M4 Junction 4B: Thorney (M25)

Map of M4 Junction 4B: Thorney — M4 Junction 4B: Thorney. Map data © OpenStreetMap contributors. Map drawing © Corporate Ace Limited.

Junction 4B is where the M4 meets the M25, at the M25's Junction 15, close to Heathrow. It is motorway-to-motorway only. Thorney, Harmondsworth and Longford are the villages around it. Heathrow Terminal 5 is about a mile and a half south.

Hauliers, coach drivers and anyone changing between the M4 and the M25 pass through here without stopping. If your route uses the M25 round Heathrow, this page and the M25's own news are the place to start.

For the M25 itself, clockwise towards Kent or anticlockwise towards the M40, see our M25 Junction 15 page ↗ (opens in a new tab) on M25 Traffic.

Check this junction now: live M4 speed flow map · latest M4 traffic news · M4 serious incidents · M4 accidents

M4 Junction 4B Now: Accidents, Incidents and Roadworks

Live traffic news at M4 Junction 4B

Incidents and roadworks between Junction 3 and Junction 5 that we are aware of.

M4 Eastbound Jct 4B to M25 Clockwise and Anticlockwise Jct 15 exit slip road lane 1 closure

PlannedUpdateAnticlockwise Slip road closed

Time now: Wednesday, 21 October 2026, 21:29 (9:29pm)

21:28 (9:28pm)21 Oct 2026reported just now

Location: link road from M4 J4B eastbound to M25 J15
Direction: Anticlockwise
Lanes closed: Slip road closed
Reason: Repair work
Schedule: 22:00 (10pm) Wed 21 Oct 2026 → 05:30 (5:30am) Thu 22 Oct 2026

Forecast - not confirmed

🚧HA scheduled: 22:00 (10pm) Wed 21 Oct 2026 → 05:30 (5:30am) Thu 22 Oct 2026 starts in about 30 minutes · lasts ~7h 30m

+ 2 more near Junction 4B - see all the M4 traffic news →

This is the news for Junction 4B 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 21:29 (9:29pm) Wed 21 Oct 2026

Live Traffic Speeds at M4 Junction 4B

The speed strip below shows the M4 around this junction, both directions, from National Highways’ live data, checked every five minutes.

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60 mph +50–5930–4915–29under 15

closedM62connecting motorwayA6A road👈M1our site: tap for its map

services, on the side you can reach them

crashincidentqueueroadworksspeed limitspeed shown on the signsstop-startoverhead sign

reported by drivers, which can’t always be relied onconfirmed by National Highways

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Go to our live M4 traffic speed flow map ›

In an emergency call 999. To report a problem on a motorway, call National Highways on 0300 123 5000 (24 hours).

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.

All the latest M4 traffic news →Live M4 traffic speed flow map →

M4 J4B in Our Records

Incidents here, last 13 days11 collision, 0 breakdowns or obstructions

Typical time to clear–too few cleared incidents to say yet

Slowest daytime hour westbound08:00–09:00average 56 mph (typical 59 mph)

Slowest daytime hour eastbound08:00–09:00average 48 mph (typical 55 mph)

The one incident we recorded at J4B in the last 13 days was a collision. Westbound, traffic usually keeps close to its typical speed through the day; the slowest hour is 08:00. Eastbound, the slowest daytime hour is 08:00, about 7 mph below the typical speed.

Average speed by hour of day at J4B

our average, last 12 daysNational Highways’ typical speed

Westbound

Eastbound

Incidents per week at J4B

collisionsbreakdowns and obstructions* part week: we started recording during it

The latest 1 here

Tue 13 Oct, 15:30 (3:30pm) Overturned Vehicle ✓Reported by National Highways
M4 westbound entry slip at junction J4B
✓ Cleared after about 317 minutes (5.28 hours)

Built from our own records of National Highways’ live data for the M4 either side of J4B: speeds from 12 days of five-minute readings, incidents from the last 13 days (we started recording incidents on 09/10/2026). Each incident is counted once. Updated every five minutes.

Junction M4 J4B, Thorney
Roads at this junction M25
Nearest town Uxbridge, 3.5 miles north
Junction before J4A, Concorde Roundabout, about 1.9 miles in a straight line
Junction after J5, Langley Roundabout, about 2.2 miles in a straight line

Around M4 Junction 4B: Thorney: Towns and Places on the Map

Map of the area within about 5 miles of M4 Junction 4B: Thorney, showing the towns, villages, roads and places to visit — The area within about 5 miles of M4 Junction 4B. Map data © OpenStreetMap contributors. Map drawing © Corporate Ace Limited.

Places on the Map Near M4 Junction 4B
Place	What it is	From the junction
West Drayton	Railway station	About 1.5 miles north-east
Heathrow Terminal 5	Railway station	About 1.5 miles south
Uxbridge F.C.	Venue	About 2 miles north-east
Coppins	Historic house or castle	About 2.5 miles north
Stockley Country Park	Park or nature reserve	About 2.5 miles north-east
London Heathrow Airport	Airport	About 2.5 miles south-east
Ditton Park Manor	Historic house or castle	About 3 miles west
Hayes and Harlington	Railway station	About 3 miles east