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 M4 into London was one of the UK's earliest and most ambitious motorway projects. It was bold, pioneering... and almost instantly regretted.
An introduction to what I write, and why I write it, and where my strange new road sign simulator fits in to all this.
If you're on the motorway (in England at least) you might have noticed some funny blue signs down the side of the road. What are they for?
Buy me a coffee