Route
Junction number
12
Markerpost
73 km
Name
Theale Interchange
Terminus
Not a terminus
Other routes
A4
Authority
Restricted turns
Full access
Services
No services
M4 J12 Theale Interchange
Layout and signage
|
Theale Reading (W) A4 |
A4 | 
|
A4 |
Theale Reading (W) A4 |
Lane configuration
- Lane 1 is gained from the entry sliproad.
- Lane 2 continues, with option to exit.
- Lane 3 continues ahead.
- Lane 4 continues ahead.
- Lane 1 exits and does not return.
- Lane 2 continues ahead.
- Lane 3 continues ahead.
- Lane 4 continues ahead.
Other events
Variable Speed Limits apply
National Speed Limit begins
What's new
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.
The forever bottleneck, part 1
The M4 into London was one of the UK's earliest and most ambitious motorway projects. It was bold, pioneering... and almost instantly regretted.
Have you seen...
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