Developing Efficient State Load Rating Vehicles Using a Heuristic Approach

Abstract

States may allow vehicles to exceed US federal weight limits off the interstate system, but state-specific load rating vehicles are developed to ensure that bridges can carry such vehicles safely. However, if the load effects of state rating vehicles are not similar to those of the vehicles operating in the state, the load factors required for the safety of some bridges may be too large for others, resulting in unnecessary remediation that may include retrofitting, posting, or even closure. In this study, a quantifiable measure of load rating efficiency is used to analyze the load effects of rating and operating vehicles on a wide range of bridges. Using this measure of efficiency, a novel heuristic approach is used to identify nearly optimal rating loads that envelope the load effects of state operating vehicles, potentially reducing the need for remedial action. To illustrate, the approach is used to develop new rating loads proposed for the state of Indiana. This approach may be combined with further analyses to assess the potential economic impact of new rating vehicles.