10 December 2020 · By Fran Williams. Photography by Tom McNally

The 55m-long crossing – the UK’s first stainless-steel road bridge – replaces a 250-year-old three-span stone arch bridge, destroyed by flooding five years ago

The crossing straddles the River Eamont at Pooley Bridge at the Lake District's north-eastern gate. It replaces the historic 18th-century stone arch Pooley Bridge, the village’s namesake, which was destroyed during Storm Desmond in December 2015. A temporary bridge has been in place since March 2016.

The original Grade II-listed structure, built in 1764, served as a ‘critical link’ for residents and tourists.

Having won the contract back in summer 2017, Knight Architects has had to work around the temporary bridge and develop its design in collaboration with Cumbria County Council, the local community and stakeholders including The Prince’s Foundation and the Environment Agency to develop a ‘contemporary design which respects the sensitive setting and robustly fulfils new design criteria for flooding’.

The crossing features a composite concrete infill within the arch to ‘provide additional strength and stiffness while the open spandrels maximise transparency along the river’. Side stainless-steel girders connect the concrete slab between them with shear studs.

Despite taking the form of a classic deck arch, the bridge’s structure is a tied arch. The architect explains that the horizontal component of the ‘arch compression is transferred to the deck through 7.5m-long hidden side spans to avoid transferring loads to a ground with low capacity’.

Its width changes from 7.8m at the main span ends to 9m at its centre.

The flagship project was funded by Cumbria County Council as part of its £120 million Infrastructure Recovery Programme, which has so far delivered more than 1,200 schemes following the devastation caused by the 2015 storm.

The project was tendered in early 2018 and main contractor Eric Wright Group was appointed from Cumbria County Council’s civils framework under a design and build contract. The detailed design was developed by Eric Wright Group together with Knight Architects and submitted to the Lake District National Park Authority in February 2019.

In the last five years, Knight Architects has also completed a 50m bridge across the River Avon in Bath – the first new bridge in the World Heritage city for more than 100 years – and has designed other bridges including the £600 million Mersey Gateway and the A55 Third Menai Crossing.

In construction: bridge being lifted into place

As vocational bridge designers, we are used to the responsibility of transforming the territory with our work, but when your design is taking the place of a bridge that was there for 250 years (therefore the whole life of the current community of Pooley Bridge), a bridge that gave name to the village, that was such a fundamental part of its identity, this responsibility increases greatly.

The bridge was designed following an intense and meaningful engagement with the community at the concept stage, with little precedent in the bridge industry, which was key for the design to look as it does. It was a challenging process, but the pride of the community on their new bridge, a bridge they helped to design, is truly rewarding.

The new bridge pays homage to its predecessor, but it also looks to the future, aspiring to be a fitting addition to the site thanks to its slenderness and transparency, which not only provides unhindered views but minimises obstruction to water flow in flood events.

We used a number of innovations to achieve this combination of classic appearance and transparency: It is innovative in the materials being used (stainless steel and high-strength concrete), in how the materials are combined creating an atypical composite structure, and in the very unconventional layout of this structure, with part of it hidden within the abutments to make it look like a traditional deck arch but without transferring horizontal reactions to the ground.

Héctor Beade-Pereda, head of design, Knight Architects

Cumbria County Council are absolutely delighted with the new bridge! It is a fitting testament to the collaborative and innovative efforts of the entire project team, which included in-depth stakeholder engagement skilfully led by Knight Architects.

The elegant structure is deserving as an entrance to the Lake District National Park. Not only has the new bridge reconnected the Ullswater area after the destruction sown by Storm Desmond (2015) but it has reconnected the community and is an embodiment of the village and wider Cumbrian society - beautiful and resilient.

Pooley Bridge now has an iconic new crossing to be proud of and which will attract many visitors in the years to come.

David S Brown,  programme director, Cumbria County Council Infrastructure Recovery programme

Start on site June 2018 Completion date Opening October 2020, full completion January 2021 Deck area 508m2 Form of contract or procurement route NEC 3 (Tender for Concept Design + Stakeholder engagement); then Design and Build (with architects as concept guardians working for the client) Construction cost £5 million Construction cost per m2 £9,840 Architect Knight Architects Client Cumbria County Council Project management Mott MacDonald Design and build contractor Eric Wright Civil Engineering Concept design engineers Mott MacDonald Contractor’s consultant GHD Cat III checking Inertia Consulting Concept design independent checking K2 Ingeniería Environmental consultant PBA Ecology Stainless steel fabricator WEC Group / m-tec Stainless steel plate supplier Outokumpu Reinforced concrete works R Betts Construction Strand jacks / tensioning equipment Bill Boley Operated plant Waitings Stone paving and granite kerbs hardscape (installation: Helder Monteiro) Stone cladding Eden Stonework Bearings Ekspan Timber handrail Woodscape Lighting LTP integration Expansion joints Emseal Abutment flood doors Flood Control International Crane for bridge installation Sarens Temporary crossing Mabey CAD software used Rhinoceros

Tags Knight Architects lake district national park Pooley Bridge

Truly excellent – should gather awards aplenty. But the reference to ‘abutment flood doors’ in the credits (not obviously apparent in any of the images) made me wonder if the original 1764 bridge might still be intact if there’d been provision in past years of flood relief measures to reduce the risk of the river pressure by providing a channel or tunnel – which seems to have become fairly common practice around the country in the last few decades. Also, as an aside, the innovative use of some very heavy stainless steel plate welded to form the structure makes me wonder if hot rolled sections can be manufactured in stainless steel.

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