A major stretch of the M4 motorway in Wiltshire has reopened in phases after two serious crashes caused widespread disruption over the weekend.
The incidents led to overnight closures, emergency repairs and long diversion routes, leaving thousands of motorists affected.
Although traffic has started moving again, delays continue to impact commuters, with authorities warning that congestion could persist until all lanes are fully operational.
M4 Motorway Crash
The disruption followed two separate crashes on the westbound carriageway of the M4, both of which required immediate emergency response. The first incident involved a coach and a car, while the second crash occurred further along the route, compounding the situation.
Emergency services, including police, ambulance crews and highways officers, quickly reached both scenes. The seriousness of the incidents meant traffic had to be halted to allow rescue operations, investigations and recovery work to take place safely.
M4 Motorway Closure: What Happened?
Authorities closed the motorway after a major collision between Junction 14 (Hungerford) and Junction 15 (Swindon East) in the early hours of Sunday. The closure was necessary due to the severity of the crash and the need for a detailed investigation.
A second incident between Junctions 16 and 17 forced additional lane closures, creating a cascading effect on traffic flow. Together, the two crashes resulted in prolonged disruption across a significant section of the motorway.
M4 Motorway Diversion Routes
- Exit the M4 motorway at Junction 14 (Hungerford)
- At the roundabout, take the first exit onto the A338
- Continue on the A338 for approximately 3 miles
- At the A4 mini roundabout, turn right onto the A4 (towards Hungerford, avoiding the town centre)
- Proceed to the next roundabout and take the second exit into Charnham Park
- Turn right onto the B4192 and continue for around 13 miles, passing through Aldbourne
- At the A419 roundabout, take the first exit onto the A419
- Continue on the A419 and rejoin the M4 westbound at Junction 15 (Swindon East)
Motorists are advised to follow official diversion signs (hollow square symbol) and allow extra travel time due to congestion on these routes.
M4 Motorway Traffic Delays
The closures caused severe delays that extended well beyond the immediate crash zones. Traffic monitoring services reported queues stretching for miles, particularly during peak hours. The AA highlighted the extent of disruption, stating:
"Severe delays of 42 minutes and delays increasing on M4 Westbound between J16 A3102 Swindon Road (Swindon West) and J17 A350 (Chippenham). Average speed five mph." Commuters faced significantly longer travel times, with many choosing alternative routes or delaying journeys altogether.
M4 Motorway Crash: Which Roads are Open & Closed?
M4 Westbound (J14 Hungerford → J15 Swindon East):
- Partially reopened after earlier full closure
- Traffic is moving, but slow due to earlier repairs and congestion
M4 Westbound (J16 Swindon West → J17 Chippenham):
- One lane open
- Lanes 1 and 2 remain closed for recovery and investigation work
M4 Eastbound (all affected stretches):
- Largely open, with minor delays reported in some sections
Diversion Routes (via A338, A4, B4192, A419):
- Fully operational, but experiencing heavy traffic and congestion
Local Roads Near Diversions:
- Open, but slower movement due to redirected motorway traffic
- Motorists are advised to check live traffic updates before travelling and allow extra time for their journeys.
Serious Crash Between J14 and J15
The most serious incident involved a BMW and a National Express coach. Wiltshire Police confirmed the crash took place at around 02:35 BST. The driver of the BMW, a man in his 20s, sustained life-threatening injuries and was taken to the hospital.
Authorities have not reported any additional serious injuries, but the incident remains under investigation.
Coach Passengers Safely Evacuated
National Express confirmed that its 040 service travelling between London and Bristol was involved in the crash. "We can confirm the National Express 040 service between London and Bristol was involved in an incident.
"Emergency services quickly attended the scene, and passengers were safely transferred to an alternative vehicle to continue their journeys. "We are cooperating with the authorities and will provide any assistance to support their investigation."
Passengers were safely evacuated and assisted by emergency responders, ensuring minimal risk following the collision.
Oil & Diesel Spill Leads to Major Repair Work
The crash resulted in a large spill of oil and diesel, which significantly complicated recovery efforts. National Highways confirmed that the contamination required full resurfacing of the affected stretch.
"Due to the severity and seriousness of the collision, a complex and protracted collision investigation by Wiltshire Police was required, followed by vehicle recovery."
"This work was completed by 5.30 pm. The collision resulted in a substantial spillage of oil and diesel." Repair crews worked overnight to clean the road and restore safe driving conditions.
M4 Motorway Partially Reopens
Following extensive work, sections of the motorway have reopened to traffic. However, lane restrictions remain in place, meaning vehicles are still moving slowly through affected areas.
Officials have urged drivers to remain cautious, adhere to speed limits and follow instructions from road authorities.
When Will M4 Motorway Reopen Fully?
There is currently no confirmed timeline for full reopening. Authorities have indicated that the remaining lanes will reopen once all recovery and safety checks are completed.
Motorists are advised to monitor updates from traffic services and plan their journeys accordingly.
M4 Motorway Crash: Helpline Numbers
- Emergency Services (UK): Dial 999 - For immediate danger, serious injury or urgent assistance
- Police Non-Emergency: Dial 101 - To share information, including witness accounts or dash cam footage
- National Highways Customer Contact Centre: 0300 123 5000 - For live road updates and travel information
- National Highways Live Traffic Updates: Visit the official website or social media channels for real-time alerts
- National Express Customer Support: 03717 81 81 81 - For passengers affected by the coach service incident