Would increasing U.S. truck weight limits make sense?

 A B-Double trailer in Australia with side panels allowing for side load.  (Photo: Dean Croke)

A B-Double trailer in Australia with side panels allowing for side load. (Photo: Dean Croke)

Demand for cheap products is rising, and a national "just-in-time" delivery network has placed trucking companies under economic pressure to move heavier and heavier loads. Also, in light of the freight capacity crunch, and Trump’s infrastructure proposal still on the table, FreightWaves thought it would be worth asking the question: Would an increase in trucking’s federally mandated 80,000-pound total weight limit do any good? Turns out, it's a topic with a wide variety of opinions. We gathered together some background, analysis, and opposing points of view on this surprisingly complex subject.

Why and how the limits currently work

Since the establishment of the Interstate Highway System in 1956, the federal government has regulated truck size and weight limits. The purpose is to protect interstate commerce by ensuring that carriers can operate under a set of minimum uniform regulations that allow them to cross state lines without having to abide by different regulations state-to-state, and to protect the federal investment in highways and bridges and ensure safe operation of motor vehicles.

Federal weight regulations apply only to the Interstate Highway System, while length and width regulations apply to the National Network, a 200,000-mile truck network designated by states. Federal law requires states to allow reasonable access from these highway systems to points of loading and unloading, and to fueling and rest locations. On all other roads, states determine size and weight regulations. 

Major changes in federal law occurred most recently in 1982, when the minimum weight limit was increased from 73,280 pounds to 80,000 pounds, and in 1991, when Congress passed a law freezing the operation of longer combination vehicles (LCVs). LCVs are multi-trailer trucks with more than two trailers with a gross weight that exceeds 80,000 pounds, or where any trailer exceeds 28.5 feet. The most recent attempt was in 2015, called the Safe, Flexible, and Efficient (SAFE) Trucking Act (H.R. 3488), which a push was made for a higher federal limit of 11,000 pounds, which would include an extra axle installed on the 53' trailers.

Currently, the 53-foot trailer with 45,000 pounds is the max that can be put in a trailer provided the overall gross weight doesn't exceed 80,000 pounds, and that load weight when combined with the weight of the truck and trailer, can register no more than 12,000 pounds over the front axle, 34,000 pounds over the drive axles and 34,000 pounds over the rear axle tandems. But to muddy the waters, there are already specialized carriers on the nation's highways that are permitted to exceed the weight limit. 

The debate

The ATA has asked for reform to these limits. They argue that heavier weighted vehicles--so long as they're appropriately proportioned with axle distribution--would actually make things safer and more efficient.

The ATA’s current position isn’t likely to make change anytime soon. Their current lobbying tactic is to take on the Federal one-size-fits-all regulation, and go state-by-state. But as BiTA president, Chris Burrus, says, “That approach is not likely to get very far.” The problems are obvious, and the U.S. has been “down that road before,” which is why it shifted to a federally mandated approach in the first place.

“It’s been a big debate since as long as I can remember,” says Burrus. “On the LTL side of things they’ve lobbied for extended doubles and triples, and they’ve argued for increased efficiency. Within truckload there’s a camp that wants more weight, but there’s another side that says, ‘We’re not going to get paid’ because shippers won’t pay more per load.”

Burruss points out that actually in today’s current climate of tight capacity, shippers would pay more because they have to. But in a loosening capacity market, shippers wouldn’t; they’d just lower the rates. Also, on the economic side of things, Burruss says that many fleets resist changes because they’d have to buy entire new fleets in order to keep up with their competitors.

The last time the ATA pushed forward with legislation, they landed on a compromise, which Burruss refers to as “88 on 5.” It means you wouldn’t have to modify your trailers but could get another 8,000 pounds, and that was appealing to many. However, they never took out the “97 on 6,” language—which would have left the door open for competitors to change their fleets and get a leg up on the competition. The legislation died on the floor.

As for safety, “The LCVs are safer if you’re way out west, but in the density of the population in the east it’s different,” says Burruss. “Congress has not had an appetite. Then, of course there’s the rail lobby, and other highway safety advocacy groups—some of which are funded by the rail lobby.” Collectively, it adds up to enough resistance for it to make it through the labyrinthine legislative process, it would take an enormous amount of political will and capital. 

For the Truckload Carrier's Association (TCA), it comes down to a matter of how to focus on the real solution. "The truckload industry is heavily invested in the 53. It would antiquate the 53' trailer almost overnight. Not necessarily making them bigger, just adding an axle and installing the braking," says David Heller, TCA vice president of government affairs. "Plus, your fuel costs would go up." Even if you were able to figure out a way with shippers to actually get paid more for the extra freight, instead of by the load, "you'd still have to add in the backhaul." In other words, extra fuel costs could be covered by extra pay for the freight, but you'd have to figure in the cost of taking the larger trailer back, especially if, in all likelihood, it would be transporting considerably less on its return. 

