Effect of Overweight Trucks on Bridge Deck Deterioration Based on Weigh-in-Motion Data

Highway agencies are responsible for the optimal expenditure of taxpayer dollars allocated to highway infrastructure. Truck size and weight are regulated by federal legislation, and every state highway agency has its own legal load limits. In addition, state agencies issue permits for trucks with gross vehicle weights that are above legal load limits. However, the effect of overweight trucks on the service life of bridge structures, especially concrete decks, is not explicitly quantified. Detailed research on deterioration models for bridge decks was conducted. Condition ratings of bridge decks in New Jersey from the National Bridge Inventory were used to derive the deterioration of decks over time, and the expected service lives of decks on different highways were obtained. Weigh-in-motion data from stations in New Jersey were used to extract two data sets: "all trucks" and "legal trucks." The "all trucks" data set was used to develop a deck deterioration model as a function of equivalent wheel load that could be used to estimate expected service life. Finally, bridge life-cycle cost analysis was conducted under two scenarios, one with and the other without overweight trucks, to quantify the economic impact of such trucks on bridge decks. The results indicate that overweight trucks caused more damage on New Jersey state highways than on Interstate highways because of a larger proportion of overweight trucks, heavy wheel loads from overweight trucks, and fewer axles per truck.