Stretch of M8 plagued by five-year works could be demolished

A stretch of the M8 in Glasgow could be demolished after roadworks caused disruption to millions of commuters over the last five years.

Temporary propping of the motorway at the Woodside Viaducts in Glasgow began in March 2021 after the bridges’ supports were found to be in worse condition than expected.

The viaduct carries around 150,000 vehicles a day, but lane closures and permanent works have caused massive disruption since they began.

The estimated cost of these initial works is as high as £152m.

The date for completing the temporary repair to the Woodside Viaduct has been pushed back again. Transport Scotland

Amey, undertaking work on behalf of Transport Scotland, said last year it was working to overcome “previously unknown challenges” at the site, along with ongoing work to control previously known risks.

It is understood that the works remain on track, with the eastbound carriageway to be completed this autumn and the westbound carriageway in the second half of 2027.

However, in a letter to Transport Scotland, a Glasgow City Council spokesperson said the option to remove the viaducts could be “consistent with the council’s position”.

Removing the works is anticipated to have a major detrimental impact on traffic and journey time reliability.

Part of the M8 would have to close, and all through‑traffic would be rerouted via the M74.

It is estimated to cost less than £125m and take between one and two years to complete.

The other two options are either to repair or replace the viaducts, which could cost more and take longer.

The option to replace the viaducts could cost between £200m and £500m and take up to four years.

To repair them, it could take up to three years and cost as much as £200m.

Transport Scotland said it is keen to hear the thoughts of the local communities and road users on the permanent solution for the project.

M8 Roadworks: Timeline of expected six-year delays

March 2021 – Ahead of planned refurbishment work, intrusive inspections of the supports were completed and found the viaduct crossheads to be in a much worse condition than anticipated, requiring the implementation of traffic management to reduce the load on the viaducts
February 2022 – Propping completion projected as November 2023
February 2023 – Propping completion projected as late 2024
May 2024 – Transport Scotland updated on the progress and the challenging picture that had emerged of the complex work area within which the Contractor was working. An estimated cost range of £126m-£152m and propping completion in early 2026 with the eastbound carriageway sooner in summer 2025 was published

November 2024 – Transport bosses tell STV News that the roadworks are the “biggest on their books” after three-and-a-half years of delays
August 2025 – As a result of previously identified risks and the discovery of a conflicting sewer, timescales have been revised to the second half of 2027 with the contractor working to open the eastbound carriageway in Autumn 2026.
May 2026 – A number of options, including removing the viaducts, are being considered.

What do the current works involve?

Inspections in 2020 found the condition of the motorway bridges’ supports to be worse than expected.

The works include strengthening the triangular crossheads, which support the viaducts at their western end, and the associated propping steelwork.

Since November 2024, progress on the temporary propping has slowed, with only two new props jacked.

Transport Scotland said both of those elements have been “more complicated than anticipated”.

They say the need to avoid loading the Subway tunnels has introduced an “unusual level of complexity” and has resulted in delays to propping both the viaducts.

An existing sewer, adjacent to the Subway tunnel at the western end of the viaducts, was found to be in a different location than expected.