A12 J12 Marylands Interchange

Layout and signage

Billericay
A1023 (A129)
Mountnessing
Ingatestone
B1002
  B1002     A1023
(A128)
(A129)
  Brentwood
A1023
Kelvedon Hatch
(A128)

Lane configuration

LanesLanesLanesLanes

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

LanesLanesLanesLanesLanes

  • Lane 1 exits and does not return.
  • Lane 2 continues ahead.
  • Lane 3 continues ahead.

In this section

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.

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Mickleham Bends

Once it was one of the UK's most dangerous roads — just what is so special about a bit of dual carriageway in Surrey?

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