Garden Bridge at risk from Thames Tideway clash

The trustees of the planned Thames Garden Bridge are facing a race against time to complete the major works of the £175m project before early 2017 – if they don’t, they could be forced to abandon the project to avoid clashing with the development of Thames Tideway Tunnel.

Construction of the bridge could be put back by a decade, halted half-finished or scrapped entirely if the judicial review, which is due to be heard in the High Court by June, results in further delays to the construction timetable of the Thomas Heatherwick-designed bridge in central London, planning documents for the projects imply.

Most of the major works on the bridge – including closing the central river channel of the Thames to build the central span – need to be finished before the major work on the £4.2bn super-sewer begins in 2017, according to planning documents for both projects. Work was initially expected to start this year, according to reports, but has already been pushed back, in part due to the judicial review challenge, and is now due to begin January 2016.

Three contractors have been shortlisted for construction of the bridge – Bam Nuttall, Dragados and a Bouygues Travaux Publics/Cimolai joint venture.

According to the indicative construction timescale submitted as part of the Garden Bridge Trust’s planning application last year, the bridge will take approximately 35 months to construct (including seven months for mobilisation, establishment and contractor design).

The central closing span would be constructed 26 months after the project starts.

According to a Navigational Risk Assessment (NRA) compiled by risk consultants Marico Marine for the Garden Bridge Trust and its engineers Arup in May 2014, the bridge needs to reach this milestone before the vast amounts of spoil from the Thames Tideway Tunnel (TTT) are due to be taken down the river on barges up to 1km in length.

The planning submission by the Garden Bridge Trust states that: “Any other works involving restrictions to vessels would have been substantially completed by spring 2017, in advance of major river movement related to construction of the Thames Tideway Tunnel.”

In meeting notes from the NRA it was noted the bridge would “start in 2015” and the “bridge would hopefully be built before TTT is started”.

Spokesperson for the Port of London Marin Garside said: “The Thames Tideway Tunnel is a huge and complex major infrastructure project which will result in a significant increase in barge and other traffic movements through central London.  All works in the River connected with the bridge construction would need to be finished prior to the start of significant Tideway Tunnel traffic.”

Meanwhile, campaigners against Heatherwick’s Garden Bridge have been cleared to take the project to judicial review which will be heard before the end of June. The case has been brought by Michael Ball, former director of the local Waterloo Community Development Group, who served papers at the High Court in January.

Speaking about the potential delays, Garden Bridge Trust deputy chair Paul Morrell said: “It has been, and still is, the intention to complete construction by June 2018.

“The start on site to achieve that is January 2016, and we are in advanced discussions with contractors with a view to appointing one to meet that programme. However, there is indeed flexibility in this if necessary, and we would not expect constraints set by Thames Tideway’s programme to be critical to ours.”