Renovating The Tipner Interchange Bridges, Portsmouth

摘要

The Tipner Interchange bridges carry the M275 over Tipner Lane on the main approach to Portsmouth. Built in the 1970s, the bridges are owned by Portsmouth City Council and are due to become the responsibility of Colas, which manages and maintains the City Council's road infrastructure. In line with current practice, structures need to be of the highest standard at the time of transfer and the bridges were identified as requiring remedial work to combat concrete deterioration. This was evident by localised spalling of concrete cover to the steel reinforcement of all four of the piers that support the bridges.rnThe bridges comprise a three-span simply supported precast 'M' beam deck. Span lengths are 12.2m, 18.7m and 12.2m. The abutments are bankseats supported on an 'A' frame substructure with pile foundations. Intermediate piers are formed from reinforced concrete columns supported on pile foundations, with a crosshead at the top of the columns.rnConcrete materials, aggregate mix and form work management have of course improved greatly in the following years but the bridges have suffered from surface attack from rain, temperature fluctuations and atmospheric chemicals.