Main cable replacement study
Last updated on 13 Sep 2010
Following the discovery of corrosion within the main cables of the Forth Road bridge, consulting engineers WA Fairhurst were appointed in September 2006 to examine possible options for the replacement or augmentation of the main cables.
Fairhurst were assisted by the Danish company Cowie Consult and the American company Amman and Whitney, both of whom have extensive international experience in cable supported bridges. Edinburgh consultant SIAS carried out traffic modeling and economic consultant Roger Tym & Partners assessed the economic impact of traffic restrictions on the bridge. The work was peer reviewed by consulting engineers Flint & Neill and Transport Scotland.
The consultant has now completed Interim Stage 2 of the study which, through a process of review and concept development, has identified the most appropriate options for either replacement or augmentation of the main cables, should this become necessary.
The study also showed that replacement or augmentation, although technically feasible, would result in significant delays to the strategic road network over a period of 7-9 years if it had to be carried out without an alternative crossing in place.
The study concluded that major maintenance works on Forth Road Bridge over a sustained period, involving lane and carriageway closures, would potentially result in:
- economic output falling to a level in the order of £1 billion below that anticipated were the bridge to be operating normally
- a drop in turnover in excess of £1.3 billion below that anticipated were the bridge to be operating normally
- a loss of around 3,200 jobs, some of which may turn out to be permanent.
It should be noted that replacement or augmentation of the main cables will only become necessary if the current scheme to dehumidify the cables fails to prevent further loss of strength.
- Forth Road Bridge main cables: Replacement/augmentation study (Bridge Engineering, June 2010)
- Feasibility Study into the replacement or augmentation of the main cables of a long span suspension bridge (Fifth New York City Bridge Conference August 2009)
- Feasibility study for the replacement or augmentation of the main cables - Update and interim stage 2 report (21 February 2008)
- Feasibility study for the replacement or augmentation of the main cables - Preliminary findings (1 June 2007)
- Main cables - update report (1 December 2006)
- Feasibility study for the replacement or augmentation of the main cables - consultancy services tender report (24 August 2006)
Facts & Figures
- No restrictions on bridge (19:13 BST 26/09/14)