The DV's equipment includes a video-based system utilising image recognition to look for defects such as missing clips. The DV also houses a non-contact overhead line monitoring system, which utilises lasers to measure the position of the wires in relation to the rails the train is on. High-powered white lights and cameras also enable the wear of the contact wire to be monitored. The wear is measured as the width of a strip on the underside, where the pantographs come into contact and wear away the cable. If the original thickness of the cable is known, this can be converted into a percentage of remaining area, which in turn when related to a maximum allowable wear can give an estimate of the remaining life.