Following destruction of the original stone Grade-II listed packhorse-bridge, the Pooley Bridge community was left divided. The unique replacement bridge, with its innovative stainless-steel structure, is both beautiful and able to cope better with flooding.
In total, around 80 tonnes of stainless steel was required, 2,000 tonnes of concrete laid and 650 square metres of locally sourced stone used. Over 250 people were involved in the project, working some 10,000 hours to construct the bridge.
Did you know …
The bridge work entailed some 80 tonnes of stainless steel, 2,000 tonnes of concrete and 650 square metres of locally sourced stone involving 250 people working for over 10,000 hours in total.
The beautiful slender new bridge was installed on site within the Lake District National Park, a UNESCO World Heritage site, in a single lifting operation that was completed in just three hours.
The UK’s first stainless steel road traffic bridge, Pooley Bridge, was built with unanimous community backing to replace a 250-year-old stone arch listed bridge that was washed away in a flood, leaving the community divided on either side of the river.
Measuring 128ft long, the landmark structure reconnects the Ullswater valley with a permanent bridge to replace the 18th Century stone structure destroyed during Storm Desmond in December 2015.
The bridge was a critical link to daily life. Its abrupt removal caused shock leaving the community separated, with a 15-mile detour to navigate in its place.
The need for a replacement bridge wasn’t in question. The design was. The desires of the community, the Lakeland-setting and its future uses all played an important role in determining the scope for the eventual structure.
A meaningful stakeholder engagement process took place, listening to the community’s views and focusing on their common aspirations for a design that fit both their sense of identity and location, whilst satisfying relevant technical standards.
A unique approach
The new bridge is unique and exceptionally slender with a 40-metre span open-spandrel arch design. It has an innovative stainless steel and concrete structure, designed to cope better with flooding and only requiring minimal maintenance.
The project required outstanding teamwork and meticulous planning to counter several challenges. The site itself was tricky, being situated on a mountainside with poor ground. In-river work had to be factored in, as well as the peak tourist season and salmon spawning times, all of which limited the available timeframe for work to take place.
The bridge is unique in terms of the materials used, and how they were combined to reduce its weight whilst retaining its strength and minimally obstructed views.
All sections of its design are bespoke, with a unique structural layout. The team used innovative solutions including adding sensors into the concrete to monitor the strength gain, a critical measurement in terms of planning the bridge lift. Steelwork was laser scanned after site assembly, but before installation, to make sure everything would fit perfectly.
To retain the architectural vision, a three-directional movement joint was developed specifically for this bridge with relevant accompanying analysis to prove its suitability for use. The bridge bearings were the biggest link-bearings that the supplier had ever designed or manufactured at 2.8 tonnes.
The transparent steel parapets permit the Lakeland views through the bridge and will minimise any obstruction to river floodwater. Duplex stainless-steel has many benefits for strength and requires minimal maintenance. It reduces the amount of concrete required, thereby reducing the bridge’s carbon footprint, and it is a 100% recyclable material. The 100%-recyclable material has excellent durability with little maintenance needed.
It has around 25% more structural capacity than a conventional steel which allowed for a lighter bridge both in terms of slenderness and weight, whilst still providing views of the landscape through the bridge and allowing for water to cross the structure.
Material choice was also based on whole-life-cost and was considered cost-effective and value for money when taking maintenance savings into account. The slender design minimised the amount of material used thereby reducing the associated embodied carbon content. The specific steel used has 1/5 of the embodied carbon of the global average of stainless-steel, due to using 85% recycled content and low-carbon energy at production sites.
A stunning result
The Pooley Bridge design and construction is an extraordinary example of the community, the landscape and the contractors working in harmony to provide an outstanding asset.
The replacement bridge was open for use on 23 October 2020 and is now attracting visitors to the area in its own right.
People who made it happen
- Cumbria County Council (Client)
- Eric Wright Civil Engineering (Contractor)
- Knight Architects, (Design)
- GHD (designer)
- Mott MacDonald (Client Project Management)
- WEC Group, R Betts, Sarens, Eden Stonework, PBA Ecology