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A456 Heads of the Valley

Client: National Assembly for Wales

Contractors Designers: Capita Symonds

Form of Contract: Design & Build Lump Sum

Dates work carried out: 2002 - 2004

Value: £38,000,000

A Design and Build contract to improve a busy 6.2km section of the A465 Trunk Road between Nant-y-Bwch junction at Tredegar and Dowlais Top junction, widening from 3-lane single carriageway to dual 2-lane carriageway with hard strip. The work, primarily on-line, required significant live traffic management on this busy Trunk Road, ensuring disruption and noise disturbance to local residents nearby was minimised. Free flow of traffic using this strategic route was essential and the potential of delay to motorists was signed in advance on the network approaching the site.

Fourteen new structures were designed and built including single and multiplespan bridges, retaining walls and culverts. The design accounted specifically to facilitate the minimisation of traffic disruption. This was achieved by maximising the speed of construction and improving buildability. All structures were developed to a common design to produce a consistent “family” of structures, saving time and cost in design, installation, and future maintenance. Our designer, Capita Symonds, performed the detailed design of the scheme, on behalf of the JV.

An economical design for the road foundation balanced cut and fill eliminating disposal of surplus materials. Along the route the demolition of old structures was required, including an old roadside restaurant and redundant buildings. This required specialist skills from a local demolition contractor within our supply chain. Major utilities diversions including High-Pressure Gas services were required demanding extensive co-ordination with statutory authorities and other stakeholders.

The scheme was delivered having acquired all consents from adjoining Local Authorities for side road connections, and the Environment Agency for discharge of surface water in a sensitive area prone to flooding. Approaching the project in a partnering arrangement with all major parties swift issue resolution and open, cooperative working relationships were formed. Examining each stage of the design we placed emphasis on value engineering throughout, phasing works to gain maximum benefit from programming in agreement with the client and stakeholders.