In the United States vehicle weight limits are set by laws and regulations enacted at the state and federal levels. On interstates the maximum allowable gross vehicle weight is 80,000 lbs. States use different rules for permitting overdimensional and overweight (OD/OW) vehicles, and most have carve outs that exempt specific commodities from standard weight limits. This results in a complex legal and regulatory landscape that enforcement personnel can find difficult to negotiate. This report discusses strategies that can be adopted in the state of Kentucky to improve enforcement and mitigate infrastructure damage caused by OD/OW loads. After presenting a thorough review of laws pertaining to vehicle weight limits at the national and state levels, the report presents the results of a nationwide survey administered to agency staff directly involved in weight limit enforcement. Survey respondents reported that OW trucks inflict a disproportionate amount of damage on pavements and bridges that permitting fees and fuel taxes are insufficient to ameliorate roadway damage caused by these vehicles, and that commodity exemptions and staff shortages make enforcement a challenging proposition. In addition to sharing many of the opinions of agency staff elsewhere, Kentucky personnel said that many bridges and roadways are not designed to withstand repeated loads of 80,000 lbs. of gross vehicle weight, heavier vehicles with commodity exemptions are especially damaging to collector and local roads, and that enforcement efforts need to be redoubled. Recommendations for improving weight limit enforcement in Kentucky cover areas such as legislation (e.g., reducing the number of commodity exemptions, using axle-based weight limits), highway design, enforcement and judicial practices, and permitting and fees. Implementing these recommendations can help Kentucky modernize and standardize its enforcement efforts.

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© 2021 University of Kentucky, Kentucky Transportation Center

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The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky, the Kentucky Transportation Center, the Kentucky Transportation Cabinet, the United States Department of Transportation, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. The inclusion of manufacturer names or trade names is for identification purposes and should not be considered an endorsement.