Dynamic Forces at Square and Inclined Rail Joints: Field Experiments

Abstract

Insulated rail joints (IRJs) are widely used in signaling and broken rail identification systems. Track deterioration adjacent to IRJ is frequent due to excessive dynamic forces generated at IRJs by the repetitive passage of the ongoing traffic. Hence, they exhibit low service life and are considered high-risk elements and maintained through high standards. With a view to increase operational speed and the annual operational throughput, many improved structural designs have been proposed, of which inclined IRJs are the focus of this paper. To compare noise, vibration, and adjacent sleepers’ vertical displacement of square and 30° and 45° cut joints, a series of field tests have been carried out in the Tehran-Karaj urban metro track. Results show that sleepers in the vicinity of 45° cut joint have less vertical displacements compared to that of 30° and square cut joints. Peak root-mean square (RMS) values of acceleration signatures of 30 and 45° cut joints are almost half the value for square joints. Noise test results show that sound level of 30° cut IRJ is less than that of 45° and square cut IRJs by 2 and 6 dBs, respectively. Also, the noise level of 30° cut IRJs is less than that of 45° and square cut joints by 1 and 3 dBA, respectively.