A421 Great Barford Bypass Scheme, Cambridgeshire, United Kingdom

As road congestion increases, there are more and more small towns and villages across the UK benefiting from bypass schemes. One of these is the A421 Great Barford bypass scheme in Cambridgeshire.

The village is situated between Bedford and St Neots and had for years suffered from the increase in traffic in the area. The bypass was first requested over 20 years ago.

A public inquiry was held in January 2003 after the plans for the bypass were first submitted and this involved some minor replanning of the over-bridges for the road. The bypass scheme started construction in October 2004 and was opened on schedule in August 2006.

Protestors had threatened to derail the project in August 2005 through various disruptions but this was short-lived. The scheme cost an estimated £57.7m, with an original budget of £38m.

PROJECT

The A421 project involved the construction of 7.7km (4.8 miles) of dual carriageway across a previous greenfield site to the north of the village of Great Barford. The road now connects the Bedford Southern Bypass with the A1 at the Black Cat roundabout near Roxton in Bedfordshire.

The project also included the construction of three under-bridges and five over-bridges. The project involved the movement of over 750,000m³ within the site.

CONTRACTORS

The contract was awarded in April 2004 to Edmund Nuttall Ltd (part of the Royal BAM Group) and Capita Symonds (designer), a construction package that also included the building of the A428 Caxton Common to Hardwick Improvement (a £55m contract). The Highways Agency (client) administered the scheme on an Early Contractor Involvement (ECI) basis.

The ECI allowed Nuttall and Capita to make a significant contribution to the early design stages and thus save time later in the project during the detail design and project costing. Edmund Nuttall Ltd were contracted not only to carry out the civil engineering and construction but also to manage the SU diversions, implementation of Environmental Statements, land management and liaison with all of the stakeholders in the project.

CONSTRUCTION WORK

The over-bridges were initially going to be constructed as in situ concrete bridges. However, because of the planning inquiry and the timescale, this was changed so that the bridges were constructed from steel composite (Corten steel) and included precast concrete sections. PERI UK provided a lot of the precast formwork for the bridge piers.

The precast formwork (VARIO GT 24 wall panels 8.5m high and 2.44m wide) was manufactured at PERI's rugby facility with a Wisa-form phenolic faced ply formlining. It was finished to a high-standard F6 concrete finish with chamfered indentations and tie holes at intervals for fixing the panels to the stantions.

ENVIRONMENTAL MITIGATION MEASURES

Environmental considerations were a large part of the project from the early stages. Environmental work included: protection of a rare species of great crested newt, archaeological investigations on the Greenfield site, 20,000m of fencing to contain farm animals, badger set protection, small mammal underpasses under the road, water monitoring in conjunction with the Environment Agency and use of recycled materials (FSBM) for the pavement of the road, which also meant less material was required.