Tony Gee was employed by Hochtief (UK), as part of a partner alliance, to undertake the GRIP 5 detailed design of a new grade separated junction between Down East Coast Main Line (ECML) and Down Cambridge Line to the north of Hitchin Station. Tony Gee’s scope included an 850m long, 29 span viaduct, accommodation overbridge, embankment earthworks and drainage.
The viaduct is steel-concrete composite construction, consisting of simply supported decks and 2 and 3 span continuous decks with a 425m horizontal radius. Due to the orientation of the bridge to the ECML tracks the piers adjacent to the ECML are highly skewed. The spans adjacent and over the ECML were installed during a series of possessions, limiting the disturbance to the ECML.
A range of environmental measures formed part of the works, including the provision of beetle banks, hibernacula, secondary ponds and extensive landscaping and planting to reduce or mitigate the effects of the scheme.