A contact wire is an electrical wire that hangs over railroad tracks to supply electricity to railroad vehicles via their pantographs, which contact the wire. It wears gradually due to the contact with the pantographs. To ensure safe operation, it is vital to measure the remaining thickness of the contact wires regularly and to manage them to ensure that the wire does not reach the status in which replacement is needed.

In the past, the remaining thickness of contact wires was managed by a variety of methods, including measurement using wear monitoring systems mounted on railroad vehicles ("vehicle-mounted systems") and workers directly measuring the wires using micrometers. Vehicle-mounted systems can measure wires while the vehicles are operating, but it is necessary to process a huge amount of data collected every day. The accuracy of micrometer measurements is high, but they must be done at night when trains are not operating. The scope of wire that can be inspected at one time is limited. For these reasons, the railroad industry sought a method of easily checking the wear status of contact wires during the day.

Developed by Proterial Cable Solutions, the contact wire with wear grooves indicating the expiration of the wire’s service life has a single groove referred to as a "wear groove" on each side of the lower part of the contact wire. The grooves are positioned to ensure that their appearance changes when the contact wire wear reaches the criterion for its replacement. This enables workers to determine whether or not replacement is necessary when visually inspecting the grooves from the ground using binoculars or similar tools.

This shape innovation has made it possible to visually inspect contact wires during the day without using measuring equipment to determine if their condition requires that they be replaced. This reduces the costs and working hours required for wear management and facilitates systematic replacement in line with the progression of wear. Proterial Cable Solutions will work to facilitate the broad use of the GT-SNNS170SQ contact wire with wear grooves indicating the expiration of the wire’s service life to help ensure the safety of railroad infrastructure and increase the efficiency of maintenance work by preventing wire breakage and extending the service life of contact wires.