Avon Bridge replacement

Avon Bridge replacement

Facts and figures

  • Client: Dorset County Council
  • Value: £950k
  • Duration: 66 weeks
  • Completion date: December 2006
  • The Avon Valley, including the River Avon, is both nationally and internationally recognised for the species and habitats that it supports

The bridge is situated on the River Avon Flood plain, between Bickton and Christchurch, northwest of Sopley, and is on a site designated; a special area of conservation; of special scientific interest; of nature conservation interest; a wetland of international importance; and candidate special protection area.

The Avon valley has the greatest range of habitats and diverse flora and fauna than any other chalk river in Britain. The valley includes one of the largest expanses of unimproved floodplain grassland in Britain, including extensive areas managed as hay meadow. The River Avon displays wide fluctuations in water level and parts of the valley are regularly flooded in winter.

Despite environmental constraints, Interserve completed the construction of the bridge in 18 weeks, exactly on schedule. Excellent planning and design of this early contractor involvement scheme led to the successful outcome of our first ECI project with a local authority (Dorset County Council). Our integrated team comprised Interserve as Principal Contractor; Dorset Engineering Consultancy that carried out the preliminary design and project management; and Tony Gee & Partners, who were the designers with Middlemarch providing environmental expertise.

The existing five-span structure was replaced with a 38-metre, five-span, composite steel beam/reinforced concrete bridge deck founded on 500mm Ø driven tubular piled abutments and columns. The installation of the bridge structure was achieved by using pre cast units to reduce the requirement for on-site concrete works, which could have contaminated the river.

Considered locally as a vital road link between the New Forest and north Bournemouth, the opening of the Avon Causeway Bridge took place in November 2006. Christchurch Mayor, Cllr David Fox assisted by Dorset County Council chairman, Cllr John Peake announced at the opening ceremony: "…for the relief of traffic in Christchurch, I declare this bridge open."

Achievements

  • Successful fast track solution - delivered on time and to budget with no reportable accidents, despite construction deferral due to over-wintering birds and salmon spawning, amongst other environmental considerations
  • Cost and time savings with enhanced safety in bridge demolition as a result of Value Engineering proposals
  • A Construction Environmental Management Plan was developed in conjunction with the Environmental Statement and Environmental Impact Assessment
  • Extensive liaison with English Nature, the Environment Agency, the Avon Valley Liaison Group, local authorities, our key suppliers and riparian owners ensured stakeholder consultation, commitment and Planning Consent
  • Advanced offsite mitigation works for protection of rare valvata macrostoma snail
  • No damage to plants from pollution/contamination from the site; no reported incidents of pollution or contamination of the river; no impact upon the birds’ nesting or the fish