M4 J24 Coldra Interchange

Layout and signage

CANOLBARTH LLOEGR
The MIDLANDS
Trefynwy — Monmouth
A449 (M50) Link
Casnewydd — Newport
A48
  A48

A449
    A48

B4237
  Casnewydd (Dn)
Newport (E)
A48
Trefynwy — Monmouth
A449 Link

Lane configuration

LanesLanesLanesLanesLanes

  • Lane 1 exits and returns after the junction.
  • Lane 2 continues ahead.
  • Lane 3 continues ahead.

LanesLanesLanesLanesLanes

  • Lane 1 exits and returns after the junction.
  • Lane 2 continues ahead.
  • Lane 3 continues ahead.

Other events

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

In this section

What's new

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.

Hello, here's my ridiculous side project

An introduction to what I write, and why I write it, and where my strange new road sign simulator fits in to all this.

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Have you seen...

M1-A1 Link Road

Those last few miles of the M1 east of Leeds were completed in 1999. It looks for the most part like a fairly average piece of road, but one of the project's engineers describes some of the challenges that were faced.

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