Design and Engineering

Designed by Ove Arup & Partners and built by Irishenco Ltd, West-Link is a pre-stressed concrete box girder bridge, consisting of five spans at a maximum height of 42m and an overall length of 385m. The bridge was dual carriageway in both directions. The 42m high pre-stressed concrete box girder forms a bridge in balanced cantilever construction.

The bridge has five spans, one 90m long, and the box is of a constant depth single cell. Piers are of a hollow concrete section. The deck was cantilevered out, using the balanced cantilever method from special sections at the top of each pier to near the middle of each span. Deck construction from each pier started off from an initial box section on top of the pier. This was called a pier table. The pier table was cast on formwork supported on a system of steel beams and was fixed to the pier until the deck from the adjacent piers joined together. The deck was constructed in segments using two sets of formwork travellers or carriages consisting of a shutter the shape of the concrete. The formwork was supported on an A-frame superstructure and a set of rails fixed to the deck allowed the equipment to move into position. Construction was completed and the bridge opened in March 1990.

Rising traffic volumes on the M50 required that the motorway have additional lane capacity added to it and as a result it was necessary to duplicate the existing bridge. The second bridge was completed in September 2003 and, is in effect, a duplicate of the initial bridge. At the same time the National Roads Authority purchased the bridge from NTR and while the bridge remains tolled the actual toll booths were removed and electronic tolling introduced. This has created a free flow movement on the motorway and eliminated the traffic restrictions imposed by the toll booths.