The Hertford loop line[1][2] (also known colloquially as the Hertford Loop) is a branch of the East Coast Main Line, part of the Northern City Line commuter route to London for Hertford and other Hertfordshire towns and an occasional diversion route for the main line. The line is part of the Network Rail Strategic Route 8, SRS 08.03 and is classified as a London and South East Commuter line.[3]
History
The line was opened in three stages between 1871 and 1924. The first section called the Enfield Branch Railway was developed by the London and York Railway and went from Wood Green to Enfield.[4] In 1898, a plan was approved to extend the line north to Hertford and Stevenage, in order to relieve congestion on the main line without having to widen the Welwyn Viaduct. Work started in 1905 and Cuffley was reached on 4 April 1910. The construction of two major viaducts and the Ponsbourne Tunnel (at 2,684 yards or 2,454 metres, the longest in the eastern counties of England and the last to be built by traditional methods), combined with World War I shortages of men and materials, delayed the opening of the route to Stevenage until 4 March 1918. Then it was single track and for goods services only. The line finally opened to passengers on 2 June 1924 when a new station at Hertford North was opened.[5] The line was electrified in 1977.[6]
The line was also used frequently during the Second World War as the Welwyn/Digswell Viaduct was at high risk from bombs.
Grade-separated junctions connect each end of the northbound track with the main line. All stations are long enough to accept two, three-car (20m) EMUs. Not all stations are long enough for newly introduced 6-car EMUs, but their walk-through design allows for access.
Tunnels and viaducts
Major civil engineering structures on the Hertford Line include the following.[8]
Network Rail used Beacon Rail owned Class 313 unit 313121 as a test vehicle for ERTMS on the Hertford Line.[9] The plan involved resignalling a 5+1⁄2-mile (8.9 km) section of the double track route to allow existing passenger and freight services to work bi-directionally over the up Hertford loop line, freeing the down line for ERTMS tests and evaluation.[10]
References
^ abNetwork Rail (2 December 2006). London North East Route Sectional Appendix. Vol. Module LNE1. p. 46. NR30018/01a.
^Quail Map 2 - England: East [page 24] Feb 1998 (Retrieved 2014-04-12)
^A Regional History of the Railways of Great Britain (Vol. 3 Greater London), H P White, David & Charles Ltd 1971 (Pages 166-7)
^A Regional History of the Railways of Great Britain (Vol. 5 The Eastern Counties), D I Gordon, David & Charles Ltd 1977 ISBN0-7153-4321-1 (Pages 123-4)
