To understand the effects of insulating fastener components of subway rail on the fastener-to-earth transition resistance and further reduce the stray current

the elastic bar type III fastener is taken for example to establish an equivalent circuit of the fastener-to-earth transition resistance according to the leakage current path from rail to earth. The influences of bulk conductivity and surface conductivity of each fastener’s insulating component on the transition resistance is calculated and the relationship between the transition resistance and each component is obtained. Experiments are conducted to verify the simulation results. It is found that: the bulk resistance of the fastener group insulation material is107 times as much as the surface insulation resistance

and the surface insulation resistance plays a decisive role for the transition resistance;the surface insulation resistance is inversely proportional to the surface conductivity

the surface insulation resistance between the pad under rail and the pad under iron pad is merely 20 percent that of the gauge block

and the condensation on material surface will reduce the transition resistance by half or 2/3;the key to improve the transition resistance of the fastener is to increase the surface insulation resistance between the pad under rail and the pad under iron pad. The research results in this paper provide theoretical support for further improving the track-to-earth transition resistance.