Meeting of the Parliament 15 March 2016
I thank the minister for that helpful intervention.
As part of its inquiry, the committee was keen to establish whether the defect that led to the closure—a crack in part of the bridge mechanism that is known as the truss end link, which was subsequently found to have been caused by a seized pin—could have been identified earlier and the closure somehow prevented.
We were advised that, despite the fact that since 2001 there had been 23 inspections of the area of the bridge where the defect occurred, most recently in May 2015, no defects had been identified by engineers from the Forth Estuary Transport Authority—FETA—which was responsible for the maintenance and operation of the bridge up until June 2015.
The committee was advised that a key difficulty in finding the problem in question during an inspection was that the pin that was ultimately found to have seized, which led to the defect, would not have been visible, so there was no way of determining whether it was rotating properly. The former bridgemaster made it clear to the committee that, even with the robust inspection regime that FETA had in place at the time, FETA engineers did not foresee the issue with the pin sticking.
All the independent expert witnesses who appeared before the committee believed that everything reasonable had been done to inspect the truss end links and the pins on the Forth road bridge, but that the failure had been unforeseen and unforeseeable. The committee agrees with that view.
The committee heard how, following the identification of the defect and the closure of the bridge, temporary and permanent repair solutions were designed and implemented. The efforts made to deliver those engineering solutions, leading to the reopening of the bridge to the majority of traffic on 23 December, were considerable. However, the bridge could not be opened to heavy goods vehicles at that point, as further seized pins were identified, which necessitated a wider programme of repairs. The bridge was finally reopened to all traffic on 21 February this year.
The committee notes that the estimated costs of the full phase 1 to phase 3 programme of repairs are in the region of £19.7 million. Those costs are not insignificant, although they are clearly necessary to ensure that the structural integrity of the Forth road bridge is maintained.
The committee welcomes the fact that structural health monitoring equipment has now been installed on the Forth road bridge and notes that this will, in future, assist engineers in identifying stresses on bridge components.
A great deal of the discussion during the committee’s inquiry centred on proposals to replace the truss end links contained in FETA’s indicative capital plan, which was agreed in February 2010. The level of capital funding available to FETA was also discussed extensively, principally in the context of the impact that it may have had on its indicative capital plan proposals.
The indicative capital plan included proposals for carrying out work on the truss end links that had been developed following a report received by FETA in March 2008 from Fairhurst engineering consultants, which showed that the welds connecting the bracket at the top of the truss end links to the main towers were overstressed. The committee noted that the report contained no indication that either the links or the pins were found to be overstressed at that stage.
The estimated cost of the proposed works was put at somewhere between £10 million and £15 million, although it was noted that they had not, at that stage, been fully developed or designed. The committee is aware that FETA announced a tender exercise in May 2010 to identify consultants to provide advice on how the proposed work on the truss end links might be developed. That was withdrawn in March 2011.
It is not clear to the committee exactly why the tender exercise was cancelled in early 2011, although it notes that both former FETA and Transport Scotland officials have indicated that it was due to affordability issues. There is also at least a suggestion that it may have coincided with FETA beginning to explore alternative solutions to the replacement of the truss end links.
What was also not clear was whether the work on the truss end links, as originally proposed by FETA, had it been carried out, might have avoided the Forth road bridge closure in December 2015. Several witnesses told the committee that there was uncertainty over whether that proposal would have proceeded, given that consultants, if appointed, might well have proposed an entirely different approach.
However, what did clearly emerge was that following a challenging spending review in 2011, the capital grant allocation made to FETA by Transport Scotland was not sufficient to allow FETA to deliver all the non-committed capital works that were proposed in its indicative capital plan. As a result, FETA decided to carry out a risk-based reprioritisation of its indicative capital plan proposals. That resulted in the replacement of the truss end links coming fifth in the ranking against other priority projects. Engineers assessed that the failure of the truss end links would not jeopardise either the safety of bridge users or the long-term integrity of the bridge and the project was recategorised accordingly. On that basis, the FETA board agreed a recommendation that the truss end link project be deferred.
The committee’s view, from the evidence that it received, is that the development of the Forth replacement crossing would also have had an influence on FETA’s decisions to reprioritise certain capital projects.
In light of that, the committee, with the exception of one member, considers that FETA’s decision to defer the proposed work on the truss end links and subsequently to develop an alternative approach was an appropriate course of action, given the financial circumstances that the authority faced at the time, coupled with the engineering advice, which suggested that the project could be deferred.
The committee, with the same exception, is also content with the suggestion, which was made in evidence, that if any of the non-committed capital projects had been deemed to be of sufficient priority, FETA could have made an approach to Transport Scotland to request additional capital funding. Relevant precedents had been set.
In its report, the committee makes clear its view that FETA acted entirely professionally and responsibly in managing the maintenance of the Forth road bridge. The authority’s robust maintenance inspection regimes had identified that work was required on the truss end link mechanisms. FETA had developed proposals to take such work forward, which were reconfigured following the capital plan reprioritisation in 2011, and an alternative strengthening project was proposed. The alternative proposals were subsequently transferred to Transport Scotland and Amey and were taken forward in May 2015.
The committee commends all Transport Scotland, Amey and engineering consultant staff who were involved in responding to and resolving the defect, often in extremely challenging working conditions. The committee echoes the view of one of its expert witnesses, who referred to the response as a remarkable engineering achievement.
I look forward to hearing from other members during the debate, and I commend the Infrastructure and Capital Investment Committee’s report to the Parliament.
I move,
That the Parliament notes the Infrastructure and Capital Investment Committee’s 4th Report 2016 (Session 4), Inquiry into the circumstances surrounding the closure of the Forth Road Bridge (SP Paper 950).