On August 22, 2017, about 12:11 a.m. local time, a southbound Southeastern Pennsylvania Transportation Authority (SEPTA) single light-rail passenger car (car 155) carrying 42 passengers on the Norristown High Speed Line (NHSL) collided with another SEPTA single light-rail passenger car (car 148), which was unoccupied and stopped at passenger platform 1 of the 69th Street Transportation Center station (69th Street station) in Upper Darby, Pennsylvania. The 43 persons on board car 155, including the operator, suffered non-life-threatening injuries and were transported to local medical facilities. Both cars remained on the rails and upright. SEPTA estimated the damage to the equipment to be $331,680. The weather at the time of the accident was 79°F with light rain.
The probable cause of this accident was an intermittent anomaly in the braking system of car 155 that degraded its stopping performance on approach to the 69th Street Transportation Center station, resulting in the collision with car 148.