This 1km-long cable-stay bridge across the Mersey in the UK conceived by Ramboll, CH2M and Knight Architects officially opens to the public on 14 October
The Mersey Gateway Bridge is part of a 9.5km-long highway corridor project. The Mersey Gateway is one of the UK’s largest civil engineering and infrastructure projects and is situated between the towns of Widnes and Runcorn in the north west of England. The scheme for Mersey Gateway Crossings Board (MGCB) (on behalf of Halton Borough Council) provides significantly increased local and regional highway connectivity and will relieve congestion around the existing Silver Jubilee Bridge, which will be reconfigured for local use. The new route will form an essential link between the Merseyside area and North Wales and Cheshire. The project comprises a new highway corridor with several new and re-configured intersections and, at its heart, a 2.2 km new crossing of the River Mersey.
Projects of this magnitude have a significant impact on the people who use them as well as those who live in their vicinity and Halton Borough Council recognised the importance of good design quality from an early stage. As part of the client’s consultant team, Knight Architects commenced work in 2006 to develop a bridge design to reflect their aims; delivering economic development and higher standards of living whilst protecting and enhancing the environment for future generations.
Following an exhaustive consultation process which included CABE Design Review and successful public inquiry, the 2010 Transport & Works Act consent (and three further planning consents in 2012) defined key qualities of the approved design, including the distinctive three-tower cable-stay bridge with its unique lower central tower. The approved plans were prepared by MGCB and its team of advisers (Ramboll with CH2M and Knight Architects) and the key visual qualities were set out in the requirements with which all tendering contractor teams had to demonstrate compliance through the tender period.
A competitive dialogue tender process was used and this successfully achieved financial close and award of the contract the end of March 2014. The winning team, the Merseylink Consortium, comprised the Construction Joint-Venture (FCC, Samsung, Kier) and the Design Joint-Venture of COWI, Fhecor, URS and Eptisa, with Dissing+Weitling as the consultant architect, responsible for developing the contractor’s design in accordance with the project architectural vision.
The centre piece of the new 6-lane highway crossing is the 1022m-long, multi-span cable-stayed bridge, spanning the Mersey Estuary and the adjacent Manchester Ship Canal. The unique design comprises three singular pylons which vary in height, with the outer pylons being 125m and 110m above river bed level, balanced by a shorter, central 80m tower. The clear spans between the towers vary between 294m and 318m, whereas their side spans reach out up to 205m, and the concrete deck is carried from a central cable plane. The unusual approach of using three pylons instead of the classic paired configuration, results from height restrictions prescribed by the nearby John Lennon Airport and limited locations where supports could be placed in the sensitive tidal estuarine environment.
The result is unusual not only in terms of its structural solution but also in its visual appearance, becoming a recognisable landmark structure which will be emblematic for its location and will define the skyline east of the Mersey estuary between Widnes and Runcorn for decades to come.
Martin Knight, Director at Knight Architects, said: “Mersey Gateway is a vitally important infrastructure project for the north-west as well as providing a distinctive new landmark for the region. It is also a great example of a flexible model of delivery which demonstrates that good quality need not be expensive and aesthetics need not be sacrificed when the economic climate cools. Having been an influential part of this extraordinary project for more than a decade we are delighted to see it open to the public.”
Mersey Gateway opens to public/traffic on 14 October. Official opening is due to take place in 2018.