Abstract:This paper first expounds some concepts, research status and existing problems of beam-rail interaction of rail bridges, and then discusses the basis, evolution and some differences from railway bridges for the establishment of the minimum longitudinal stiffness of urban rail transit bridges. Based on the analysis and comparison, the effect mechanism of the braking force of the highway vehicle on the track structure in the highway-rail combined bridge is calculated and analyzed. Finally, the opinions and suggestions are put forward on the reasonable value of the limit value of the longitudinal stiffness of the pier and abutment of the rail transit bridge in the subway code.