Velindre
Wrexham
As part of the new Velindre Cancer Centre Hospital in Cardiff a new highway bridge was required to span over a disused railway line in the Long Wood Nature Reserve which is now in use as a footpath. The position of the abutments and span of the bridge was designed taking into consideration that the disused railway may re-operate, hence sufficient clearance had to be provided to remove the need for designing for impact loading on the abutments, equating to a 50m span and a midspan clearance of 15.5m. The new bridge is a single span skew arrangement with steel beams sitting on bearings and a bankseat. The Reinforced Earth bridge abutments had to fully support vertical and horizontal loads from the deck. What was especially challenging was that the skew with the disused railway line meant that there was a considerable cross-fall across the abutment faces hence a difference in wall heights in opposite corners. Where the wall was highest the soil reinforcing strips were longest, so to avoid too much temporary work support of the existing embankment, RECo optimised the design, also by using strips we were able to deviate the soil reinforcement to suit the complex geometrical constraints. As well as the bridge loads the Reinforced Earth structure has to resist the impact loads which would result from a vehicle collision on the H4a containment parapet on top of the walls.
Wrexham Industrial Estate is a strategic employment hub providing jobs for 7000 people and accommodating 200 businesses. It is one of the largest Industrial Estates in Wales and is a significant contributor to the local, regional, and national economy. The scheme involved the construction of 4km of new highway to provide a link from the North, an underbridge was required on the section where an access road connected to the existing Tarmac Quarry. The bridge would carry the Estate Access Road on a 14.7m span concrete beam deck cast integral with the bridge bankseats. This would be another in the growing list of references of Reinforced Earth abutments supporting such critical bridges where high loads are induced into the reinforced soil structure. The soil reinforcement chosen would be high adherence galvanised steel strips which are classed as ‘inextensible’ thereby reducing their long- term creep tendency compared to other soil reinforcing materials. Precast concrete facing panels were made with a vertical broken rib type pattern, a relatively inexpensive way to provide a high standard of textured finish.
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