Abstract: In order to reveal the time-dependent temperature distribution in the ballastless track structure on a curve line,a continuous observation of CRTS Ⅱ longitudinal plate-type ballastless track was carried out with temperature sensors.After the statistical analysis of a great amount of measured temperature data,the vertical and horizontal temperature gradients of the track were obtained.The results show that ( 1) the vertical and horizontal temperature distributions of the ballastless track are both nonlinear in the process of heat exchange with the outside; ( 2) the temperature of the track periodically changes with the environment temperature; ( 3) the time corresponding to the maximum temperature delays due to the increase of the distance to the track surface,even presents a 5 h delay at the bottom of the track structure in a comparison with the time on the surface; and ( 4) the vertical temperature gradient is in an exponential distribution,which matches the distribution curve suggested by the design standard for railway bridges and culverts in China.

Key words: railway bridge, track engineering, ballastless track, nonlinear temperature, experimental investigation