The Tyne and Wear Metrocars are a fleet of light rail vehicles manufactured by Metro-Cammell for the Tyne and Wear Metro in North East England between 1978 and 1981. For operation on Network Rail controlled tracks between Pelaw Junction and Sunderland, they are designated on TOPS as the Class 599. Most were refurbished between 2010 and 2015 by Wabtec Rail at Doncaster Works and are scheduled to be replaced by Class 555 rolling stock from 2023. Design The design of the Metrocars was partly derived from that of the German Stadtbahnwagen B. However, they were built by Metro-Cammell in Birmingham, and were not fitted with the lights and indicators that would have allowed them to run on streets. Each Metrocar consists of two semi-permanently connected coaches mounted on three bogies, with the middle bogie being a Jacobs Bogie. The outermost bogies are powered and the centre Jacobs Bogie, located in the articulated section between both halves is unpowered. The trains make use of rheostatic braking between , with air-operated disc brakes for use during the final stages of deceleration below . All bogies are also equipped with a pair of emergency magnetic track brakes, which can be used to bring a train to a complete stand in as little as from the maximum service speed of . Metrocars have three acceleration steps, and four braking steps, and an additional emergency brake step which drops the emergency magnetic track brakes. Many features of the Metrocar are operated by compressed air which is stored in a reservoir under the driving cab at the front of the train. Features operated by air include: air-operated disk brakes, horn, windscreen wipers and passenger doors, as well as being used to raise the pantograph. As the section between Pelaw and Sunderland on which they operate is part of the Network Rail system, the units were allocated TOPS class 599 in January 2002. Prototypes and test track Prior to opening, two prototypes, 4001 and 4002, underwent several years of testing from June 1975 on a test track in Backworth. The track was built on the route of an old mineral wagonway formerly part of the North Tyneside Steam Railway. It had a two-lane car shed and a mock station platform, along with a short tunnel section which consisted of concrete tunnel segments laid at ground level; the tunnel was later demolished to allow testing of prototype cars