Route
Junction number
1
Markerpost
30 km
Name
Denham Roundabout
Type
Non-standard interchange
Terminus
Terminus at end of exit list
Other routes
A40, A412, A4020
Authority
Restricted turns
Full access
Services
No services
M40 J1 Denham Roundabout
Layout and signage
| N/A | A412 A4020 |
|
A40 |
Central London A40 Slough (A412) Uxbridge (A4020) |
Lane configuration
- Lane 1 exits and returns after the junction.
- Lane 2 continues ahead.
- Lane 3 continues ahead.
- Lane 1 continues, with option to exit.
- Lane 2 continues ahead.
- Lane 3 continues ahead.
Other events
Start of motorway regulations
End of motorway regulations
What's new
The monster seen from below
What might it have been like to stand in one spot and witness the arrival, and the uncertainty, of plans for an urban motorway in West London?
The road that made no sense
It was the UK's only single-carriageway motorway, and twenty years ago it ceased to exist. This is the story of the strange fascination it held, and of my place in history.
The forever bottleneck, part 2
The second part of the story, where we learn why exactly the M4 gets narrower on the final approach to Europe’s biggest city.
Have you seen...
Skelmersdale Link to M6
Bold plans and unrealised ideas for the New Town of Skelmersdale are set out with great ceremony and excitement in this book that marks the opening of a road that became the M58.
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