Skanska is the first in the UK to deliver a unique reinforced concrete encasement for V-shaped piers, to extend the life of an iconic bridge in Peterborough.
The works to strengthen six of the eight piers supporting the Nene Bridge, a 155m long structure carrying more than 60,000 vehicles daily, began in April 2018 and finished earlier this month – one month ahead of schedule. This major refurbishment was carried out on behalf of Peterborough City Council.
The project posed significant challenges including; its complex architectural design, no built-in solution for replacing the bearings, the limited headroom under the bridge deck, working in close proximity to a live railway line and two of the piers submerged in the river, making access difficult.
Skanska delivered the pier strengthening without compromising their distinctive shape, using several innovative techniques:
- The team used 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.
- Moving the heavy formwork panels from one pier to another with restricted headroom could mean a lengthy and expensive process of dismantling and rebuilding them. The team used an air skid system – 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, 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.”