Client: Cambridge County Council
Sector: Bridges and Infrastructure
Status: Shortlisted competition
The Marks Barfield / Babtie design for the new bridge is an elegant, straightforward structure, strikingly modern and instantly recognisable, which acknowledges the short span across the River Cam and ingeniously uses the geometry of the form of the structure, rather than over-dramatic, unnecessary structural engineering.
The division of the cycle and pedestrian “lanes” as the bridge crosses the Cam has a distinct structural purpose as well as giving better physical separation at the critical river crossing zone. The structural design is derived from the two ribbon-form decks, which are gradually separated, horizontally and vertically, from the points of support on the banks, such that a vierendeel structure is created. The double curvature ribbon bridge provides a highly efficient spanning structure with minimum construction depth, and very significant lateral and torsional stiffness designed to completely avoid any possibility of lateral excitation from human footfall (i.e. the Millennium Bridge issue).
Either side of the main river span, a pair of discrete supports on each bank effectively anchors the ribbon, reducing the structure at mid-span and contributing to the minimalist design at this critical location. The bridge will be constructed entirely from stainless steel for improved sustainability and to minimise whole-life costing. For the deck we have chosen perforated, non-slip stainless steel grid panels. Lighting is provided by long life LED lamps embedded in the underside of the handrail and at the base of the uprights, where they are least likely to be damaged or vandalised.