M40 J1 Denham Roundabout

Layout and signage

N/A   A412



A4020


    A40






  Central London
A40
Slough
(A412)
Uxbridge
(A4020)

Lane configuration

LanesLanesLanesLanesLanes

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

LanesLanesLanesLanesLanes

  • Lane 1 continues, with option to exit.
  • Lane 2 continues ahead.
  • Lane 3 continues ahead.

Other events

  • Signs Start of motorway regulations
  • Signs End of motorway regulations

In this section

What's new

Silver bullet

The Silvertown Tunnel is finally open for business. One question remains: what’s it for?

Skid Risk, Accident, Fog

For the first time, we can share pictures of the pioneering experiment that lit up the Worcestershire countryside with enormous signs 61 years ago.

All change

In July 2024, a new Government entered office with a very different set of priorities. What does it mean for a faltering roads programme?

Share this page

Have you seen...

The Heads of the Valleys

The A465 Heads of the Valleys Road is one of the most spectacular trunk roads in the UK, and building it required some of the most remarkable civil engineering. This is the story of how the road was built in the 1960s, and how it's being rebuilt today.

About this page

Published

Last updated