A new footbridge over the A27 near Chichester in the UK was officially opened at the start of November, and renamed the Whyke Horizon footbridge. It provides a safe crossing point over the A27 for walkers cyclists and residents, linking Chichester with communities, leisure facilities and walking routes south of the A27.
At the outset of design, rather than create an attention seeking landmark, design effort was placed on a more measured, respectful response to the context and design brief. The result is a subtle, low level structure, which together with earthwork ramps either side, helps the bridge to blend with the surrounding coastal landscape.
Regularly spaced transverse ribs, required to stiffen the through-trough, constantly change in profile across the span. This creates a cinematic experience as users walk or cycle across the bridge. Painting the interior an unexpectedly bright colour adds to this effect.
Through detailing and material selection, the sculpturally cloaked exterior gives way to a human scaled skeletal interior, providing a sense of discovery and delight.
Structurally, the 36 metre main span consists of an unusual steel hybrid box girder and half through-trough. This varying cross section evolved in response to both engineering and architectural objectives. The gradually changing structural depth is an expression of honesty and efficiency, providing greatest depth at midspan where it is needed for bending in the simply supported span. This characteristic also provides a sense of enclosure to bridge users as they pass over the busy highway before opening up to the desired views at the ends.
The main span of the bridge was lifted in overnight using a 350 tonne mobile crane, with the ramps and stairs on subsequent nights. The bridge was brought to site from Port Talbot, Wales in one 41m long piece. The main contractor for the bridge was Interserve Civils, with steel fabrication by Mabey Bridge and Afon Engineering.
