The Federal Highway Administration (FHWA) has taken a first step in harmonizing size and weight limits in accordance with the provisions of the North American Free Trade Agreement (NAFTA), according to information published in the "Federal Register" July 29. The agency is proposing that width-exclusive devices be allowed to project four inches from the side of a commercial vehicle. Currently, the width is limited to three inches.

In October 1999, a NAFTA committee issued a paper on vehicle performance criteria for vehicles that might be allowed to operate in the three NAFTA countries (Canada, Mexico and the United States). The report contained candidate vehicle performance criteria and recommended threshold values. The definition of overall width included, "exclusive of devices or appurtenances at the sides of a truck, tractor, semitrailer, or trailer whose function is related to the safe operation of the vehicle. Such devices may extend no more than 10 centimeters beyond the side of the vehicle." Using accepted conversion factors, 10 centimeters equates to 3.937 inches.

The primary objective of the committee is to seek areas within the broad range of vehicle weights and dimensions that can be harmonized among the participating countries. The FHWA, as an active participant in the activities the committee, is attempting to harmonize size and weight limits where possible. The exclusion of non-property carrying devices, extending up to three inches from the side of a commercial vehicle, is based on agency policy and industry practice that has evolved since the first federal statute describing maximum vehicle width appeared in 1956. However, this three-inch limit itself is not statutory, and thus may be subject to administrative change by the agency.

For more information on the proposal, visit Federal Register.