Truss End Links
Last updated on 3 Jul 2013
Following the assessment of the suspended span truss, these critical structural members were found to be significantly overstressed during certain combinations of loading.
However, given the cost and difficulty in replacing these elements, and the potential disruption to bridge users, further examination of the probability of certain combinations of load occurring and further structural analysis was carried out to try to determine the most realistic levels of stress in the members.
After the Forth Replacement Crossing opens, the existing bridge will carry only light traffic under normal operating conditions. One factor to be considered is the reduced probability of certain conditions of traffic loading occurring within the relatively short time period left until the new bridge opens.
As a result of this analysis work there is now the potential to upgrade the existing links rather than carry out a full replacement.
A repair option involving strengthening existing welds and adding stiffeners to the tower steelwork has been developed and a trial is being carried out on the south west tower leg. If successful, then this repair will be carried out on the other three tower legs.
The cost of carrying out the repair option to all the links, over years 2013 to 2015, is estimated to be £0.435 million. Strengthening the links will cost significantly less than full replacement which has an estimated cost of £10 million.
If the trial is not successful then the full replacement scheme would have to be reconsidered after the dissolution of the Authority in 2015.
Facts & Figures
- High winds - Speed restriction on bridge (04:36 BST 30/03/15)