It’s been a big debate since as long as I can remember.

The overhead cost for carriers

In 2015, when the TCA did their calculations for retro-fitting the five-axle operations, they estimated the approximate cost to add the extra axle and lengthen (for dry vans) or replace (for refrigerated trailers) the axle slide bar, to range between $3,000 and $4,800 per trailer. The additional axle adds between 2,000 and 2,500 pounds to the trailer’s weight and has an average 0.5 mpg negative impact on fuel economy. This is what is commonly referred to in the industry as “rolling resistance” and occurs with the additional axle, regardless of whether or not the trailer is loaded.

To accommodate 11,000 additional pounds for the 91,000/6 configuration, most carriers would also need to upgrade their tractors. Tractors with larger, higher torque-rated engines and heavier-duty kingpins would likely be necessary. Retrofitting current tractors with the upgrades could cost approximately $10,000 per tractor. New tractors with the necessary features for 91,000/6 would cost an additional $5,000 to $7,000 more than tractors with standard (350-400 hp) engines with some estimates placing the premium as high as $20,000.

Additionally, carriers would likely want to consider switching to tires with higher ratings (going from G-rated to H-rated) and altering their tire maintenance schedules. H-rated tires would incur an increased cost of the price of new tires. Based on these figures, it could cost most carriers anywhere between $8,000 and $24,800, per tractor trailer, to upgrade their equipment to haul the additional 11,000 pounds. Because of the extra weight of the third axle, the additional weight allotment would actually be closer to 8,000 to 8,500 pounds.

"The bottom line is we need to fix our infrastructure, and we need to find drivers, not just drivers, but qualified drivers. When you get into these additional weights, you get into a lot of convoluted things," Heller says. 

The rural infrastructure problem

According to the ATA, all states allow truck size and/or weight limits above generally applied federal limits. This is usually “due to a grandfather right or exemption.” For the most part, the higher limits are authorized for trucks operating off the Interstate system, since federal law does not permit states to authorize higher weight limits on the Interstate system. The bad news is that non-Interstate highways are neither as safe nor as well constructed as Interstates, thus it really is less safe. Most states could attest to this. The rural parts of the U.S. are often hit the hardest.

“Many of the roads were not designed to sustain heavy truck traffic,” Cesar Quiroga, senior research engineer with the Texas A&M Transportation Institute (TTI), told Roads & Bridges. “In south Texas, for example, there are many farm-to-market roads, which were designed to handle the occasional combine or 18-wheeler. But now you have a massive influx of heavy loads, and many of these roads have been destroyed pretty quickly.”

According to Quiroga, it is a simple matter of calculable percentages. “When you look at the number of new horizontal wells in south Texas against the percentage of road miles that are considered below good, there is a strong correlation between the number of [oil] drills and pavement degradation. This relationship is not linear. If you double the weight of a vehicle, the impact on the pavement is not double; it is exponentially higher than that. A lot of people do not realize how critical this is. Worse, some of these trucks are not kept to a legal limit, which [in Texas] is 80,000 pounds, with a by-permit overage of 5% to 84,000 pounds. But since the impact is not linear, that ratio does not go up by 5%. It’s more like 25%. So, if you go up to 100,000 pounds, which some of these trucks do, what do you get?”

You get the result of an economy essentially busting at the seams, and roads that can't sustain it. 

"If you have to treat a road in five years instead of eight, or in eight years instead of 12, there's a real cost impact," says Judith Corley-Lay, the chief pavement management engineer for North Carolina's transportation department. At the request of state lawmakers, a decade ago Corley-Lay analyzed truck traffic in the state to determine the cost of overweight trucks. What she found was startling: Heavy trucks cost the state an extra $78 million per year. And that figure was really just a rough estimate, based on average road types and some guesswork to fill in gaps in traffic data.

A 2018 study, "Effect of Heavy Trucks with Large Axle Groups on Asphalt Pavement Damage" showed that more weight does more damage, but better axles do less damage. The authors write, "The results indicate that while fatigue damage increases with increasing number of axles within an axle group, the normalized damage (i.e., relative to the load a given axle carries) decreases with increasing number of axles for multiple axle groups, making these larger axle groups less damaging when considering their economic impact."

The bottom line is we need to fix our infrastructure, and we need to find drivers, not just drivers, but qualified drivers. When you get into these additional weights, you get into a lot of convoluted things.

