Destinations include Hertford North, Welwyn Garden City, Stevenage, and Cambridge, and in peak hours, additional services run to Peterborough and King's Lynn.
In 2009, rolling stock was transferred from other lines to allow additional services and longer trains to be run.
[6] The Inner Suburban Lines to Welwyn Garden City and Hertford North were electrified in 1976 with Class 313 EMUs.
Rapid growth on the route, especially on the Cambridge Line resulted in consultation on a new service pattern,[8] which was then implemented at the timetable change in Spring 2009.
Proposals as part of the original electrification work envisaged a new underpass here and land was set aside for its construction.
A new plan[10] and subsequent application for an order[11] to build a flyover was approved, and construction was completed in June 2013.
Although this takes trains over a longer distance, it removes the need for them to dwell at Hitchin – sometimes for several minutes – awaiting a path across the tracks of the main London-Peterborough route, thus decreasing the overall journey time to Cambridge in many instances.
The scheme improves the punctuality and reliability of both the London-Cambridge and London-Peterborough routes, because Peterborough-bound stopping trains are no longer delayed if running closely behind a Cambridge service being held at Hitchin waiting to cross the flat junction.
Trains diverging from the Great Northern Route at Belle Isle will join the 'core' St Pancras - Farringdon - City Thameslink - Blackfriars section of the existing Thameslink route and then serve stations across Surrey, East Sussex, Kent, and West Sussex.
[16] During peak hours, Great Northern runs 5 'limited stop' services in each direction between Peterborough and London King's Cross, with calls at Huntingdon, St Neots, Biggleswade and Stevenage only.
[16] In addition, during peak hours, Great Northern runs 3 'limited stop' services in each direction between Letchworth Garden City and London King's Cross, with calls at Hitchin, Knebworth and Welwyn North only.