Main Expansion Joints
Last updated on 13 Sep 2010
Current works on site:
Work is currently under way to install a permanent access system for inspection and to fit failsafe devices. No disruption to traffic or local residents is expected.
Raynesway Construction commenced work on the underdeck access platform in January 2010. Work is progressing well and completion is expected to be as programmed at the end of December 2010.
Installation of the failsafe devices and the replacement springs, bolts and other ancillary components is expected to be completed during the summer months by Forth Road Bridge's in-house maintenance team.
The main expansion joints allow the deck of the Forth Road Bridge to expand and contract as required by weather or weight of traffic. These joints are the oldest and largest of their kind in Europe, and had been scheduled for replacement in 2010.
However, the Bridge Authority ordered a review of the project following higher than expected tender costs and the Scottish Government’s announcement that a new Forth crossing will be in place by 2016. If replacement could be delayed until the new crossing opens it will allow the work to be carried out at greatly reduced cost and with minimum disruption to traffic.
The review concluded in February 2009 that the project can safely be delayed until 2016, so long as failsafe devices are installed and the condition of the joints is closely monitored.
FETA’s own engineering team worked together with consulting engineers Atkins to carry out the review. A section of the joints was opened up for inspection on the weekend of 16/17 January, providing an up-to-date benchmark of the components’ condition. The team then carried out a systematic analysis of possible failure modes and actions that could be taken to maintain current standards of operational safety and service. Consulting engineers Flint & Neill acted as peer reviewer.
The review team agreed that it would be possible to delay the replacement of the joints until 2016, subject to five conditions:
- Inspection and monitoring levels should be significantly increased
- A permanent access system should be installed as soon as practicable to aid inspection
- Key components such as pins and springs should be replaced and in some cases modified to improve performance
- Temporary failsafe devices should be installed as a precaution in case of failure
- Any decision to defer replacement should be reviewed annually or following any significant component failure.
The report's recommendations were approved by the Board at its meeting on 20 February 2009.
- Underdeck Access Platforms - Tender Award (30 October 2009)
- The maintenance of the main expansion joints on the Forth Road Bridge (Fifth New York City Bridge Conference August 2009)
- Main Expansion Joints Update (20 February 2009)
- Main Expansion Joints Replacement Tender (10 October 2008)
Facts & Figures
- The new Queensferry Crossing's towers have now reached half their final height: http://t.co/CjBgq2zmT4