M4 Westbound Traffic
If you are heading west on the M4 — out of London past Heathrow, Reading and Swindon, then on past Bristol, over the Severn and through Newport, Cardiff and Swansea — this page covers your side of the motorway. Traffic on a motorway is rarely the same in both directions, and neither is the news.
Heading the other way? See M4 eastbound traffic »
Search all the latest M4 traffic news
Latest accident or incident on the M4 westbound
The most recent accident or incident on the M4 westbound that we are aware of.
M4 westbound between junctions J11 and J12: broken down vehicle
23:509 Oct 2026reported 6 min ago
- Location
- M4 westbound between junctions J11 and J12
- Direction
- Westbound
- Lanes closed
- There is one of three lanes closed. The hard shoulder and lane one are closed
- Reason
- Broken down vehicle
- Schedule
- 15:26 Fri 9 Oct 2026 → 04:36 Sat 10 Oct 2026
Latest active roadworks on the M4 westbound
Roadworks live on the M4 westbound right now.
M4 westbound Jct 11 entry slip road closure
23:499 Oct 2026reported 8 min ago
- Location
- M4 J11 westbound access
- Direction
- Westbound
- Lanes closed
- Carriageway closed
- Reason
- Maintenance work
- Schedule
- 20:54 Fri 9 Oct 2026 → 06:00 Sat 10 Oct 2026
Latest planned roadworks on the M4 westbound
The next planned roadworks scheduled on the M4 westbound.
M4 both directions Jct 15 to 22 - mobile lane closure
23:499 Oct 2026reported 8 min ago
- Location
- M4 eastbound between J18 and J17
- Direction
- Both directions
- Lanes closed
- Lane closures
- Reason
- Maintenance work
- Schedule
- 20:00 Fri 9 Oct 2026 → 06:00 Sat 10 Oct 2026
Forecast - not confirmed
Search all the latest M4 traffic news
Updated 23:57 Fri 9 Oct 2026
Powered by National Highways’ Transport Data Feeds.
Check the M4 before you set off
Everything currently reported on the M4, both directions together, is on our latest M4 traffic news page, updated through the day. You can also check M4 roadworks, M4 accidents and M4 closures tonight.
Where the M4 westbound goes
The main interchanges you pass, in the order you meet them westbound:
- J4b — the M25, the London orbital · M25 traffic
- J13 — Chieveley, for the A34 to Oxford and Southampton
- J19 — the M32 into Bristol city centre
- J20 — Almondsbury, for the M5 to the Midlands and the South West · M5 traffic
- J21 — the M48 and the old Severn crossing
- J29 — the A48(M) for Cardiff (east)
- J49 — Pont Abraham, where the M4 ends, for Llanelli and Ammanford
How busy is the M4?
The Department for Transport counted the M4 at 81 points in 2025. Its busiest point carried 156,491 vehicles a day, and the average across all of them was 90,328 — both directions together.
Traffic count figures on this page are from the Department for Transport road traffic statistics, 2025.