NEC-procured award-winning Tintagel footbridge reopens in Cornwall, UK

The spectacular Tintagel footbridge on the rugged Atlantic coastline of Cornwall, UK reopened to the public at the end of March. Successfully completed in August 2019, the NECprocured structure was subsequently closed for a total of seven months due to the Covid-19 pandemic.

Client English Heritage let the £5 million construction contract to American Bridge UK under an NEC3 Engineering and Construction Contract (ECC) Option A (priced contract with activity schedule) in October 2018. The new 68 m long, 2.4 m wide high-level crossing provides a far more accessible pedestrian link between the mainland and island parts of the thirteenth century Tintagel Castle ruins, avoiding a steep climb up from the existing low-level footbridge.

Twin cantilevers

The competition-winning arch-shaped design by Ney and Partners from Belgium and William Matthews Associates from the UK is actually two similar length steel-truss cantilevers with a 40 mm pinned gap at mid-span.

Weathering steel was considered for upper and lower hollow truss chords, but a 12 month site study indicated this would not develop a protective coating fast enough to ensure the required 120 year service life. Painted steel was therefore used, with duplex stainless steel finger joints, abutment pins, diagonal bracing and parapet bars.

Cable crane

Due to access, environmental and heritage restrictions, the 45 t main structure was erected in 14 prefabricated sections using a 4.5 t cable crane from France. These were progressively bolted together in situ, after which stainless steel trays filled with local slates stacked on edge were lifted into position to form the decking.

Groundworks included 14 post-tensioned anchors up to 17 m long for the upper reinforced- concrete tension abutments and four 5 m long mini-piles for the lower compression abutments. An adjacent cliff face was also stabilised with 24 anchor nails.

According to English Heritage, the Tintagel site now has the highest visitor experience score of all of English Heritage’s 300-plus historic sites. Awards won by the project include the Institution of Civil Engineers South West 2020 Showcase Award and a 2020 Structural Steel Design Award.