Repairs to the Forth Road Bridge are expected to start next week but its operator warned they would be weather dependent.
The firm said preparations were on schedule, with a platform being built to give welders access to the crack, 40ft below the southbound carriageway.
The crack is on one of the truss end links, which is part of the framework of girders which supports the carriageway.
Amey said detailed plans for the repair had been completed and verified by two independent specialist engineering firms.
It said the work would involve a “plate welded” repair to the damaged truss end link, and jacking the link into position.
The firm said it was also taking “preventative action” on seven similar locations on the bridge to avert similar damage.
Monitoring systems are being installed there too.
Mark Arndt, a chartered engineer who is Amey’s account director responsible for the bridge, said: “Our teams have been working 24/7 since the defect was identified a little over a week ago.
“Our design teams have finalised the detailed solution plan, the access platform is under construction and we’ve mobilised all the resources we need to begin the repair works.
“Progress of the repair work is vulnerable to weather conditions.
“Wind speeds at times make it unsafe for our people to continue, but by having our personnel on standby at the bridge and by monitoring live wind-speed data in our control room, we’re able to get straight back out to work on the repairs in every available window and our programme remains on schedule for completion in the New Year.”
The bridge was closed at midnight last Thursday night after the damage was spotted.
First Minister Nicola Sturgeon told MSPs today it was the “absolute intention” to re-open the bridge to all traffic in the New Year.
She said: “Any changes to the timescale will be fully communicated to the public.”