​On July 27, 2023, about 10:18 p.m. local time, Southeastern Pennsylvania Transportation Authority (SEPTA) trolley 9107 derailed at the intersection of Island Avenue and Woodland Avenue in Philadelphia, Pennsylvania, and struck a sport utility vehicle and the Blue Bell Inn.[1]​ Shortly before the derailment, an electronics specialist began operating trolley 9107 from SEPTA’s Elmwood maintenance facility toward an adjoining yard for storage.[2] As the trolley left the facility, the electronics specialist attempted to apply the air brakes to stop the trolley from moving downhill into Island Avenue, but the brakes had been rendered inoperable during maintenance and did not activate. The electronics specialist jumped out of the trolley before the derailment and collision with the sport utility vehicle and Blue Bell Inn. He sustained minor injuries. The sport utility vehicle was occupied by four people, two of whom were transported to a local hospital with minor injuries. The Blue Bell Inn was occupied by one resident, who was not injured. Visibility conditions were dark, but the area was illuminated by ambient and street lighting; the temperature was 84°F with light wind and no precipitation. SEPTA estimated equipment damage to be about $500,000. Longcare Appraisal & Adjustment estimated damage to the Blue Bell Inn to be about $300,000.

​We determined that the probable cause of the derailment of Southeastern Pennsylvania Transportation Authority trolley 9107 was the trolley's movement with inoperable brakes; the electronics specialist operating the trolley was unaware that the brakes were disconnected because of insufficiently documented maintenance procedures. Contributing to the likelihood of the accident were inadequate training resources for maintenance employees and a maintenance shift turnover process that lacked clear communication about the condition of the brakes.​