M25 Junction 15: the M4 by Heathrow
Junction 15 is where the M25 meets the M4, on the western edge of Heathrow Airport. It is a four-level interchange: every movement between the two motorways has its own link road, so traffic never has to stop.
Live traffic speed flow: M25 Junctions 14 to 16
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Where the roads go
Take the M4 west for Slough, Reading and Bristol, or east towards central London. For Heathrow, Terminals 2 and 3 are signed from the M4 at its Junction 4, and Terminals 4 and 5 from the M25 at Junction 14, the next junction anticlockwise. Clockwise, the next junction is Junction 16 for the M40.
One of the busiest places on Britain’s roads
When the Department for Transport counted every stretch of road in Great Britain in 2025, the three busiest were all on the M25 around Heathrow, and one of them is the stretch from Junction 15 to Junction 16. With airport traffic joining from both sides, a single lane closed here is felt quickly in both directions.
For news about the M4 itself, see our sister site M4 Traffic.
M25 Junction 15 at a glance
| Junction | M25 Junction 15 |
| Meets | the M4 (M4 Junction 4B) |
| Near | Heathrow Airport, Slough and West Drayton |
| Next junction clockwise | J16 (M40, Denham) |
| Next junction anticlockwise | J14 (Heathrow Terminals 4 and 5) |
| Traffic news for the M4 | M4 Traffic |
| Busiest stretches nearby | J13–J14, J14–Heathrow and J15–J16: the three busiest stretches of road in Great Britain (DfT, 2025) |
Live traffic news at M25 Junction 15
Live traffic news at M25 Junction 15
Incidents and roadworks between Junction 14 and Junction 16 that we are aware of.
M25 Clockwise Jct 14 to Jct 15 Lane 4,3,2 closure
02:543 Oct 2026reported 7 min ago
- Location
- M25 clockwise within J14
- Direction
- Clockwise
- Lanes closed
- Carriageway closed
- Reason
- Roadworks
- Schedule
- 22:00 Sat 3 Oct 2026 → 06:00 Sun 4 Oct 2026
Forecast - not confirmed
+ 4 more near Junction 15 - see all the M25 traffic news →
This is the news for Junction 15 only, not the whole M25. For the rest of the motorway see all the latest M25 traffic news, the overhead signs and the speed limits in force now.
Updated 03:02 Sat 3 Oct 2026