Forensic Inquiry into Derailment of a Launching Gantry

Abstract

Bridge building entails considerable risk, as attested to by the relatively frequent occurrence of worksite accidents. In the accident reported on here, an overhead gantry derailed during the construction of the last of 13 spans on one of two nominally identical parallel bridges composing a precast concrete girder viaduct. As no prior anomalies had been detected, the structure was the object of a detailed forensic inquiry. The most likely hazard scenario was inferred from the mutually reinforcing findings gleaned from numerical calculations, experimentation, eyewitness accounts, and reconstruction of the accident sequence. Organizational flaws such as less-than-optimal interfacing and data exchange among the actors involved in viaduct construction were observed to be among the major underlying causes. The study showed that effective quality-assurance strategies, fluent worksite actor intercommunication, and a clear definition of tasks and responsibilities are of cardinal importance in preventing accidents.