Higher Highway Weight Limits Ahead?

Future freight demand, fuel savings could spur change.

A new study prepared for the Soybean Transportation Coalition suggests higher highway weight limits could help lower fuel costs and increase efficiency as demand for freight is projected to grow over the next three decades.


Current weight limits on semi-trucks (80,000 pounds GVW) have been in place since 1975, but rising fuel costs, periodic labor shortages, and increasing congestion on the nation’s roadways have prompted some lawmakers to consider increasing those weight limits to levels approaching 100,000 lbs.


The regulations have important economic consequences because trucking accounts for about 80% of expenditures on freight transportation in the United States, and trucking costs are influenced by the amount of cargo that can be transported per shipment. 


The U.S. Department of Transportation projects the volume of freight demand by all modes of transportation (air, truck, rail, and water) to increase from 21.2 billion tons in 2007 to more than 37.2 billion tons in 2035, a 75% increase.


The STC analysis highlights five independent projections for the future growth of freight movement across the four major modes (truck, rail, water, and air).  Each projection predicts the highest growth rate for air, followed by truck, rail, and water.  Air freight transportation is largely confined to high value, low density products with a very time-sensitive delivery. Most freight – including agricultural products – is transported via truck, rail, and water. 


Among these remaining modes, demand for trucking is consistently projected to grow the most. Truck volumes are expected to increase from 12.9 billion tons in 2007 to 22.8 billion tons in 2035, a 77% increase. Currently the intensity of truck freight volume is 10,500 trucks per day per mile. By 2035, use intensity will increase to 22,700 trucks per day per mile with the most heavily used portions of the system handling up to 50,000 trucks per day per mile.


Potential savings

What are the potential savings by allowing 97,000-lb. semis over our nation’s highways and interstates?


The STC analysis reveals that adopting a 97,000-lb. weight threshold will annually save approximately 16.9 million trips, reduce miles driven by 2.7 billion, and save 221 million gallons of diesel fuel by 2020, says Mike Steenhoek, STC Executive Director.


Currently Congress is considering a bill called the “Safe and Efficient Transportation Act of 2009,” which would grant states the option of raising the current 80,000-lb. weight limit to 97,000 pounds for trucks equipped with a sixth axle, with the assessment of a new dedicated fee to support bridge repair and maintenance. The bill currently enjoys broad bipartisan support.

According to AgTEC (Agricultural Transportation Efficiency Coalition), passage of the bill would bring U.S. truck-weight limits closer to Canadian and European standards. 

"AgTEC's proposal to raise gross vehicle weight limits on the Interstate System reflects conclusions the Federal Highway Administration and several state DOTs have reached independently," says Richard Lewis, President of the Forest Resources Association, an AgTEC member. 

The Wisconsin Truck Size and Weight Study, which the Wisconsin Department of Transportation published in January, concludes, "Taking into account the total bridge costs and the ability to operate on the Interstate, the most successful new configuration, in terms of net benefits is the six-axle 98,000 semi trailer, which generates the highest savings in transport costs, safety, and (lower) congestion."

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