Wednesday 9 January 2013

Great Eastern Mainline

The Great Eastern Main Line (GEML, sometimes referred to as the East Anglia Main Line) is a 133 mile major railway line of the British railway system, which connects Liverpool Street in the City of London with destinations in east London and the East of England, including Chelmsford, Colchester, Ipswich, Norwich and several coastal resorts such as Clacton-on-Sea and Walton-on-the-Naze. The main markets are commuter travel to London, particularly to the City of London and Docklands, and business and leisure travellers. The route also provides the main artery for substantial freight traffic between the Port of Felixstowe, Harwich International Port and the rest of Great Britain, via London.

The earliest section of the line operated between Devonshire Street railway station (Mile End) and Romford from 1839 and was built by the Eastern Counties Railway (ECR). The London terminus was then moved to Bishopsgate railway station (initially known as Shoreditch) on 1 July 1840 and the line was extended out to Brentwood in the same year. A further 51 miles of route was added to link London with Colchester by 1843.[3] The original gauge for the line was 5 feet, but this was converted to standard gauge (4′8½″) in 1844.
 
The section of line between Colchester and Ipswich was built by the Eastern Union Railway to standard gauge and opened for passenger traffic on 15 June 1846 and the route to Norwich (Norwich Victoria railway station) opened in 1849.
 
Eastern Counties Railway and Eastern Union Railways and others were amalgamated to form the Great Eastern Railway in 1862.
 
The London terminus was again moved, this time to Liverpool Street on 2 February 1872.
 
The line was ‘grouped’ into the London and North Eastern Railway in 1923 and from 1948 formed part of the Eastern Region of British Railways.
 
In the 1930s a flyover was constructed just west of Ilford to switch the main and electric lines over, to enable main line trains to utilise Liverpool St’s longer west side platforms without having to cross east side suburban traffic in the station throat. The new arrangement also facilitated cross-platform interchange with the Central line at Stratford, services commencing in 1946. Either side of Ilford Flyover, there are single-track connections between the slow and fast pairs of lines, with the westbound track extending to Manor Park railway station and just beyond. A short fifth platform face serves the track at Manor Park, but it sees no normal use. The eastbound track extends as far as Ilford, connecting with that station’s fifth (bay) platform, which does see limited passenger operations. It was also envisaged that a flyover would be built at the country end of Gidea Park Carriage Sidings to switch Southend Victoria trains from the mains to the electrics, instead of at Shenfield London end junction as they do now.
 
Plans were drawn up in the 1930s to electrify the suburban lines from Liverpool Street to Shenfield at 1500 V DC and work was started on implementing this. However, the outbreak of the Second World War brought the project to a temporary halt and it was not until 1949 that the scheme was completed with electrification being extended to Chelmsford in 1956.
 
The British Railways 1955 Modernisation Plan called for overhead line systems in Great Britain to be standardised at 25 kV AC. However, due to low clearances under bridges the route was electrified at 6.25 kV AC. The section between Liverpool Street and Southend Victoria was completed in November 1960. Extensive testing showed that smaller electrical clearances could be tolerated for the 25 kV system than originally thought necessary. As a result it was now possible to increase the voltage without having to either raise bridges or lower the tracks along the route to obtain larger clearances. The route between Liverpool Street and Southend Victoria was converted to 25 kV AC between 1976 and 1980[5] Electrification was extended to Norwich by 1986.
 
In 1986 it became part of Network SouthEast. Between 5 January 1997 and 31 March 2004, suburban and medium distance services were operated by First Great Eastern, while fast mainline services were operated by Anglia Railways. All services are now operated by Greater Anglia.
 
Liverpool Street IECC replaced signal boxes at Bethnal Green (closed 1997), Bow (closed 1996), Stratford (GE panel closed 1997), Ilford (closed 1996), Romford (closed 1998), Gidea Park (closed 1998), Shenfield (closed 1992) and Chelmsford (closed 1994). The system uses BR Mark 3 solid state interlockings, predominantly four-aspect signals and a combination of GEC-Alsthom HW2000 and Smiths clamp-lock point machines.
 
The first signalbox to be closed and transferred to Liverpool Street IECC was Shenfield, which had only opened in 1982. The last boxes to be transferred were at Romford and Gidea Park, and were the oldest of those being transferred, having been opened under the GER/LNER 1924 resignalling scheme.

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