The opening of the Queensferry Crossing has been postponed from May until between mid-July and the end of August, economy secretary Keith Brown told MSPs today.
He told the rural economy and connectivity (REC) committee the planned end of May date was “not now safely achievable”, which was a “huge disappointment”.
The new setback follows the opening being put back last June from December to May because of strong winds hampering construction progress on the £1.35 billion bridge.
The minister said a latest problems included strong winds delaying the dismantling of the tower cranes.
Other work in the vicinity also has to be halted during the operation.
Mr Brown said the first of the three cranes had taken 65 days to take down rather than an expected 15 days.
He said health and safety must be the top priority, especially since the death of a worker last year.
However, he stressed the cost of the over-run would be borne by the contractors, with no extra cost to taxpayers.
The construction consortium is also liable to pay penalties if they breach the end of the contract date in mid-June.
Mr Brown had told MSPs yesterday that “adverse” weather had delayed the opening for a second time – despite extra time being added when it was last postponed.
The original delay came despite a year of contingency time being built into the five-year construction schedule for the Forth Road Bridge replacement.
Last June, Mr Brown assured MSPs that the Forth Crossing Building Constructors consortium (FCBC) had “built-in allowances for future weather based on the experience to date”.
However, FCBC board chair Sally Cox told the committee today there had been 175 per cent increase in time lost to bad weather in January than had been included in those allowances.
Mr Brown said: “There are only nine weeks to the end of May. Even with the best weather, this date is not now safely achievable”.
Today’s announcement came after Mr Brown considered overnight a report from officials following an update from FCBC to the Scottish Government’s Transport Scotland agency, which is in charge of the project.
This had been compiled by experts brought in from across the world, Mr Brown said.
A Transport Scotland spokesman said today: “The contractor has reported there have been fewer clear weather windows than expected, particularly in relation to wind.
“This has delayed weather-dependent activities, causing them to bunch together at the end of the programme to a much greater degree than was anticipated in May 2016.
“This means a lot of construction activity is underway simultaneously, and careful planning is required to ensure that this can be done safely, so that one activity does not impact on another.
“At this stage of the project, all remaining activities are vulnerable to weather conditions.
“For example, the tower cranes can only be removed in wind speeds of less than 25 mph, and when this is happening, it is not possible to safely work within a 50-metre radius of the crane.
“Other works are also affected. For example, work on cable stays is sensitive to wind, waterproofing the bridge deck is sensitive to rain and road surfacing is sensitive to both rain and low temperatures.”
Mr Brown said: “While its clearly very disappointing the new bridge won’t be ready ahead of the contractual completion date, I believe it is important to take the time to make sure the bridge is built in the safest possible circumstances to the highest possible standards.”