The Forth Road Bridge will be reopened to all vehicles except HGVs from 6am Wednesday morning.
Operating company Amey confirmed that temporary repairs had been completed.
But Amey said that tests on the movement of the bridge’s joints showed “movement in the pin located at the lower section of the truss end link” is not sufficient to support HGV traffic.
The bridge has been closed since December 4 after a crack was found in a truss under the carriageway, causing major traffic chaos in central Scotland and financial concerns for many businesses.
The bridge — which links the Edinburgh area to Fife and the north of Scotland — will be reopened to more than 90 per cent of the traffic that uses it.
However, independent engineering experts agree with Amey’s assessment that loading the bridge with HGVs could result in “stress to the truss end link.”
They agree it is best to exclude HGVs from using the bridge until permanent repairs have been done over the next six weeks.
The bridge should reopen to HGVs in mid-February. HGVs account for 32% of the weight on the bridge despite making up only 9% of its traffic.
“Better than expected weather conditions and round the clock work by our teams allowed us to progress with the detailed inspection, scaffolding construction and actual repairs quicker than originally anticipated,” said Chartered engineer Mark Arndt, Amey’s account director responsible for the bridge.
“While we are pleased to have finished ahead of schedule for non HGV traffic to use the bridge, we are very aware of the on-going inconvenience for HGVs not having access.
“Public safety has been at the heart of everything we’ve been doing and work will be progressing over the coming weeks on the additional strengthening works required to enable HGVs to start safely using the bridge.”
Transport minister Derek Mackay said that with a temporary solution in place, the remaining work to install long term repairs can be safely carried out without the need for a full bridge closure.
The long term repairs will be carried out with overnight lane restrictions on the bridge.
“For the complex and detailed interim repair to have been completed in this timeframe is a tribute to the highly skilled and dedicated staff who have worked 24/7 since December 3rd,” said Mackay.
“This has been an unprecedented challenge. We can’t lose sight of the fact that many people have been inconvenienced by the closure.
“While that is deeply regrettable, I would like to thank the transport operators who pulled out all of the stops to put on extra services.
“In fact, I am pleased to announce that ScotRail have decided to continue the additional 05:52 Fife train given the popularity of the service, for as long as demand is evident …
“Since closure of the bridge was put in place it has also undergone a thorough health check. A painstaking inspection has been carried out involving over 65 rope access inspectors and drone footage to identify any other defects.
“The inspection is 90% complete and no material defects have been identified. It will be concluded by early January and there is no reason to keep the bridge closed while this is completed.”