Ruislip Depot
A major part of this was extensions to the Central Line, both in the east, to Leytonstone, Woodford, Epping and Ongar, and in the west from North Acton Junction to Ruislip.[1] The extensions, which would create a route mileage of 45 miles (72 km),[2] meant that new depots would be required for the extra trains needed, and they were to be located at Hainualt and Ruislip.However, the land there was at a low level, and in order to raise it up, some 220,000 cubic yards (170,000 m3) of chalk infill was delivered by rail and spread over the area.[4] The depot was nearly finished by 1939, but with completion of the whole project delayed by the war, it was used as a factory, making anti-aircraft guns,[5] and was also used to store spare and withdrawn rolling stock.[6] Once hostilities had ended, work resumed on the western extension, much of which was constructed on bridges and viaducts, to carry it over a succession of roads, railways and canals.[7] London Transport was the pioneer user of welded rail in the United Kingdom, having bought their first flash butt welder in 1937 and installed it at Lille Bridge depot.The depot at Lillie Bridge was cramped, and in 1969 London Transport decide to build a fully automated plant at Ruislip for flash butt welding of long rails.The Schlatter welding machine, which was moved from Northumberland Park when the plant was constructed, uses a single-phase electrical supply at 14 volts and 40,000 amps.[20] An additional 20 cars of 1992 Stock were purchased for the Waterloo and City Line, then operated by Network SouthEast, and were delivered to Ruislip depot in three batches during March 1993.They were known as uncoupling non-driving motor cars, and were fitted with an automatic Wedglock coupler, with a shunting controller mounted in the end bulkhead.It was originally intended that this would be formed of 8-car articulated units, with the ends of two cars carried on a single bogie, but rolling stock requirements were reassessed when authorisation to build the Heathrow extension of the Piccadilly Line was obtained.[28] In 2012, some of the depot buildings were covered with a green roof, as part of an assessment to see if rainfall could be attenuated, and thus relieve drainage problems.Subsequent railtours normally started from Uxbridge, easily reached from Ruislip via the connection to the Piccadilly Line tracks beyond the welding plant.34 cars left the depot in Autumn 1988, en route for the engineering works at Eastleigh, where they were refurbished for use on the Island Line.