Operating company Amey today confirmed that it has installed a steel splint to repair the cracked member and concluded detailed load testing of the bridge.

The bridge was closed to all traffic on 4 December after a crack was discovered in a truss under the carriageway.

Engineers had hoped to have it repaired and open to traffic again by 4 January. It is now planned to open to HGVs in mid-February.

Transport minister Derek Mackay praised the team involved in the repair for working around the clock to get the bridge reopened.

He said: “I am pleased that we are now able to reopen the bridge to 90 per cent of traffic, well ahead of schedule. Following rigorous testing and inspection of the temporary repair, experts have recommended the bridge is now ready to open to all traffic except HGVs. With the temporary solution now in place, the remaining work to install the long term repair can safely proceed without the need for a full closure. The 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. Since the closure was put in place, weather conditions have been mainly favourable and the team have been able to complete the repair work in good time.

“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.

“We have said all along our focus was on reopening the bridge as soon as possible and so today’s news is very welcome. However we understand that there will be considerable disappointment that the bridge will require to remain closed to HGVs for a few more weeks. While HGVs account for 9 per cent of overall traffic on the bridge, they represent 32 per cent of the weight the bridge carries. We therefore have no choice but to accept the recommendation of the engineers. However, we will now work with hauliers to discuss what operational support will be available to them during the period when they cannot access the bridge. Engineers predict that following the permanent repair at the failed north east tower location, and subject to favourable weather and no further defects being identified, the bridge should reopen to HGVs by mid-February.

“In addition to the interim repair on the cracked member, splints are being installed on the other seven members as a precaution. Of these, work is already complete at four and the remaining three will be completed, subject to weather, by the end of December. There is no reason for the bridge to remain closed while this work is completed. The other seven members have also been inspected and load tested and no issues have been discovered. However strain gauges will also be attached to these members to gather accurate data on their performance.

“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 per cent 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.”

Work has been completed to repair the cracked member through the installation of a steel splint, as planned. As previously announced, this splint repair was always intended to be interim in order to allow the bridge to be safely re-open to traffic pending a permanent repair being carried out. Since completion of the interim repair, the member in question has been thoroughly load tested, monitored, and results gathered through the use of strain gauges. These sophisticated devices have been installed for the first time on the bridge and provide live and accurate data on strains, stresses and rotations within this area of the bridge.

The results from this monitoring show the bridge can now be safely reopened to all traffic, except HGVs and abnormal loads. This means that the bridge will be open to over 90 per cent of the traffic that uses it. Independent engineering experts have analysed the findings and agree with Amey’s assessment that loading the bridge with HGVs could result in stress to the truss end link. They agree the best way to mitigate against this risk is to exclude HGVs from using the bridge until the permanent repair is in place. This will take around six weeks to complete and, subject to favourable weather conditions and no further defects being identified, the bridge should reopen to HGVs in mid-February. Ministers and officials will now discuss with hauliers the operational support that can be offered to them during the period when they cannot access the bridge.

Chartered Engineer Mark Arndt, Amey’s account director responsible for the bridge, said: “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. 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.”