Forth Road Bridge “truss end links”.

We know the Forth Road Bridge is closed due to a “north east tower truss end link” defect.  This is a pain for me as I live in Edinburgh, but my wife and I have family in Fife…. and Christmas is coming.

Like most people in Scotland I have crossed the bridge many times. I have also walked and cycled across it a few times.

As part of my job, I have been to the top of the bridge’s north tower, visited the anchor chambers and also walked on the truss under the truss deck (no problems spotted!).  These visits took place over the period where the tolls were scrapped by the SNP (meaning the Scot Gov had to fund maintenance directly), the main cable dehumidification (ground breaking stuff) and the privatisation of bridge maintenance by the Scottish Government.

All this means I know the bridge well, but I still don’t know what a truss end link is! However I do know that as bridge maintenance was publicly run lots of details are in the public domain. What did I find?

February 2009: It is recognised that work on the truss is needed, but this is (correctly) deferred until the main cable dehumidification is complete:
The assessment work has now been completed and an independent check is being commissioned. Strengthening work on the truss has also been put back until there is confirmation on the outcome of the de-humidification scheme. However, work on the truss end links is scheduled to start in 2010/11 following completion of the independent check

May 2010: A tender for work on the truss end links is cancelled.

October 2012: Audit Scotland say of Forth Road Bridge funding from the SNP Government: “The budget for capital expenditure was cut significantly and a report highlighting the impact on the Capital Plan was noted by Board Members.”

August 2013: Work on the truss is planned on the truss ends:
As reported in June 2013, the Chief Engineer and Bridgemaster will bring three projects to tender during 2013/14. The projects that have been selected on the basis of criticality and affordability are; Main Cable Acoustic Monitoring, Truss End Linkages and Suspended Span Gantry Improvements. It is currently estimated that these three projects will cost £2.270m based on the current Capital Plan. This will represent the majority of the funds available for non-committed schemes and therefore it is recommended that a full risk assessment of all projects on site is carried out before the tenders are approved.

February 2014: Planned work “deferred”  due to Scottish Government budget cuts: During this second round of deferrals, the four projects detailed below were identified as having the highest estimated cost.  Therefore, these projects had to be considered in part or full for deferral in order to produce a significant reduction in the predicted deficit.  These projects were:

1. The Upgrading of the Main Cable Acoustic Monitoring Project 
2. Improvements to the Suspended Span Underdeck Gantries
3. Truss End Linkages Work
4. Improvements to the Suspended Span Underdeck Access System

Later:
Upgrading of the Main Cable Acoustic Monitoring Project and the Truss End Links Project were both considered vital to maintain the operational capacity of the bridge and were *retained in the programme*.

and importantly:
There is always a residual risk when maintenance works are deferred and it was noted that deferral of part or all of these projects does increase the risk to the long term structural integrity of the bridge and is likely to increase the actual cost of the works when they are eventually carried out.  

May 2015: Work is further delayed: The intention of the Authority was to carry out a trial repair on one tower leg and if successful, this repair would be carried out on the other three tower legs. However, due to issues with the quality of the existing tower steelwork; the difficulties of access and the existence of red lead paint, coupled with the loss of key management staff, the focus changed during the year to completing the trial on one tower leg before the end of May 2015.  If the trial is successful, a recommendation would be made to Transport Scotland that this work be continued post abolition of the Authority. If the repair trial is unsuccessful then full replacement will have to be considered by Transport Scotland.