Route
Junction number
None
Markerpost
28.5 km
Name
Black Cat Roundabout
Type
Roundabout
Terminus
Terminus at top of exit list
Other routes
A1
Authority
Restricted turns
Full access
Services
No services
A421 Black Cat Roundabout
60mph speed limit begins
National Speed Limit beginsWhat'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...
Reigate Tunnel
An unassuming Surrey market town with an amazing claim to fame — the world's first road tunnel.
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