The Australia example

Limiting the carrying capacity of trucks reduces the efficiency of freight deliveries, increasing costs across the supply chain. “Compared to truck operators in Europe, standard U.S. tractor-trailer combinations are 33% longer but carry 34% less weight per foot of vehicle length. The difference is due to U.S. trucks being predominantly conventional versus European cab over tractors--a hood is equivalent to about two rows of pallets in terms of available load space.

"It’s almost the same in Australia where length limits are also based on overall bumper-to-bumper length," says FreightWaves Chief Analytics Officer, Dean Croke. But when compared to the relative freedom they have in a geographically-diverse continent, such as Australia, it’s not hard to see the U.S.’s competitive disadvantage when it comes to long combination vehicles (LCVs) that carry far more weight per foot of vehicle length on the same interstate highway system as the U.S.

 B-Triples run on interstates in remote areas of Australia - same 4-lane design as here. This truck hauls 44 4’x’4’ pallets of freight and offers a lot of operational flexibility. Operators can drop the front trailer and go everywhere an 18-wheeler does in the U.S., or if things get really quiet with freight, you just drop the front 2 half-trailers and haul the 45’ rear trailer around as a normal tractor-trailer combo. One B-Triple is almost the equivalent of two 18-wheelers on the road, so fewer trucks means more revenue per mile for LCV operators, less accidents and fewer greenhouse emissions. Engine Power is key as the combo to has to maintain close to the same road speed as other road users so there’s isn’t a major speed differential that creates a safety hazard.  (Photo: Dean Croke)

B-Triples run on interstates in remote areas of Australia - same 4-lane design as here. This truck hauls 44 4’x’4’ pallets of freight and offers a lot of operational flexibility. Operators can drop the front trailer and go everywhere an 18-wheeler does in the U.S., or if things get really quiet with freight, you just drop the front 2 half-trailers and haul the 45’ rear trailer around as a normal tractor-trailer combo. One B-Triple is almost the equivalent of two 18-wheelers on the road, so fewer trucks means more revenue per mile for LCV operators, less accidents and fewer greenhouse emissions. Engine Power is key as the combo to has to maintain close to the same road speed as other road users so there’s isn’t a major speed differential that creates a safety hazard. (Photo: Dean Croke)

“Here you’re paid by the mile, so there isn’t really an incentive to load more weight per mile,” says Croke, who was also a long-haul, over-the-road trucker and company manager in Australia. Weight limits are a subject he can get passionate about.

“Here, because of space issues, massive distribution centers in the dry-van truckload sector have hundreds and hundreds of docks lined up side-by-side where trailers are rear load, making it difficult to optimize every cubic foot of space. In Australia, you’re paid by how much you put in the trailer and as a result have some of the most creative and productive trailer designs in the world. They side and rear load trailer, and even reefers have side panels that move, allowing frozen freight to be side loaded more efficiently. A lot of interstate long combination trailers have mezzanine floors allowing freight to be stacked to the roof without damaging freight underneath.”

“In a normal 53' trailer you can load 26 4’x4’ pallets,” Croke observes. “By way of comparison, in Australia, a 9-axle B-Double with the same level of city access and swept path or turning radius to an 18-wheeler, can fit 84 pallets using mezzanine floors and double drop trailers. When you’re paid by the pound of freight you haul you get very creative about maximizing every square inch of interior trailer space.”

In Australia, you’re paid by how much you put in the trailer and as a result have some of the most creative and productive trailer designs in the world.

Also, even while such LCVs could carry tremendous volumes of more freight, they’re just as easy to drive because the drivetrain rating and engine horsepower are exponentially more powerful, and because of creative trailer design features that close up the gap between the other trailers, the swept path is amazingly tight. “Even my gigantic 9-axle B-Double, weighing in at 140,000 pounds was approved to drive in every single city and could actually get into more places than a long-hooded conventional tractor with a 48’ trailer,” says Croke.

But how could such behemoths actually make the roads safer? "Fewer trucks carrying more weight driven by well qualified drivers means less exposure and fewer accidents. LCVs also generate more revenue and profit per loaded mile and from an environmental perspective, fewer and newer trucks means less greenhouse emissions,” says Croke. It also means less wear and tear because of the fewer trucks.

Comparing Australia to the U.S. isn't necessarily an apples-to-apples comparison, but it does elicit some creative approaches. The resistance to change comes from the legitimate issues of current infrastructure already in place, public perception, and the array of vested interests with competing points of view.

Stay up-to-date with the latest commentary and insights on FreightTech and the impact to the markets by subscribing.