Greek Street, Stockport. Rail bridge Reconstruction - FRC Package

Description

CMP2/1a Greek street carries the two lane Greek Street Roundabout over the five track electrified West Coast Main Line, in Stockport City Centre. Two Tracks run below the East Span with the three remaining tracks below the west span. The bridge was originally a tunnel but was reconstructed as an overbridge in 1958. The Two span Simply supported superstructure consists of precast post-tensioned prestressed concrete deck beams and in-situ reinforced concrete deck slabs. Gaps between the beams are formed by in-situ reinforced concrete. The intermediate support is provided by a reinforced concrete crosshead beam, columns and foundation slab. The deck beams are post-tensioned transversely. Parapets for the structure are comprised of brickwork. The bridge has a skew spans of 9.14m on the east and 13.99m on the west side, at angles of 13 degrees. The carriageway width varies from 9 to 13m due to the layout of the roundabout. Footways are provided adjacent to the north and south parapets of the structure, with varying widths. Trief Kerbing with a mounted pedestrian guardrail are present to separate pedestrians from the carriageway. Greek Street Bridge is a two span post tensioned structure in which the latest PTSI assessment concluded that the structure is understrength and overstressed. Engineering standard NR/CIV/025 has been used to manage the substandard structure in the short term with additional monitoring in place. Specific elements of concern included exposed concrete reinforcement which has begun to corrode on the deck soffit, seepage of water onto the soffit which will cause degradation to accelerate further. The most recent assessment report stated that the risk of failure was 'High' to 'Very High' and that deck replacement is required in 2025, otherwise the structure would need to be closed to road traffic until completely reconstructed, due to the overstress and deterioration it would not be safe to operate. The project proposal is to replace the existing bridge with a single span removing the central pier in a 21 day core possession in August 2025. This will require alterations to the existing OLE equipment that runs underneath the structure. The highway will also be closed for a significant period whilst construction works are undertaken to replace the bridge - circa 50 weeks. The deck construction works will commence once all beams are landed, connected and waterproofing membrane is installed. The sub-contractor will then be responsible for setting up all formwork and erecting steel re-inforcement (Opportunity to construct in cages may arise during design development, but please assume in-situ at this stage). Supply all associated concrete. Sub-contractor to then provide 2no. concrete pumps for duration of their pouring works. Sub-contractor to also finish concrete. Additional information: Relevant due diligence checks will be carried out. Construction Line RISQS SSIP Financial Checks