Knowledge Resources

Side object detection systems (SODS) have the potential to improve the safety of transit buses by helping transit operators avoid collisions with objects on the side of the bus. Data from the Federal Transit Administration (FTA) showed that almost half of all transit bus collisions occur on the side, costing an average of $3,660 in property damages per side collision. The transit operating environment presents challenges for a collision detection system because buses range into and out of proximity to side objects of various types, from signs, other vehicles, poles, and pedestrians. (In contrast, collision warning systems for personal vehicles are designed for high-speed environments and more or less constant distances to other vehicles.)

The only commercially available SODS for transit buses entered the market in 2004. Designed to operate at speeds below 15 mph and with lane changes greater than 15 mph, the SODS detects objects on the side of the bus through ultrasonic transmitters and receivers, and alerts the driver with visual and audible warnings. The U.S. DOT sponsored an independent evaluation of the SODS as deployed in transit buses in the fleets of three cities (District of Columbia, Cleveland, Ohio and Salt Lake City, Utah) to determine the system’s user acceptance and return on investment.