Description:

The Boyne Bridge is an asymmetric cable stayed bridge with an overall length of 352m traverses the River Boyne west of Drogheda. Cable stays, anchored in the head of the 95m high A-frame pylon, support the 170m main span at 10m centres. Counterbalancing cable stays tie the pylon head to the south abutment, which consists of a cellular reinforced concrete box with mass concrete fill.

The angle of inclination of the pylon legs, approximately 20 degrees, is one of the steepest ever to be specified and, as a result, has necessitated particular attention to construction methods. The 34.5m wide dual carriageway composite deck consists of a grillage of longitudinal and transverse steel girders supporting a reinforced concrete slab.

The four approach spans are supported by pairs of circular reinforced concrete columns of 2m in diameter. The deck steelwork is enclosed by a system of GRP panels, which provides protection against corrosion and access for inspections and maintenance. Extensive use is being made of Blast Furnace Slag Concrete, both for its aesthetic benefits and thermal characteristics.