Work to reopen section of M8 to cost up to £156 million as finish date revised

More questions about the long-term future for the M8 motorway will be raised by confirmation that repair works and the propping up of the Woodside Viaduct section of the M8 will cost up to £156 million and last until at least early 2026.

Transport Scotland say: “Ongoing design and construction works has revealed the extent and complexity of the measures required to temporarily prop the viaducts and return the M8 to full traffic capacity. This has resulted in revised estimated costs and timescale to be determined.”

The cost range for the project is now £126-£152 million. The temporary propping work is expected to be fully completed in early 2026. It added that it is working towards reopening the eastbound carriageway in summer 2025.

Transport Scotland’s director of major projects, Lawrence Shackman, said, “The M8 Woodside Viaducts are a vital element of Scotland’s motorway network, carrying 150,000 vehicles daily. Our principal contractor, Amey, has been delivering this highly complex work on behalf of Transport Scotland while ensuring this busy section of the M8 motorway remains open.

“The ongoing temporary propping works are challenging due to the varying ground conditions and site constraints, including the presence of a plethora of public utilities as well as the Glasgow subway underground tunnels. Once the structure is fully propped, lane restrictions on the M8 can be removed.

“The construction programme expects the eastbound viaduct lane restrictions to be removed in summer 2025, followed by the removal of the westbound viaduct lane restrictions in early 2026.”

Four lanes of the motorway in each direction have been narrowed to two over the 50-year-old viaduct since March 2021. Shutting the outer lanes was a safety precaution after it was found to be in a poorer than expected condition.

At the time, a spokesperson for Amey infrastructure specialists said: “Transport Scotland were fully aware from their regular inspection regimes that the viaducts required repairs and undertook testing, inspection and load assessment to allow the full scope of that work to be determined.

“The required repairs were found to be more immediate than originally anticipated and the decision was taken to restrict traffic on the structures to reduce loading until the installation of propping and the repairs could be completed.

“The structures have been inspected annually and to national standards.

“Additional inspections of the half-joints were undertaken on a quarterly basis since 2020 to determine the rate of change.”

Last year Transport Scotland stated that the temporary propping work - necessary before any remedial work is undertaken - would cost £81.6 million and be completed by later this year. Preparatory repair work had cost £29.6 million.