M4 closed between Harrow and Heathrow after police incident, diversions in place
The motorway shut at 1:35 am on 9 September 2026; National Highways reports no major delays and outlines westbound and eastbound detours
Trust 54Craft 77Hype 30How this was reported ▾
Official National Highways statement cited, but no named individual source.
How well corroborated and evidenced the reporting is. Higher is better.
Provides practical diversion details and specific data, but lacks quoted voices.
Context, balance and separation of fact from comment. Higher is better.
Mildly sensational headline, body remains factual.
How far presentation runs ahead of substance. Lower is better.
1 source assessed · methodology
National Highways announced that the M4 was closed in both directions between junction 3 at Harrow and junction 4 at Heathrow Airport at 1:35 am on 9 September 2026. The closure resulted from a police‑led incident, according to a statement posted on X by National Highways and reported by MyLondon. The agency added that, despite the shutdown, there were no significant delays recorded on the surrounding road network.
Background to the closure
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Police led the incident that forced the motorway closure, but the exact nature of the incident has not been disclosed by the force. National Highways confirmed the road remained closed in both directions for the duration of the incident. CCTV footage shared by MyLondon showed queues forming on the carriageway, although the agency’s traffic monitoring indicated that the queues did not translate into measurable delays for motorists.
Westbound diversion route
Drivers travelling west from Harrow are advised to follow a signed hollow‑diamond diversion. At junction 3 they should exit the M4 and take the third exit onto the A312 ‘The Parkway’. The route continues through three roundabouts for roughly four miles before reaching a fourth roundabout where the third exit leads onto the A312 ‘Church Road’. At the next roundabout motorists take the first exit onto the A40 westbound, which merges into the M40. From there they follow the M40 to junction 1a, keep left to join the M25 anticlockwise, travel to junction 15 and then take the right‑hand exit to re‑enter the M4 at junction 4b, continuing westbound.
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Eastbound diversion route
Eastbound traffic uses a hollow‑circle diversion. Motorists exit the M4 at junction 4, take the third exit onto the M4 spur towards London Heathrow, then at junction 4A take the first exit onto the A4. After about two miles they reach the Waggoners Roundabout and join the A312 north. Continuing on the A312 leads back to the Cranford Parkway interchange at junction 3, where the third exit returns drivers to the M4 eastbound.
Road closed due to a police led Incident.
National Highways, X post
Questions this report answers
+When was the M4 closed between Harrow and Heathrow?
The M4 was closed in both directions at 1:35 am on 9 September 2026. The closure covered the stretch between junction 3 at Harrow and junction 4 at Heathrow Airport and was caused by a police‑led incident.
+What diversion routes should drivers use?
Westbound traffic must follow the A312 ‘The Parkway’, then A312 ‘Church Road’, and the A40 to re‑join the M4 at junction 4b. Eastbound drivers exit at junction 4, take the M4 spur, then the A4 and A312 back to junction 3, where they re‑enter the M4.
+Did the closure cause major traffic delays?
National Highways reported that there were no significant delays despite the closure. CCTV images showed queues, but the agency’s traffic monitoring indicated that the queues did not result in measurable congestion for motorists.
+Who is responsible for the incident that closed the M4?
Police led the incident that prompted the motorway closure. The specific details of the police operation have not been released, but the closure was announced by National Highways and reported by MyLondon.
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