24 April 2019
sponsored by Unibail-Rodamco-Westfield
Chiswick Park Footbridge - submitted by Expedition Engineering
The Chiswick Park footbridge's opening marks the completion of one of London’s prestigious long-term real estate developments. The bridge is a key addition that manages to speak to the quality of the park, to the users and the businesses based there, while balancing the practical needs of Network Rail and the local adopting authority, and their long-term maintenance responsibilities.
Designing and constructing a bridge that has so many stakeholders made it very challenging. But strong teamwork, a clear sense of purpose and some strongly committed individuals enabled this project to be realised.
For the public, the quality is noticeable, enhanced by the stripped-down nature of the bridge to just three visible materials, weathering steel, timber and stainless steel. The striving for zero maintenance from the outset was at the heart of every design decision and followed through to construction and the detailed specification and component details. They wanted to produce something particularly special that is a substantial addition to the public environment, yet affordable and maintainable.
A project of this nature is only possible when risks are properly understood and fairly apportioned and mitigated. Even with a design and build contract, the client team held onto key external risks that were disproportionate to the construction. The key programme risk of Network Rail possession was carefully headed off by the team through detailed planning, meticulous attention to detail, and finished with mature programming with assumptions that problems would occur (and they did) built in. Generally, a proactive and empathetic approach from LendLease ensured that approvals were gained along the way and that key stakeholders were kept on side throughout the final stages of design and construction. More standard risks such as ensuring the apparently complex geometrical form could be safely constructed to, and that the interfaces between packages were resolved were implemented through the significant use of off-site construction and full-scale mockups and testing.
Ultimately, the construction of the UK’s first network arch footbridge was a success. It was built around a curve, over road and railway, with bespoke surveying and control processes. It involves an innovative cable stressing sequence. The team absorbed numerous unforeseen events, building safely, and without aggrieving neighbours, park users, local residents or the nature reserve.