Planned Works on M8 Junctions 16 to 17 (Woodside Viaduct)

• Ahead of planned refurbishment work, inspections and intrusive investigations into the condition of the supports of each viaduct (crossheads) were undertaken in late 2020 and 2021 to help determine the extent of works. These investigations found that the condition of the concrete viaducts’ crossheads were in a much worse condition than anticipated. Temporary traffic management, lane closures and slip road restrictions, were installed on the motorway in March 2021 to reduce the traffic load on the viaducts.
• The work involves propping the viaducts to take load off the existing supports. Propping requires excavation to foundation level, avoidance or re-positioning of many services and installation of specially manufactured steel supports with jacks to remove load from the supports. In one location, due to services which can’t be moved, propping from foundation level is not possible and the deck is being propped via steel collars around the columns. At four locations around the SPT underground tunnels, which pass under the western end of the viaducts, special structures will be constructed to allow the deck to be propped and the load to be transferred to areas such that it doesn’t affect the tunnels.
• The first stage of the construction programme involving excavations, piling and other ground works around the existing viaduct columns commenced in August 2021. The installation of the props at the first location followed in February 2022. There are 23 locations that require propping.

To ensure the safety of road workers and the travelling public, speed and lane restrictions are in place on the M8 for the full length of both viaducts; the eastbound on-slip at Junction 17, westbound on-slip at Junction 15 and nearside off-slip at Junction 17 are closed. The slip road at Junction 16 remains open. Signed diversion routes are in operation.

Narrowed lanes have been introduced on the main carriageway of the M8 over the viaducts. HGVs are being encouraged to consider using an alternative route via the M74 where possible due to these narrow sections.

On the local road network, below the viaducts, the A804 Phoenix Road is closed. An alternative alignment of M8 junction 17 westbound on-slip has been created to allow Westbound traffic to access the M8 via West Graham Street.

There is currently no access to New City Road via Phoenix Road. A signed diversion is in place via Scott Street and Shamrock Street to New City Road. These restrictions are required to allow for essential excavation works to take place safely under the viaducts.
 

The traffic management on the M8 will be removed once all the required propping works have been completed.

The temporary propping works aim to minimise disruption as far as possible whilst keeping this stretch of the motorway open to the 150,000 vehicles that use it on a daily basis.

The temporary propping work is expected to be fully completed in early 2026. However, Amey is working towards delivering the eastbound carriageway sooner, in Summer 2025.

Amey will continue to explore opportunities to bring work forward where possible. These dates are subject to change due to unforeseen circumstances such as adverse weather or unexpected service diversions.

The work to undertake the temporary propping is extremely complex. Each of the 23 supports requires individual propping designs to take account of the varying column heights, span length and widths resulting in different loads to be supported by the props. The propping foundations at some locations are affected by a number of buried services and the SPT Subway tunnels beneath the viaducts, which has a major impact on the solutions available. The extent of the work required on each support is unknown until work gets underway.

Completion of the installation of the temporary propping is expected in early 2026, subject to any unforeseen events such as adverse weather or unexpected service diversions. However, the contractor is working towards delivering the eastbound carriageway sooner, in Summer 2025.

Transport Scotland is currently progressing a procurement competition to appoint technical advisors to develop the permanent works solution. Further information will be available in due course.

The cost of the temporary propping works is expected to be between £126m - £152m.

Work is ongoing to develop a procurement strategy for the permanent works. A cost estimate will be developed to inform the procurement process to appoint a Contractor. The cost will be refined once the construction contract has been awarded.

With the design progressing and detailed information being gathered to inform the construction of the permanent repair, the associated costs for propping and repairs will continue to be subject to change. Elements, such as the price of materials, will fluctuate due to external factors and changes in the market, which also influence overall costs.

During the morning (8:55am - 9:05am) and evening (4:55pm – 5:05pm) peak travel periods, eastbound delays of 6 to 10 minutes are common due to traffic volumes. Out with peak times, delays are generally 2 to 5 minutes.

During the morning (8:55am – 9:05am) and evening (4:55pm – 5:05pm) peak travel periods, westbound delays of 6 to 10 minutes are common due to traffic volumes. Out with peak times, delays are generally 2 to 5 minutes.

To ensure the safety of pedestrians and cyclists some footpaths may be subject to localised closures with temporary diversions provided. These diversions will be well signposted, with lighting provided on all diversion routes. Every effort will be made to ensure through routes for active travel are maintained during the project. However, cyclists are requested to observe ‘dismount’ signage where appropriate.

You can visit Amey’s website for more information or updates on the progress of the project.

The majority of construction work on the project takes place underneath the M8 carriageways which aren’t visible from the M8.
 

Please visit the Amey Southwest trunk road network website to report a problem on the network.

You can visit Amey's website for more information or updates on this project. A free Road Work Alerts service is available from the Amey website, an email address is all that is required to sign up for the service.