Longer Combination Trucks

The Intermodal Surface Transportation Efficiency Act of 1991 directed GAO to report on the economic and safety impact of multiple-trailer trucks, known as longer combination vehicles (LCV). Most LCVs are either triple or double trailers that operate at gross weights above the 80,000-pound federal limit allowed on interstate highways, primarily in 14 western states that have "grandfathered" exemptions from the federal weight limits, and on some turnpikes in six other states. While the analyses of benefits from and costs attributable to LCVs are theoretical because of different assumptions, wider use of these combination trucks would reduce annual trucking costs, according to one analysis, by about 3 percent or $3.4 billion. Meanwhile, analyses by the Federal Highway Administration indicate that nationwide use of LCVs on the interstate highway system could require additional investments of $2.1 billion to $3.5 billion to replace bridges, improve interchanges, and provide staging areas for the breakdown and assembly of these vehicles. While limited data on LCVs show they have not been a safety problem where used in western states and on eastern turnpikes, GAO has previously identified operational characteristics of LCVs that could make them a greater safety risk if allowed on more congested highways.

GAO found that: (1) expanding LCV use could increase highway maintenance and construction costs by up to $18 billion; (2) infrastructure changes needed due to expanded LCV use include bridge replacements, interchange improvements, and staging areas for LCV assembly; (3) infrastructure costs could be reduced by limiting LCV expansion to carefully selected routes away from major population areas; (4) expanding LCV use would not divert significant amounts of freight from the railroads; (5) nationwide use of LCV on interstate highways would reduce trucking costs by about 3 percent, which would most benefit large companies that combine small shipments; (6) the use of some types of LCV is not likely to increase because of logistics problems and customer demand; (7) LCV have increased stability problems, slower acceleration when merging into traffic, and lower speeds on grades; and (8) LCV have not been a safety problem in low traffic density areas, but expanding LCV use into more congested areas will require careful analysis, stricter driver qualifications, and better monitoring of LCV operations by state authorities.

Recommendations

Our recommendations from this work are listed below with a Contact for more information. Status will change from "In process" to "Open," "Closed - implemented," or "Closed - not implemented" based on our follow up work.

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