V, giving a potential difference of 630 V. The single-track line north of Epping, which closed in 1994, is now the Epping Ongar heritage railway. shuttle services operate at weekends between North Weald and Ongar and North Weald and Coopersale. These do not call at Blake Hall, as the station platform was removed by London Transport after the station closed, and the remaining building is now a private residence. The section between Leyton and just south of Loughton is the oldest railway alignment in use on the current London Underground system, having been opened on 22 August 1856 by the Eastern Counties Railway (ECR). Loughton to Epping was opened on 24 April 1865 by the ECR's successor, the Great Eastern Railway (GER), along with the section to Ongar. The Hainault Loop was originally the greater part of the Fairlop Loop opened by the GER on 1 May 1903. The line has three junctions: Woodford Junction is a flat junction north of Leytonstone the branch to Newbury Park descends into tube tunnels under the older route to Woodford west of North Acton there is another burrowing junction separating the lines to Ealing Broadway and West Ruislip. The line has the shortest escalator on the London Underground system, at Stratford (previously at Chancery Lane), with a rise of and, at Stratford and Greenford, the only stations where escalators take passengers up to the trains. That at Greenford was the last escalator with wooden treads on the system until it was replaced in March 2014. They were exempt from fire regulations because they were outside the tunnel system. The line has the shallowest underground Tube platforms on the system, at Redbridge, just below street level, and the sharpest curve, the Caxton Curve, between Shepherds Bush and White City. List of stations Open stations Former stations On the Denham extension, aborted due to its location in a sparsely populated area within the Metropolitan Green Belt: Denham; it was never connected. Harefield Road; it was never opened. Wood Lane; closed 22 November 1947, replaced by White City. British Museum; closed 24 September 1933, replaced by two new platforms at the Piccadilly line's Holborn station. On the shuttle service from Epping to Ongar, closed in September 1994: North Weald; it was first served by the Central line on 25 September 1949, taking over the Great Eastern Railway (GER)'s services. It closed on 30 September 1994. Blake