What the M4 overhead signs are showing
This page shows what the M4 overhead signs are displaying right now — the electronic message signs National Highways use to warn drivers about closures, queues, hazards and journey times. They are listed junction by junction, in the direction of travel, for both carriageways.
Each message shows when National Highways last set it and how long ago. Signs can warn about a road ahead, so a message may be about a road you join later. We take road-closed messages off this page 12 hours, and other messages 2 hours, after National Highways last set them.
M4 overhead signs now
The speed limits showing on the overhead signals on the M4 right now. A number in a red ring is a mandatory limit; a number on its own is advisory.
On the M4 right now: 1 stretch with a speed limit showing on the signals (4 signals).
Checked 02:24 Mon 14 Sept 2026 These are the variable speed limits National Highways set on the overhead signals, usually for queues, incidents or roadworks.
Red ring = mandatory. A speed in a red ring is the legal limit. A number without the ring is an advisory speed. National Highways change these every few minutes, so we show when each was set.
⚠ Our last check of the speed signals was more than an hour ago, so we have hidden the speed limits until we check again.
1 speed limit on this page
M4 Westbound — 1 stretch on the signals
M4 westbound between J4 and J4B
02:1214 Sept 2026set 12 min ago✓ Checked by us 02:24
Speed Signals · 4 signals
Source: National Highways’ Speed Managed Areas data, as at 02:24 Mon 14 Sept 2026. Speeds converted from km/h to mph. Powered by National Highways’ Transport Data Feeds.
About the M4 overhead signs
The messages on this page come from National Highways’ own feed of the electronic signs above and beside the M4. We show them exactly as National Highways set them. A sign can be switched to a new message at any moment, so always follow the signs you can see on the road. For accidents, closures and roadworks see our Latest M4 Traffic News page.