Hitchin Grade Separation



Value £2.9 Million
Duration 30 Weeks
Main Contractor Hochtief
Client Network Rail

The Hitchin Flyover is a grade-separated single-track railway flyover on the Great Northern Route near Hitchin, Hertfordshire, England, which carries the Down Cambridge Flyover line over the East Coast Main Line. Constructed in less than a year it was built to increase the throughput at Cambridge Junction, 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.

The main bulk of the works consisted of a new composite steel reinforced viaduct some 800m in length with 22 spans. The bridge was erected over the ECML with minimal disruption to the line by constructing the entire section of structure over the railway in night time possessions. The reinforced concrete deck was cast in situ using a suspended falsework system and Paraslim modules to form the soffit for the deck allowing large sections of deck to be cast vastly reducing programme requirements.

The 22 sets of piers and crossheads supporting the flyover were constructed of modular steel shutters allowing quick turnarounds on the pier construction. In addition to the deck works there were 2 abutments, a large section of retaining wall and a farm access subway built simultaneously with the deck.