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 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...
Clear and legible
A century ago, one short memorandum issued by the Ministry of Transport laid the groundwork for a system of standardised, uniform road signs and a great deal more.
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