Derailment of an overhead gantry for the erection of precast concrete girders

This article explores the reasons for the derailment of an overhead gantry during construction of a precast concrete girder viaduct. Inasmuch as the accident occurred on the last out of 13 spans on one of two nominally identical parallel bridges in which no prior anomalies had been detected, a detailed forensic investigation was in order. The parallels among numerical calculations, experimental findings, eyewitness accounts and reconstruction of the accident sequence lent support to the identification of the most likely hazard scenario. The underlying causes were associated with less than optimal interfacing and data exchange among the actors involved in viaduct construction. The study showed that in addition to efficient quality assurance strategies, clearly defining each actor’s tasks and responsibilities is of cardinal importance in preventing construction worksite accidents.