The Ohio Department of Transportation (ODOT) uses the Ohio Hauling Permit System (OHPS) to evaluate more than 335,000 permit loads each year. Many of these permits involve non-standard gauge (NSG) axle loads, meaning vehicles with gauge widths not equal to 6 feet. ODOT currently evaluates these vehicles by applying modifiers to AASHTO live load distribution factors prior to running the automated OHPS analysis process. When analysis results indicate that structures are incapable of carrying a load, ODOT engineers either apply restrictions on the hauling of loads or perform more rigorous and time-consuming evaluations of individual structures.
The modifiers used for the NSG axle loads are based on historical precedent and not supported by research. The purpose of this project was to determine by analysis appropriate modifiers to AASHTO live load distribution factors for prestressed concrete side-by-side box beam, concrete slab, concrete I-beam, and steel multi-beam structures. ODOT engineers would then apply these factors to the automated OHPS to produce more accurate evaluations of NSG axle vehicles.