S30084 M60 Barton High Level Bridge - Bearing Adjustment - Cat 3 checks for the substructure AIP and GI survey reviews

Barton High Level Bridge (BHLB) is an eighteen-span steel-concrete composite structure carrying the M60 over the Manchester Ship Canal. The original bridge, constructed in 1960, comprised two independent deck halves formed from four longitudinal composite girders each, separated by a central reserve joint and supported by reinforced concrete bank seat abutments and hollow-column piers. The bridge was later widened between 1986 and 1989 as part of the M63 improvement works, with new edge girders and an extended deck slab added on both sides. Pre-widening investigations identified slight alkali-aggregate reactivity (AAR) in the original concrete, prompting a change in design approach. Instead of creating monolithic widened piers, the new outer supports were redesigned as independent, free-standing hollow reinforced-concrete columns founded on separate piles and connected to the original piers via link-and-pin "Pin Bearings". This configuration allowed independent vertical behaviour while constraining lateral and longitudinal movement, with the understanding that long-term monitoring and periodic bearing adjustments would be required to manage differential movements.