Tipner Bridge

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Year 3 Civil Engineering
A new combined foot, cycle and bus bridge connecting Tipner to Horsea Island at the Northern entrance to the city of Portsmouth
Group Members
Mark Kerri, Sally Pickard, Philip Steedman, Alex Terrasson, Jared Tiller

Dr. Joel Smethurst, Dr. Bloodworth

This bridge has been designed to link Horsea Island and Tipner located towards the northern entrance to the city of Portsmouth, to accommodate bus lanes, cyclists and pedestrians and act as a centre piece for the proposed redevelopment of the local area; including housing, job creation and the development of a new country park. The design is adjacent to the existing M275 motorway bridge and responds to a Site of Special Scientific Interest and a Ramsar wildlife protection zone. Examples of landmark bridges were researched and studied both for function and their structural form that enhanced the built and natural environment. Arch and cable-stayed concepts were developed with the cable stayed concept being progressed to full detailed design. The cable stayed bridge design spans 330m between piers with a 200m forestay supported by two lines of 10 cables and 6 pairs of backstay cables supporting 80 metres of deck. Computer modelling and hand calculations were used to design the relative stiffness of the pylon, deck and cables to minimise serviceable deflections and to ensure buildability. A unique feature of the design is the under-pylon which connects the deck to the main pylon. It transfers the compression in the deck caused by the cables, reduces the number of piers that are needed in the water and allowed a thinner deck to be designed. The longer time spent by cyclists and pedestrians crossing the bridge led to inclusion of a separate pedestrian/cyclist walkway. This is cantilevered from the main box girder which supports the traffic loading to enhance the experience of the user.

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