The Hertford loop line (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. 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. 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 , 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 Hertford North Station was opened. The line was electrified in 1977. The line was also used frequently during the Second World War as the Welwyn/Digswell Viaduct was at high risk from bombs. Route and settlements served The Hertford Line leaves the East Coast Main Line at Langley junction, just south of Stevenage. Watton-at-Stone, serving the village of Watton-at-Stone Hertford North, serving the town of Hertford Bayford, serving the villages of Bayford and Brickendon Cuffley, serving the villages of Cuffley, Northaw and Goffs Oak Crews Hill, serving the village of Crews Hill Gordon Hill, serving Gordon Hill and Forty Hill, also close to Chase Farm Hospital. Enfield Chase, serving Enfield Town Grange Park, serving Grange Park Winchmore Hill, serving Winchmore Hill Palmers Green, serving Palmers Green Bowes Park, serving Bowes Park, Bounds Green and Wood Green It rejoins the East Coast Main Line at Wood Green South junction, north of Alexandra Palace railway station. Operations Great Northern operates suburban services along the Hertford Line between London King's Cross or Moorgate, and Stevenage, Watton-at-Stone or Hertford North. Occasionally, London North Eastern