstate system and be safer for everyone,” Reed said.
Critics of the proposed increase argue that heavy trucks disproportionately damage infrastructure, which puts the burden of higher weight limits on taxpayers.
Bill Buttlar is a civil engineering professor at the University of Missouri who researches paving materials. While many factors impact the lifespan of a road or bridge, he said vehicle weight is “probably number one." Civil engineers can design roads to accommodate heavy trucks, he said, but they can’t always predict how limits will change in the future.
“We're doing a massive investment right now on the I-70 corridor, and that's designed on the current load limits,” Buttlar said.
Much of the impact of that extra weight on roads is mediated by the addition of another axle, which distributes weight more evenly throughout a trailer. But Buttlar said another axle doesn't change the impact heavy trucks can have on bridges, where the full weight of the vehicle has to be supported either way.
He said the relationship between weight and road damage is exponential, meaning even small increases in vehicle weight limits can cause massive changes in the quality of that infrastructure.
“If you were to double that load, it's not as simple a thing as to say that the life of the road would be cut in half. It would be cut way more than that,” Buttlar said. “You would use most of the life of that road.”
Even still, Reed said inconsistent standards across state and federal roads can make it easy for business owners who rely on trucking to accidentally break the law.
“Overall it'd be a better system,” Reed said. “Right now it's not the same, so you make a turn on the interstate and all of a sudden you're illegal.”
In Missouri, the current weight limit on interstates is 85,500 pounds. Reed said the 91,000 pound limit would allow him to add an extra eight to 10 calves on most of his trailers, most of which already have a sixth axle. Like other industry leaders, Reed said allowing more cargo per vehicle would mean taking fewer trips — and fewer trucks on the road overall.
Buttlar said he's skeptical that would happen.
“If the price of hauling something went down, because you could put more weight on a truck, it might shift some of the freight off of the railroads and onto the roads,” he said. “And then you have very congested roads with even heavier trucks. And as a motorist, you're still dodging the same number of trucks, but the road is bumpier, and so it's like lose-lose.”
If the federal limit were increased, the decision to adopt the change would be left to each state's transportation agency. The Missouri Department of Transportation was unable to comment within the time frame of this article.
