In The News

"TRB Urges Higher Weight Limit"
Transport Topics - May 20, 2002

The Transportation Research Board called on Congress to allow tractor-trailers of 90,000 pounds on six axles and trailers 33 feet long in doubles configurations to operate on federal highways under state supervision, possibly leading to reform of federal truck size and weight standards.

The federal weight limit on the interstate and primary highway system is currently 80,000 pounds. A 14-member committee of state transportation officials and university researchers organized by the TRB offered these and other recommendations as a way to "improve the efficiency of truck freight transportation" and "mitigate the costs of truck traffic to the public," according to a TRB report released May 16.

"We discovered a lack of information about the costs and benefits of larger trucks and the impact of regulations," James Poirot, the committee's chairman and retired chairman of the engineering consulting firm CH2M Hill Inc., said in a prepared statement.

The report, requested by Congress, said Congress should charter an independent federal institute to collect data and study truck dimensions and weights apart from the emotions and controversies that surround the issues.

The committee concluded that concerns about the safety of larger trucks and their effect on state highway maintenance budgets and motor carrier competition are not always based on facts. Safety critics argue that bigger trucks cause more accidents because they are harder for drivers to control. Highway officials worry that heavier rigs cause roads to wear out faster.

"This new institute would be on the spot to make some politically charged recommendations to the secretary of transportation," said Joseph Morris, the committee's staff director. Morris said the institute would not have any regulatory authority and that it should work in collaboration with the Department of Transportation.

The TRB report also recommended that states be allowed to substitute user fees for some size and weight limits to control road maintenance costs.

Federal regulations enacted in 1982 established a maximum weight of 80,000 for combination vehicles on roads built with federal money, set vehicle width at 102 inches and authorized twin-trailer operations throughout the interstate system. The regulations also limited the standard semitrailer to 48 feet in length and twin trailers to 28½ feet each.

All 48 continental states, largely at the behest of shippers, have since invoked their own authority to allow single trailers up to 53 feet in length. Also, many states, especially in the West, continue to permit longer combination vehicles, including triple trailers.

Many shippers and some motor carriers continue to call for regulatory changes to accommodate higher-capacity vehicles as a way of reducing shipping costs. American Trucking Associations has long pushed for the elimination of federal gross weight limits, preferring that trucks be controlled by a combination of axle-weights and a bridge tolerance formula. ATA also supports a proposal for a 97,000-pound, six-axle tractor-trailer.

But truckers are not united in the quest for bigger trucks.

Many carriers and owner-operators say they cannot afford to buy new, larger trailers to meet shippers' expectations of moving more freight at the same rate. Dean Cotton, president of the Mississippi Trucking Association, said motor carriers in his state would fight the proposal.

"Since 1990 we've been opposed to any additional size or weight anywhere in America," Cotton said.

Despite advances in technology, the research board said federal size and weight regulations have been significantly revised only twice in the past 46 years. This has led, the report said, to some larger trucks bypassing the interstates to avoid size limits. Accidents and road deterioration are more likely when trucks travel on secondary roads, committee members said.

In 1998, as part of the Transportation Equity Act for the 21st Century, Congress asked TRB to study size and weight regulations and recommend changes. The committee based its conclusions on past truck size and weight studies, other published information and comments of interested parties.

At the request of the Western Governors Association, the Federal Highway Administration is now studying what would happen to the environment, safety, roads and bridges and the economy were western states to standardize their size and weight rules for longer combination vehicles that operate under special permits.

"We'd like Congress to issue an exemption allowing Western states to make their LCV regulations uniform," said Darrin Roth, director of highway operations for ATA. Weight limits for LCVs range from 105,500 pounds to 129,000 pounds in the West, with some states, notably California, banning their use altogether.

As for the standard tractor-trailer, a sixth axle would reduce pavement wear by spreading the vehicle's weight more evenly across the road surface, the TRB report said.

The report added that two 33-foot trailers can turn at intersections without encroaching any further on opposing lanes than tractor-trailers and maybe more stable than shorter double-trailers.

Under the TRB proposal, states would voluntarily decide whether to allow the longer double-trailer and 90,000-pound combinations. Trucking companies would apply for permits to participate in the evaluations and receive temporary exemption from federal size limits.

TRB is part of the congressionally chartered National Academy of Sciences.

By Eric Kulisch
Transport Topics Staff Reporter