12 February 2009
A review has concluded that replacement of Forth Road Bridge's expansion joints can safely be delayed until the new crossing opens in 2016, subject to conditions including a significant increase in inspection and monitoring. The review's findings are in a report that was presented yesterday to Scotland's Forth Estuary Transport Authority (FETA) by chief engineer and bridgemaster Barry Colford.
The joints are believed to be the oldest and largest of their kind in Europe and had been scheduled for replacement in 2010. FETA 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. Delaying replacement would allow the work to be carried out at greatly reduced cost and with minimum disruption to traffic.
FETA's own engineers worked together with Atkins to carry out the review. A section of the joints was opened up for inspection last month, providing an up-to-date benchmark of 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. 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 will be discussed by FETA's board when it meets on 20 February.