Bridging over the Swansea to Fishguard railway with two landscaped tunnels is a crucial part of the scheme to create the 22km long Millennium Coastal Park out of a stretch of derelict industrial land.
Without the land forms moulding the park across the path of the tracks the project would be cut into three distinct parts by the mainline railway. The task for principal designer Arup was to work within a budget of between £3.5M to £4M, covering the maximum possible amount of railway and blending the contours of the landscape using the minimum amount of imported fill.
Agreement was reached with Railtrack within four months and initial ambitious ideas for the tunnels were scaled down to the final scheme which was for 100m and 35m long precast concrete covers. These were assembled without special closures of the line and had sufficiently long spans to allow their support piling to be installed clear of railway operations.
The project was delivered on time and within budget, saving 13% against the target cost.