A404(M) Maidenhead Bypass

Maidenhead Bypass
Opened
Current route
A404(M)
Start point
M4 J8/9
Holyport
End point
9B
The Thicket
Original route
M4
Other numbers held
A423(M)

Part of a larger scheme, the rest of which remains M4.

Road scheme and chronology data is courtesy SABRE (where much of it was gathered by member Ross Spur), with additional data from the UK Motorway Archive, the Scottish Roads Archive and the Northern Ireland Roads Site.

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.

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Low Emission Zone

A first step towards emissions-based road pricing, a pointless measure to enforce something that's happening anyway, or another leap forward in traffic planning from the people who created the Congestion Charge? It's hard to say.

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