Development of measuring apparatus for contact wire wear by sodium vapor lamps

In electric railways in Japan, inspection cars are running at commercial speed, in order to measure wear of contact wires. We have developed an apparatus to measure the contact wire wear with a light source of sodium vapor lamps of simpler mechanism and smaller size than that of current apparatus. This apparatus measures the width of wear surface by an optical method, and converts it into a residual height. This apparatus has been used for JR Yamagata Shinkansen in JR. On the other hand, we miniaturized this apparatus further, and developed an overhead contact line inspection system for rail-and-road cars. The results of field tests show that it can be used at a standard deviation of measuring error of 0.3 mm in daytime.