Transport for London and Sustrans approached Ramboll’s bridge engineers to investigate the feasibility of a pedestrian/cycle bridge upstream of Tower Bridge — the first proposed for this locale in decades. It's an ambitious project, designed to improve connections between Canary Wharf and the Rotherhithe peninsula in time for the London 2012 Olympics. We consulted a range of interested parties to assess multiple sites and viable options. Transport links, construction access, conservation, ground conditions and structural requirements were taken into consideration.
A suitable site was identified at Durands Wharf — it's close to housing, existing transport links and cycle networks, opposite open space at Westferry Road, and this position allows open sightlines for ease of river navigation. The Thames accommodates heavy traffic in this area, dictating the need for a high open-able bridge for the passage of large cruise ships, which pass here several times a day.
The steel and glass design that emerged from our detailed analysis is a single span, vertical lift bridge. The structure comprises two 80m towers that house the mechanism and deck balance counterweights. The towers — which incorporate a viewing platform — support a 180m main clear-span deck, providing 12-15m clearance for the majority of vessels and lifting to 50m above the water level for the passage of ships.
At each end of the deck, the approach ramps are configured in a helical design to facilitate a gradual 12m rise from shore to deck, allowing cyclists to remain in the saddle. The helical drums are located in the Thames channel to reduce construction costs, as local land is at a premium. Fixed spans connect the banks and approach ramps. With a total deck span of 190m, the proposed design creates the world’s longest, opening cycle and pedestrian bridge.