Hitchin Flyover

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.

When referring to the at-grade and grade-separated sections of the junction, they are known as Hitchin Flat Junction and Hitchin Flyover respectively; however, the junction as a whole is actually called Cambridge Junction.

History

Cambridge Junction (until 2013)
East Coast Main Line to/from the North   Cambridge line from/to Letchworth   Cambridge Junction Hitchin East Coast Main Line from/to London

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.

A new plan and subsequent application for an order to build a flyover was approved after an Planning Inspectorate report and public inquiry between 11 and 25 May 2010.

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.

Since the embankment materials were locally sourced it also meant that the new embankment was effectively pre-seeded with poppies. This means the entire embankment is covered in red poppies during their flowering season giving the name to the location 'Poppy Bank'.

Present day

Template:Hitchin FlyoverThe 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, though nowadays this is mainly due to lack of driver knowledge on the route. The route was designed so that all, even the heavy freight trains, can use the flyover. This was discussed with the project engineer at the time of opening.

Hitchin flyover rail curve under construction in 2012

In January 2015 the only form of traction not to have used the flyover was electric locomotives, the first steam hauled working being A4 Pacific 4488/60009 Union of South Africa with an Empty coaching stock move before a steam-hauled Cambridge to York tour.