Tell us about the early design brief
Eton Dorney Lake was chosen to host the rowing and canoe sprint events for London 2012. Set in a 400 acre conservation area, the venue is a 2,200m, eight lane rowing course with a separate return lane that meets international standards. To meet Olympic standards we needed to enhance the existing infrastructure around the lake to create the best possible facilities for London 2012.
What inspired your design concept?
The geometry was chosen to complement the existing family of concrete bridges, but due to the increased span and width we found steel box girders to be a more economical alternative for the primary spanning structure. Narrowing from 12m wide at the end to 9m wide at mid span, the bridge gently curves both in plan and section, lightening and softening the visual impact. We also developed a raised 2.5m wide pedestrian walkway along the length of the bridge to provide pedestrians with a safe route and unobstructed views across the lake.
The primary bridge structure features two slender curved steel box girders which curve in plan and elevation and vary in height from 1.2 – 2.2m at mid-span and vary in width from 0.8m at mid-span to 1.2m at the ends. The box girders are interconnected with a series of steel plate cross beams at three metre centres which act compositely with the concrete deck.
What challenges did you face along the way?
The decision to hold the rowing and canoe events at the existing facilities at Eton Dorney Lake showed commitment by LOCOG and the Olympic Delivery Authority to providing the best possible facilities for the Olympics and avoid the complexity and cost of creating a new venue. However, in order to meet exacting Olympic standards, we needed to widen the entrance to the return lake to a minimum of 50m and provide an additional cut-through for the participants of the 500m races. Given these constraints, we carried out an options appraisal and assessed the enhancement works that would be required.
The enhancement works involved widening the entrance to the return lake and constructing a new 52m span finish line bridge for traffic at its entrance, then excavating a cut-through channel between the competition lake and the return lake and constructing a 21m span concrete bridge over this new channel. We also upgraded the existing access road.
How did it feel to be involved in such an important British project?
The enhancement work reinforces the world-class reputation of rowing at Eton Dorney. The work carried out brings the facilities up to the latest design standards for an international course and will help to keep the venue at the forefront of hosting international events and encourage grass roots participation.