M40 Speed Limits Now
This page lists the temporary speed limits being applied on the M40 — limits set by the electronic signs and lower limits through roadworks. Where no temporary limit applies, the normal national limit is in force.
On the M40 right now: 0 speed restrictions in force.
Checked 03:37 Sat 26 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.
0 speed limits on this page
Source: National Highways’ Speed Managed Areas data, as at 03:37 Sat 26 Sept 2026. Speeds converted from km/h to mph. Powered by National Highways’ Transport Data Feeds.
Why the limit on the M40 changes
Most of the M40 runs at the national speed limit. A lower limit can be set to smooth traffic when it builds up, to protect people dealing with an incident, or to keep traffic slower through a coned-off stretch of roadworks.
A speed limit shown in a red ring on a gantry or roadside sign is mandatory. A roadworks limit is an enforced limit in the same way; it is listed here alongside the others rather than hidden.
Where variable limits are used on the M40
Active Traffic Management, with limits set from the gantries, is used on the approach to the M42 at the northern end of the M40. Elsewhere, temporary limits are set for incidents and roadworks as they arise.
Where a lower limit affects the most drivers
A temporary limit matters most where the most traffic passes it. On the M40 that is the London end: the Department for Transport counted 136,403 vehicles a day between the M25 and Beaconsfield in 2025, and 133,167 between Beaconsfield and High Wycombe. North of the Chilterns the busiest stretch is Junctions 14 to 15 at Warwick, with 113,433. The final stretch, Junction 16 into the M42, carried 96,672 vehicles a day.
Reading this page
- Each entry gives the location, the direction and the limit in mph.
- Entries from roadworks are marked, and you can filter them in or out.
- Limits change as conditions change; the list shows what was set when it was last refreshed.
For the text on the same signs, see M40 overhead signs. For the works behind a roadworks limit, see M40 roadworks.
Traffic count figures on this page are from the Department for Transport road traffic statistics, 2025.