Murphy carried out the design and re-construction of Sydney Road Bridge, a three-span concrete arch bridge carrying a traffic-signal-controlled single carriageway that spanned two freight lines and the CMP1 West Coast main lines from Crewe to Manchester Piccadilly.
The improvement scheme was to substantially increase highway capacity by replacing the structure with a wider bridge that would carry two-way traffic and a shared cycleway and footpath over the railway. In addition, a signal-controlled Toucan crossing would be installed, along with improved cycle path provision, along Sydney Road.
The project was constrained by the existing overhead line equipment (OLE) and the requirement to construct new abutments adjacent to the West Coast main line. Murphy developed a methodology that managed the transfer of OLE from old to new structures and used innovative precast hollow units to construct the abutments.
Innovative use of precast abutment cells and staged alterations to OLE reduced impact on West Coast main line services.
As the RRAP was 2.5 miles north of the bridge, the time-on-site availability of on-track plant would have been very limited. To maximise the effective use of the limited hours during key possessions, we therefore planned delivery based on the extensive use of road cranes for the removal of the OLE gantries, the installation of the scaffold bridge and the demolition of the concrete arches.
The design included the fitting of new OLE supports to the new structure. The existing gantries had to be removed in advance of demolition to permit new abutment piling to take place, so we designed temporary fixings to the existing structure that allowed full support and full line-speed running until the permanent support arms could be installed. The gantry removals were lifted by a crane standing on the existing bridge rather than a road-rail crane, which enabled the full possession to be used. The new bridge deck beams were installed in two phases, to allow the OLE support arms to be transferred from old to new structures.
A key innovation for this project was the development of a rapid form of abutment construction. Murphy engineers used large, hollow precast blocks of a type that we had developed on another project. The units, which were manufactured offsite by Shay Murtagh, had cast-in sleeves to allow linking reinforcement to be installed. The units were installed during Saturday ‘rules of the route’ possessions while reinforcement and infilling with C40 concrete were carried out during the week.
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