Temporary and Permanent Works Piling - Successful Delivery of the Northern Spire Bridge, Sunderland

The paper describes the geology and ground conditions at the Northern Spire bridge site and detailed design of the pylon foundation piles, including 14.5m long, 25MN design load rock sockets. Details of the test pile construction, 60 MN axial load capacity O-cell test layout, location and instrumentation arrangement are also described. The highly innovative and unique bridge erection sequence required pre-assembly and horizontal launch of the bridge deck in two phases from the southern approach, using temporary pile supports in the river. The main bridge pylon was fabricated in Belgium and transported via barge to the site and then erected vertically to rest upon its substructure and foundations. Once this critical phase was completed, the bridge deck was launched through the A frame pylon structure and the deck was permanently connected to the pylon via 14 pairs of cable stays. The cofferdam was also designed to support a temporary working platform which allowed a 110 tonne rotary piling rig to install the bridge’s large diameter foundation piles from on top of the cofferdam, enabling a dramatic reduction in marine plant requirements. This platform provided a safer, higher quality methodology and delivered significant cost and programme savings on the piling works.