The Nene Bridge (image courtesy of Skanska)
Skanska has claimed to be the first contractor in the UK to deliver a unique reinforced concrete encasement for V-shaped piers.
While working on a refurbishment of a bridge in Peterborough, the contractor strengthened six of the eight piers supporting the 155m-long Nene Bridge, which carries 60,000 vehicles a day.
The work for Peterborough City Council finished this month, one month ahead of schedule, having started in April 2018.
The challenging project involved a complex architectural design, no built-in solution for replacing the bearings and limited headroom under the bridge deck. It also required working close to a live railway line, while two of the piers are submerged in the river, making access difficult.
Skanska said it delivered the bridge strengthening without compromising the piers’ distinctive shape by using several innovative techniques including:
- Hundreds of steel bars to wrap each of the unique piers, creating complex reinforced concrete jackets that supplement the unique geometry of the structure.
- As two of the piers requiring strengthening were positioned within the River Nene, a temporary coffer dam was built to provide access below the water level.
- An air skid system to move the heavy formwork panels from one pier to another with restricted headroom, which involved placing air skid pads under the formwork and skating it into its new position on 2mm of air – to achieve time and cost savings of 90% and 70% respectively.
- The team also used digital tools throughout the project, creating 3D-printed models of the four stages of construction of the bridge piers; existing pier, pier following hydrodemolition, first concrete pour, and completed encasement to visualise the geometry of the complex, multifaceted structure.
Mark Shopland, Skanska operations director, said: “This was a technically challenging project that gave us a great opportunity to utilise our wide spectrum of expertise from across our construction and design teams, working collaboratively with our supply chain. We were also able to use the latest engineering technology to deliver an innovative solution to a significant challenge faced by our valued customer, all the while preserving the distinctive appearance of this iconic bridge for another 50 years without any road closures.”
Councillor Peter Hiller, Peterborough City Council’s cabinet member for growth, planning and economic development, said: “The bridge is a key part of the city’s road network, carrying a significant number of vehicles each day and it is imperative for it to be in good condition. This vital complex and extensive work was completed on time and without any disruption at all for motorists, which is a staggering feat of engineering. It will ensure the bridge can continue to be used for decades to come.”
