M4 | Wiltshire | Carriageway Closure | Expect Delays

Incident timeline

1. 20:49, 18 JulFirst report

   The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 this evening.

2. 22:50, 18 JulUpdate

   The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 this evening.

3. 23:20, 18 JulUpdate

   ⏱ Still active — no changes from National Highways. Incident ongoing for 2h 30m. Monitoring continues.

4. 23:25, 18 JulUpdate

   The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 this evening.

5. 23:55, 18 JulUpdate

   ⏱ Still active — no changes from National Highways. Incident ongoing for 3h 5m. Monitoring continues.

6. 00:00, 19 JulUpdate

   The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 this evening.

7. 00:30, 19 JulUpdate

   ⏱ Still active — no changes from National Highways. Incident ongoing for 3h 40m. Monitoring continues.

8. 00:35, 19 JulUpdate

   The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 this evening.

9. 01:05, 19 JulUpdate

   ⏱ Still active — no changes from National Highways. Incident ongoing for 4h 15m. Monitoring continues.

10. 01:10, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 this evening.

11. 01:10, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 yesterday evening.

12. 01:40, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 4h 50m. Monitoring continues.

13. 01:45, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 yesterday evening.

14. 02:15, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 5h 25m. Monitoring continues.

15. 02:20, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 yesterday evening.

16. 02:50, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 6h 0m. Monitoring continues.

17. 02:55, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 yesterday evening.

18. 03:25, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 6h 35m. Monitoring continues.

19. 03:30, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 yesterday evening.

20. 04:00, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 7h 10m. Monitoring continues.

21. 04:05, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 yesterday evening.

22. 04:35, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 7h 45m. Monitoring continues.

23. 04:40, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 yesterday evening.

24. 05:10, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 8h 20m. Monitoring continues.

25. 05:15, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 yesterday evening.

26. 05:45, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 8h 55m. Monitoring continues.

27. 05:50, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 yesterday evening.

28. 06:20, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 9h 30m. Monitoring continues.

29. 06:25, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 yesterday evening.

30. 06:55, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 10h 5m. Monitoring continues.

31. 07:00, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 yesterday evening.

32. 07:00, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 on the 18.07.26

33. 07:35, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 10h 45m. Monitoring continues.

34. 07:40, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 on the 18.07.26

35. 08:10, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 11h 20m. Monitoring continues.

36. 08:15, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 on the 18.07.26

37. 08:45, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 11h 55m. Monitoring continues.

38. 08:50, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 on the 18.07.26

39. 09:20, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 12h 30m. Monitoring continues.

40. 09:25, 19 JulUpdate

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 on the 18.07.26

41. 09:55, 19 JulUpdate

    ⏱ Still active — no changes from National Highways. Incident ongoing for 13h 5m. Monitoring continues.

42. 09:55, 19 JulUpdate

    ✅ Incident cleared — M4 reopened at 09:55 on 19 Jul 2026. Total disruption: 13h 5m. All lanes open, traffic returning to normal.

43. 12:24, 6 NovFinal update

    The M4 westbound in Wiltshire is closed between J16 (near Swindon) and J17 (near Chippenham) following a serious collision that occurred approx. 20:05 on the 18.07.26

Wording from National Highways, recorded as it changed.

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