A470 Abercynon Roundabout

Layout and signage

Aberpennar
Mountain Ash
Aberdâr
Aberdare
A4059
Ystrad Mynach A472
Aberfan (A4054)
  A4059     A4054
A472
A4054
  Ystrad Mynach A472
Aberfan (A4054)
Aberdâr
Aberdare
A4059

Lane configuration

LanesLanesLanesLanes

  • Lane 1 continues, with option to exit.
  • Lane 2 continues, with option to exit.

LanesLanesLanesLanes

  • Lane 1 continues, with option to exit.
  • Lane 2 continues, with option to exit.

Other events

  • Signs Traffic signals
  • Signs 50mph speed limit begins
  • Signs Traffic signals
  • Signs National Speed Limit begins

In this section

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.

Share this page

Have you seen...

Coventry Ring Road

The best ring road in the world? Possibly. The most frightening? Yes.

About this page

Published

Last updated