Further discussions between the Government and the Forth Estuary Transport Authority (FETA) will now need to take place to determine the most suitable way of dealing with the cost increase.
FETA has been funded directly by the Scottish Government since tolls were abolished earlier this year. A three-year settlement had been agreed based on the Forth Road Bridge’s long-term plan of major capital works.
The contract cost to replace the joints and strengthen the deck was estimated at £8.7M in June, but the tender sums that were returned varied between £12.4M and £18.5M. Likely winner Balfour Beatty bid £13.8M.
"We engaged an experienced firm of consulting engineers [Atkins] to estimate the cost of this job, but the disparity between their estimate and the actual bids demonstrates just how unpredictable the costs of carrying out maintenance works on large bridges without major disruption to traffic can be," said Forth Road Bridge chief engineer and bridgemaster Barry Colford
"The joints we’re replacing are the oldest and largest of their kind in Europe and to keep the traffic flowing during the works we’ve come up with an engineering solution that is a first for a major suspension bridge."
Colford has pushed for Balfour Beatty to be chosen as preferred bidder, ahead of extra funding being agreed so that bridge maintenance deadlines can be met. Other bidders included Nuttall and C Spencer.
However, cost savings or reallocation of funding will be required before the contract can be awarded.