A woman in her thirties died on the westbound M4 between junctions 8/9 and 10 on Wednesday night. Thames Valley Police want dashcam footage from that stretch.

A woman in her thirties has died in a collision on the M4 east of Reading. Thames Valley Police are asking anyone who drove that stretch on Wednesday night to check their dashcams, and say there are people who were at the scene and have not yet spoken to them.

The M4 fatal collision happened at around 9pm on Wednesday 9 September, on the westbound carriageway between junction 8/9 and junction 10. Neither junction is in Reading borough. Junction 10 is the A329(M) interchange that serves Reading, Wokingham and Bracknell. Junction 8/9 is the Maidenhead turn-off, further east.

What the force has said

Thames Valley Police published its appeal at 2.31pm on Thursday 10 September. In its own words:

  • a white Mercedes 220 and a white Scania heavy goods vehicle collided on the westbound carriageway
  • shortly afterwards a second collision happened on the eastbound carriageway, involving a grey Kia Sorento
  • the driver of the Mercedes, a woman in her thirties, died at the scene
  • her next of kin have been informed
  • no arrests have been made

The investigating officer is Detective Sergeant Lyndsey Blackaby of the force’s Serious Collision Investigation Unit.

“Firstly, our thoughts are with the family and friends of the deceased at this extremely difficult time,” she said.

“We are appealing for anyone with information or witnesses who may have been at the scene and have not yet spoken to us, to please get in touch.

“I also ask any drivers who were in the area at the time and have dashcam footage to review it, as it may contain important information about the collision or the moments leading up to it.”

The force has not named the woman who died, and we will not speculate about her identity or about the cause of the collision. No one has been arrested.

How to send what you have

The reference number is 43260470931. Quote it on any contact.

  • Dashcam footage: upload it through the force’s SERIP portal page for this collision, which is set up for this collision.
  • Information or a witness account: call 101 or report it online.
  • Anonymously: Crimestoppers on 0800 555 111, or through the Crimestoppers website.

The appeal covers the whole stretch, in both directions. The second collision was on the eastbound side, so footage from drivers heading towards London is wanted as well as from drivers heading towards Reading and the west.

What it means for you

If you drove that section of the M4 on Wednesday evening, the useful window is wider than the moment of impact. The officer’s request is specifically for footage of “the moments leading up to” the collision, which is the part most drivers assume nobody wants. Cameras that loop typically overwrite within days, so if you have not already pulled the file off the card, it may not be there much longer.

These investigations are not quick. A death on the road is a matter for the coroner as well as the police, and nothing published by the force at this stage says why the collision happened.

For live conditions on the roads into and out of town, our Reading roadworks and travel page is updated with the current closures.

Questions people ask

Where exactly on the M4 did the collision happen?

On the westbound carriageway between junction 8/9, the Maidenhead exit, and junction 10, the A329(M) interchange for Reading, Wokingham and Bracknell. A second collision followed on the eastbound carriageway.

When did it happen?

Around 9pm on Wednesday 9 September 2026, according to Thames Valley Police.

Has anyone been arrested?

No. Thames Valley Police said in its appeal on 10 September that no arrests had been made at that time.

What reference number do I quote?

43260470931.

I have dashcam footage. What should I do with it?

Upload it through Thames Valley Police’s SERIP community portal, which has a page set up for this collision. Do not edit or trim the file first; the police ask for the footage as recorded.

Sources

Reported from the force’s own published statement. Court proceedings and the naming of private individuals are outside what we publish. Checked 13 September 2026.