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

Investigations into the condition of the supports of each viaduct (crossheads) were undertaken in late 2020, early 2021. These investigations found that the condition of the concrete crossheads was not as anticipated. Temporary traffic management, lane closures and slip road restrictions, were installed on the motorway in March 2021, following the completion of structural investigations. It was deemed essential to prop the suspended spans to allow more extensive repairs to be undertaken to the crossheads.

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 specially manufactured steel supports to be erected with jacks to remove load from the supports.    In some locations, due to services which can’t be moved, propping from foundation level is not possible and the deck will be propped via steel collars around the columns.  At four locations around the SPT underground tunnels, 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 the travelling public and road operatives, speed and lane restrictions are in place on the M8 for the full length of the structures; the eastbound on-slip road at Junction 17, and westbound on-slip at Junction 15 and Junction 17 off-slips are closed. Slip roads at Junctions 16 and 18 remain open. Signed diversion routes are in operation.

Narrowed lanes have been introduced on the mainline of the M8 over the structures. 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 structure, 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.

There is currently no access to New City Road via A804 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 viaduct.
 

Local road restrictions will be in place until the completion of the repair. The programme for the permanent repair works is currently being developed.

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.

*Please Note: Amey are exploring 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.

Each location requires bespoke propping solutions to reflect factors including differing geometry and heights, ground conditions and the extent and type of utilities. This has resulted in more complex design and construction work. 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 that all require careful consideration.

Once the propping work is completed the permanent repair work will follow. The programme for the permanent repair works is currently being developed. Further information will be shared once available.

The temporary propping works are complex in nature with bespoke design solutions being developed throughout. Delays to construction timings are always possible. Phases of the works may also be delayed or rescheduled if weather conditions are not favourable. Amey will continue to deliver this work safely, while minimising disruption to the travelling public and the local community as much as possible.

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 walkers and wheelers, 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, will request that cyclists observe ‘dismount’ signage where appropriate.

Enabling works including specialist excavations and ground investigation works are well underway beneath the viaducts. The first temporary propping system was installed in February 2022. It is particularly challenging to install temporary props at some locations due to existing gas, water and electricity mains threading beneath the viaducts.

Certain areas are also more difficult due to the proximity to SPT subway tunnels and utilities that cannot be diverted. The design required at these areas are complex and require a bespoke temporary propping system.  We are liaising with the relevant stakeholders to ensure we avoid any potential disruption to these services, whilst the viaduct works are ongoing.

While there may be periods when M8 road users may not see significant activity, a considerable amount of investigation, design and construction activities are ongoing below the viaducts.
 

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.