M4 crash J20–J21 westbound

Crash on the M4 westbound at J20–J21 on Saturday 31 October 2026, from 08:53. Cleared at 09:37 after 44 min. Timeline of reports from the motorway signs.

Status

Cleared 09:37 on 31 Oct 2026, after 44 min

Location

M4 westbound · J20–J21

Reported as

Collision

Sources

Motorway signs

Timeline

1. Sat 08:53 Motorway signs: “COLLISION SLOW DOWN”
2. Sat 09:37 Motorway signs no longer show “COLLISION SLOW DOWN”
3. Sat 09:37 All clear: no source reports it any more

Source reports

• Overhead signs read “COLLISION SLOW DOWN” (1 sign; furthest along: M4 westbound between J20 and J21).

Other recent incidents on the M4

• M4 crash J10–J8 eastboundyesterday 16:33 · cleared after 1 h 18 min
• M4 crash Eastboundyesterday 09:44 · cleared after 25 min
• M4 crash Westboundyesterday 08:29 · cleared after 40 min
• M4 crash Prince of Wales Bridge eastboundyesterday 08:13 · cleared after 22 min
• M4 stopped traffic J3–J2yesterday 06:48 · cleared after 2 h 13 min
• M4 crash J10–J11 westboundSun 05:12 · cleared after 1 h
• M4 crash J12–J11 eastboundSun 04:41 · cleared after 1 h 31 min
• M4 reported crash J17–J16 eastboundSat 17:47 · cleared after 37 min
• M4 reported crash J17 westboundSat 17:47 · cleared after 37 min
• M4 stopped traffic J3–J2Sat 09:48 · cleared after 25 min

Live traffic and past incidents at M4 J20 and M4 J21.

The sources don't report causes or injuries, so neither does this page. Times are UK time. For alerts, follow @motorways.me on Bluesky.