Automatic measurement of the position of the overhead contact wire

For optimum electric traction current collection from overhead electrified lines, the contact wire must be correctly aligned with respect to the track. There is therefore a need for an instrument to give a rapid and accurate reading of the wire position, preferably automatically without contact, both in daylight and in darkness and in all weather conditions. The device should preferably be capable of operating from a moving vehicle (maintenance trolley or service train for example) as well a operating as a portable device for use statically. The accuracy required is about +or-10 mm in both height and stagger. The authors describe the first phase of the development of such a device.<>