The Hitchin Flyover is a grade-separated single-track railway flyover on the Great Northern Route in Hitchin, Hertfordshire, England, constructed between 2012 and 2013. It was built to increase the throughput at a congested flat ("at-grade") junction with the East Coast Main Line just north of Hitchin, which put severe constraints on capacity on both that line and the Cambridge Line.
|Hitchin Flat Junction|
Together with the Digswell Viaduct some ten miles to the south, the flat junction just north of Hitchin was a major bottleneck, as northbound trains diverging from the East Coast Main Line towards Letchworth and thence to Cambridge had to cross one northbound (fast) line and two southbound (fast and slow) lines to access the Cambridge Line. Proposals as part of the original electrification work in the early 1970s envisaged a new underpass here and land was set aside for its construction. However, budgetary constraints forced this part of the programme to be abandoned. The land stood empty for many years, but has since been used to provide new housing.
Construction was completed in June 2013. Original plans were to build the embankment using aggregate trucked in from elsewhere, but eventually it was decided to build up the embankment using chalk taken from the nearby Wilbury Hills, low-lying chalk hills forming part of the Chiltern Hills, from less than 1 mile (1.6 km) away, removing the need for lorry movements along public roads. The chalk was quarried from just beyond the ancient Icknield Way, which at this point is a public bridlepath between Ickleford and Letchworth Garden City, and the contractor was required to refill and replant the quarry afterwards.
The scheme has created a new single-track line that diverges from the northbound slow line at a new junction just beyond Hitchin station, using a short embankment section of the former Bedford to Hitchin Line, a section of which was cleared of vegetation and made progressively higher, to form a short ramp. The track is carried over the East Coast Main Line on a newly constructed viaduct and onto a new embankment to join the present Cambridge Line at the newly created Hitchin East Junction, closer to Letchworth.
Although this routing skirts around the flat junction in a curve that takes trains over a physically longer distance, it removes the need for them to dwell at Hitchin – sometimes for several minutes – awaiting a safe path across the tracks of the main London-Peterborough route, thus decreasing the overall journey time to Cambridge in many instances, and never increasing it by more than 40 seconds. The scheme improves the punctuality and reliability of both the London-Cambridge and London-Peterborough routes, the latter 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.
In May 2013, shortly before the Flyover opened, Network Rail together with Garden House Hospice, a local hospice charity, invited people of Hitchin and Letchworth to walk the line as their last chance to see it along the tracks before it opened for service.
On 26 June 2013, passenger services began to use the flyover. Up to three services per day using it during regular service and driver training. The flyover came into full use in December 2013 with the introduction of the new timetable.
The flat junction still is used, since some heavy goods trains cannot use the flyover because of their difficulty in climbing its incline.
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- British Railways Board. "Your New Electric Railway: The Great Northern Suburban Electrification". Retrieved 15 April 2010.
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- Watson, J. P. (6 August 2010). "Network Rail (Hitchin (Cambridge Junction)) Order. Report to the Secretary of State for Transport". Planning Inspectorate. Department for Transport (United Kingdom). Retrieved 28 February 2014.
- "Land north and east of Cadwell Lane and Wilbury Way and west of Stotfold Road, Hitchin (Hitchin Railway Curve)". North Hertfordshire District Council. May 2012. Retrieved 28 February 2014.
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- "First passenger services start using Hitchin flyover" (Press release). First Capital Connect. 26 June 2013. Retrieved 28 June 2013.
- "First Capital Connect December Timetable announcement". Twitter (Press release). First Capital Connect. 26 June 2013. Retrieved 28 February 2014.