State-of-the-art review of bridges under rail transit loading

A state-of-the-art review on the global behaviour of bridges under rail transit loading is presented. Of interest is a synthesis of recent technical findings that can bridge the gap between research and practice. The literature review revealed that structural responses have been evaluated and finite-element and analytical models developed. Identification techniques appear to be useful to extract the dynamic characteristics of rail bridges. Impact increases static load in conjunction with dynamic amplification; however, it tends to converge with train speed. The impact force of a wheel-track system is affected by train weight and speed, rail irregularities and rail type. A number of parameters are associated with rail break. The occurrence of rail breaks increases dynamic load allowance and could cause train derailment. Longitudinal forces induced by thermal loading are another important factor in understanding rail-structure interaction. Contrary to highway bridges, limited effort has been made for railway bridges in terms of reliability investigations and the calibration of load and resistance factors. Scarce information is available on bridge responses associated with light rail trains. Several transit agencies have developed design guidelines using their own live load models. A standard live load model for light rail transit is required to achieve uniform design outcomes.