How Busy Is M4 Junction 8/9 to 10?
The M4 between Junction 8/9 at Maidenhead and Junction 10 at Winnersh crosses the Berkshire countryside east of Reading. In September 2026 this stretch was closed for most of a day after a serious collision.
In the Department for Transport’s 2025 traffic counts it carried 115,951 vehicles a day, making it the eleventh busiest of the 47 stretches between numbered junctions on the M4 that we could compare. This stretch has 4 count points; the figures here are from the busiest one.
Live traffic speed flow: M4 Junctions 7 to 11
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NOTE: The speed flow, overhead sign messages or other information shown on our live traffic speed flow map is updated every few minutes. We cross check the data and aim to provide warnings if there could be a delay or an inaccurate speed reading. There can be occasions, beyond our control, and despite our best efforts where the speed flow could be inaccurate. We cannot therefore guarantee the speed you can expect on any stretch of the motorway is always accurately shown. However we hope you will find our live traffic speed flow map a useful tool in trying to plan your journey. Safe driving.
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Latest M4 traffic news
Live traffic news at M4 Junctions 8 to 10
This is the news for Junctions 8 to 10 only, not the whole M4. For the rest of the motorway see all the latest M4 traffic news, the overhead signs and the speed limits in force now.
Updated 02:57 (2:57am) Sun 1 Nov 2026
For everything currently reported on the M4, see our latest M4 traffic news, M4 roadworks and M4 accidents.
The collision closure on 9 and 10 September 2026
At around 9.20pm on Wednesday 9 September 2026, a serious collision closed the M4 in both directions between Junction 8/9 and Junction 10. A police investigation kept this stretch shut overnight and through the Thursday morning rush hour. The eastbound carriageway reopened by about 2.25pm on Thursday 10 September, around 17 hours after it closed, and both directions were open again by about 4pm, around 19 hours after the collision.
Westbound traffic was diverted off at Junction 8/9 onto the A404(M) to Junction 9B, then along the A4 towards Reading, the A3290 and the A329(M), rejoining the M4 at Junction 10. Eastbound traffic followed the same route in reverse. With well over 100,000 vehicles a day normally using this stretch, a closure of that length affects a great many journeys, which is why we keep a record of it on our exceptional events on the M4 page.
Nine days later, the next stretch west was closed for a whole weekend: see M4 Junction 10 to 11.
Traffic on M4 Junction 8/9 to 10
115,951 vehicles a day works out at an average of about 4,831 an hour, or roughly 81 a minute, around the clock. That average takes in quiet nights as well as busy rush hours, so at peak times the flow is much heavier.
Split by direction, that count point measured 58,538 vehicles a day eastbound and 57,413 westbound.
Cars and taxis make up about 70% of the traffic. Vans account for around 19%, about 21,587 a day, and lorries for 12,031 a day, 10.4% of everything on the road.
The junctions at each end
Junction 8/9 (A404(M) and A308(M)) serves Maidenhead, High Wycombe and Marlow. Junction 10 (A329(M)) serves Wokingham, Bracknell and east Reading. Every junction on the motorway, with the service areas in between, is on our map of the M4 junctions, and the places to stop are listed on M4 services.
How it compares with the rest of the M4
The busiest stretches of the M4 are almost all at the London end, between Hayes and Slough, where airport, London and M25 traffic meet. The table shows the ten busiest.
| Rank | M4 stretch | Vehicles per day | Lorries |
|---|---|---|---|
| 1 | J4 to J4b | 156,491 | 6,249 |
| 2 | J4b to J5 | 140,828 | 8,712 |
| 3 | J5 to J6 | 138,753 | 8,436 |
| 4 | J3 to J4 | 136,321 | 5,243 |
| 5 | J19 to J20 | 128,594 | 11,167 |
| 6 | J6 to J7 | 127,570 | 7,577 |
| 7 | J7 to J8/9 | 126,197 | 7,861 |
| 8 | J10 to J11 | 121,922 | 8,549 |
| 9 | J28 to J29 | 121,902 | 9,572 |
| 10 | J25 to J25a | 117,507 | 9,599 |
Traffic figures are annual average daily flows, both directions together, from the Department for Transport road traffic statistics for 2025. On the M4 many stretches are split into more than one count point; where a stretch has more than one, the busiest measured point is shown. The ranking covers 47 stretches between numbered junctions; slip roads, spurs and the complex junctions 41 to 43 are left out. Hourly and per-minute figures are simple averages across the whole day and night. Contains public sector information licensed under the Open Government Licence v3.0.