M4 Closures in Swindon and Wiltshire: How to Manage Roadworks and Diversions in 2026

Published on December 26, 2025

Motorists and travelers heading to or from Swindon, Wiltshire, and the surrounding areas in 2026 will face significant disruptions as the M4 motorway undergoes essential maintenance work. Starting January 2, sections of the M4 will be partially closed between Junction 5 (A4) and Junction 15 (A419/A346). These closures are set to continue intermittently throughout the year, with the motorway shutting down between 9 pm and 6 am daily until December 24, 2026. This major infrastructure project will affect both local traffic and long-distance travelers, particularly those using the M4 to access London, Bristol, and surrounding towns.

M4 Closure Details: When and Where to Expect Disruptions

The closures on the M4 will take place during overnight hours, between 9 pm and 6 am, to minimize the disruption to daytime travel. However, with the motorway being closed at multiple points, including the slip and link roads at Junctions 8, 9, 13, and 15, the closures will have a significant impact on travelers, especially those passing through Swindon, Slough, Windsor, Maidenhead, and areas of West Berkshire.

National Highways, the government body responsible for UK motorways, has confirmed that a series of diversions will be put in place to help direct traffic around the affected areas. These diversions will involve alternative routes such as the M25, A4, A33, A34, and several other major roads, as well as local roads like the A308(M) and B4192.

While these diversion routes are officially approved, traffic conditions may change depending on local circumstances, so drivers are advised to check live traffic updates before traveling.

Impact on Business and Leisure Travelers

The extended M4 closures could lead to significant disruptions for both business travelers and tourists planning to travel through the region. For business professionals heading to meetings or events in London, Bristol, or Slough, the diversion routes could add considerable time to their journeys, especially during peak hours. Additionally, logistics companies and commercial drivers who rely on the M4 to move goods across the country will need to plan ahead to account for delays caused by the diversions.

Tourists traveling to or from Wiltshire, Berkshire, or the Cotswolds may also find their routes disrupted, particularly if they are planning to visit major attractions like Windsor Castle, Bristol Zoo, or the charming towns in the Cotswolds. The diversions, while designed to minimize the impact, will likely cause delays, especially for those not familiar with the area.

Key Diversion Routes and Affected Areas

To help travelers navigate the closures, National Highways has outlined the official diversion routes that will be used during the maintenance work. The diversion routes include the following:

• M25
• A4, A33, A34
• A308(M)
• A322, A327, A329(M)
• A338, A339, A355, A404(M)
• A419, A3044, A3113, A3290, A4155, and B4192

Drivers should expect significant changes to their usual routes and allow extra time to reach their destinations, particularly for longer trips between London and Bristol or South Wales.

Tips for Travelers

To help you manage the disruptions caused by the M4 closures, here are some quick tips for a smoother journey:

1. Check Real-Time Traffic Updates: Before setting off, always check the National Highways website or use live traffic apps to get real-time updates about any changes to the diversion routes or new closures.
2. Travel During Off-Peak Hours: If possible, plan to travel outside of peak traffic hours, especially on busy days when congestion is likely to be heavier, such as weekends and during holiday periods.
3. Allow Extra Time: Expect delays due to the detours and diversions. It’s recommended to add at least 30-60 minutes to your estimated travel time, depending on your route and destination.
4. Use Public Transport for Shorter Journeys: For those traveling within Berkshire or Wiltshire, consider using local public transport or trains to bypass the motorway closures altogether.
5. Stay Informed About Roadworks: Follow local news and traffic updates for information on any unexpected closures or delays. The National Highways Customer Contact Centre is available for further assistance if needed.
6. Prepare for Longer Travel Times: Particularly during busy periods like the summer holidays or the Christmas period, be prepared for longer-than-usual travel times on diversion routes. It’s advisable to plan breaks or stops if necessary.

Longer-Term Infrastructure Improvements

While the M4 closures may cause short-term inconvenience, the long-term benefits will be significant. The maintenance work is essential to improve the flow of traffic and ensure the safety of the motorway for years to come. Once the project is completed, the M4 will be better equipped to handle the growing number of vehicles, contributing to improved travel times and a more efficient transport network across the region.

The work at the M4 Junctions and surrounding areas is part of ongoing infrastructure improvements aimed at supporting the economic growth of the region, facilitating smoother travel for both local residents and visitors, and promoting safer driving conditions for all road users.

Conclusion: Managing M4 Disruptions for a Smoother Travel Experience

The M4 closures in Swindon and Wiltshire will undoubtedly cause some disruption throughout 2026, but with careful planning and awareness of alternative routes, travelers can minimize the impact on their journeys. Whether you’re a business traveler on a tight schedule or a tourist exploring the charming towns of Berkshire and Wiltshire, planning ahead and staying informed is key to navigating these temporary closures. By using updated diversions and adjusting travel times, you can still make the most of your trip while construction work continues to improve the M4 for the future.

Disclaimer: The Attached Image in This Article is AI Generated