抄録
It is important item for maintenance of overhead contact line to manage the state of contact wire wear exactly in electric railways. There is a measuring apparatus using in daytime, but it is so large that it should be installed in a exclusive car. So that, a new type of measuring apparatus has been developed, which is so small as to be installed on the roof of a commercial car. The apparatus has an optical system composed of sodium vapor lamps and CCD linear sensor cameras with optical filters. The new apparatus has been tested in laboratory and in field using a test car. The results show that it can be used at 100km/h speed in daytime, and standard deviation of measuring error is 0.3mm.
