Development of an Electronic Detection and Warning System to Prevent Overheight Vehicles from Impacting Overhead Bridges

Overheight vehicle impacts with bridges are surprisingly common. The damage from collisions can range from minor to severe, and there is also evidence that some bridges are impacted multiple times, leading to the potential for cumulative damage effects. Thus there is a clear need to attempt to prevent overheight vehicle collisions with bridges. This Synthesis Study provides a review of solutions that exist to detect and forewarn overheight vehicles and thereby prevent a collision, and specifically examines the breadth of available overheight vehicle detection technologies, the commercial availability of such equipment, and the experience of relevant DOTs with installed and functioning systems. The findings of this study indicate that most states have updated their infrastructure to account for overheight vehicles and permanently avoid collisions. The few states that still actively employ overheight vehicle detection and warning systems (OVD&W) tend to use optoelectronic single- or dual-eye infrared detection systems and report that the devices have decreased the amount of damage occurring to their structures. The initial equipment and installation costs of these systems range from a few thousand to twenty-five thousand dollars based on DOT interviews, and on-going maintenance appears minimal. Overall, considering that the only other completely effective option to avoid overheight vehicle incidents is to raise the height of affected structures, or lower the roadway surface, an (optoelectronic) OVD&W system is a relatively inexpensive and effective method for decreasing overheight vehicle accidents. With this in mind, this study provides a guide to the site characteristics that influence both sensor selection and overall OVD&W system design. A simple Equipment Selection Tool is presented to guide system choice, and is demonstrated through a case example centered on the I-65 - I-70 merger location in Indianapolis, IN.