The Railway Complex is an amalgamation of five structures into an integrated whole. Despite differing design requirements, the result is a united finish which diminishes the scale of the structures and complements the environment. The crucial factors of economy and low maintenance dictated the choice of structural form and use of concrete. Close attention to detail and good workmanship resulted in a structure that challenges the opprobrium so often unfairly associated with the word 'concrete', and is testimony to concrete's positive contribution to the built environment.
The River Crossing scheme is the final component in a link between the A548 North Wales Coast Road and the A550 Trunk Road. The main feature of the scheme is Pont Sir y Fflink, the new cable-stayed crossing of the River Dee. Another important element is the carrying of the route across the main Chester-Holyhead railway line. In all, five separate structures were built. These include a railway-retaining wall, a railway bridge carrying the road over the railway, a cable bridge (a top-hat protection to buried 132kV cables), a piled raft supporting the embankment and limited soil movements, and a cable wall preventing the road embankment encroaching onto the buried cables.
Construction techniques had to suit the 'rule of the route' working for most of the construction period. Accordingly, free-standing reinforced- concrete cantilever abutments were chosen for the railway bridge, with the deck formed from standard precast prestressed inverted T-beams. To minimise maintenance, the beams were integrated with the abutments by an in-situ reinforced-concrete corner detail poured concurrently with the concrete topping to the beams.
The structural action is such that the beams are simply supported for their self-weight and the wet concrete but the final structure is a portal frame for loadings from embankment fill and traffic. A similar structure was chosen for the cable bridge but, since the falsework could be simply erected, with a totally in-situ structure.
OWNER Flintshire County Council
CONSULTING ENGINEER Gifford Graham and Partners
CONTRACTORS Norwest Holst Construction, Kier Construction, Campenon Bernard sge
PRECAST BEAMS Tarmac Precast Concrete
PILES amec Piling
FORMWORK R Betts Construction, Firwood
READY-MIXED CONCRETE Tilcon Concrete
CEMENT Castle Cement