M4 Junction Closures This Weekend?
Another significant motorway link connecting London and South Wales will be on the doorstep of disruption this weekend, August 29-31, 2025, when NH will implement junction-by-junction closures on part of the M4 because of an ongoing technical maintenance project.
When more than 130,000 vehicles ply this 189mile stretch each day, then delays due to these disruptions may affect travel across Berkshire, Swindon and South Gloucestershire.
Travellers are being asked to make advance preparations, pay attention to current diversions, and check real-time updates to minimise delays. This is what is happening with M4 closures, alternative directions and suggestions on how to cope as this busy weekend approaches.
Scheduled M4 Closures for August 29-31, 2025
National Highways has reported a number of restricted travel lanes around motorway 4 with works chiefly focused in the areas of road, repairing and maintaining the merging barriers, and fixing drainage systems, all of which will be taking place overnight to reduce inconvenience. On Friday, August 29, between 8:00 PM and 6:00 A.M., one in four lanes of the westbound M4 between M4, junctions 11 and 12 in West Berkshire will also be closed because of roadworks.
At the same time, there will be a closure of lane three in junctions 12 to 13 westbound to carry out similar works. The closures will be carried out to improve the road safety and quality of the surfaces, with planners putting diversions, which will be clearly signposted.
Between the same hours (9:00 PM to 6:00 AM), the M4 westbound at junctions 15 and 16 in Swindon will also be subject to lane two of three being closed due to roadworks. This is in continuation of the previous scheme, which starts August 29 and ends September 20, 2025, and takes up the same road at night.
As well as this, on the westbound entry slip junction 15, lane two will be closed, and this will affect access into Swindon. Traffic management: The occupants of the vehicles must observe slight delays and use local roads as diversions. On the M4, South Gloucestershire will deal with closures to the westbound lanes between junctions 17 and 18, with lane three closed between 8:00 PM and 6:00 AM due to the works on the roadside drain.
This is scheduled maintenance, which will occur nightly until September 20, 2025, as part of a multi-week plan. No complete closure of the carriageway is scheduled, in contrast to the major closures earlier in 2025 covering the demolition of the A432 Badminton Road Bridge, resulting in the closure of junctions 18 to 19.
Impact and Diversion Routes
Although no complete motorway closures are planned, lane restrictions may still lead to traffic congestion, particularly during rush hours. The M4 is quite a busy road, especially around Swindon and Reading and therefore, relatively minor closures can cause significant delays.
National Highways recommends following the diversions as noted rather than the use of satnavs, which are not likely to reflect real-time conditions on the road. As an illustration, westbound traffic will be diverted between junctions 11 and 12 by the use of local roads such as the A4 or A33, and it will be guided accordingly with clarity.
The closures along the Swindon (junctions 15-16) will see the traffic via the Oxford road or the A419, and maintain the access to the M4.
Junctions 17-18 South Gloucestershire diversions will make use of the A46 and A420 rather than entering the complex urban road network of Bristol. Motorists are advised to visit the Traffic England site of National Highways or local X updates to get live reports, as road closures may change with the weather or any unforeseen event.
How to Travel without Problems
To avoid weekend traffic, use navigation systems such as Waze or Google Maps to help you plot your route, since you may be forced to take longer than usual to get to rewarding destinations. The motorway technology in the form of a smart motorway with variable speed limits and emergency areas in Junctions 3-12 will control traffi,c but congestion is expected at work areas.
Use caution when travelling early morning, and be aware that any overnight roadwork may extend into 6:00 AM should there be overruns. On longer trips, try other routes such as the M40 or A34, but these could be subject to delays due to maintenance as well.
There are current projects such as the M4 junction 12 roundabout works that go on until the middle of March in 2026; therefore, it is important to be informed. For up-to-date information, visit nationalhighways.co.uk or m4traffic.co.uk. By being ready in advance to use road closures on August 29-31, the drivers can guarantee safer, more comfortable traffic along the M4 route.