Strengthening rail bridge wingwalls for containment barriers

Windsor Branch Railway Bridge carries the busy M4 motorway over a mainline railway and two public footpaths. The route forms the main link from London to South Wales and the south west of England. Constructed in the early 1960s, the bridge consists of five simply supported skewed spans each comprising precast, prestressed concrete beams. The deck is divided longitudinally into two halves by a covered central reserve light-well. A risk assessment identified the bridge as requiring high containment barriers to protect the railway line below. Unfortunately, it was not possible to install these barriers without additional structural strengthening. This paper discusses the use of ground anchors to restrain the wing-walls and capping beams against the collision loads imparted on the structure by the high containment barriers.