A55 J9 Treborth Interchange

Layout and signage

Bangor
Caernarfon
A487
  A487     A487   Bangor
Caernarfon
A487

Lane configuration

LanesLanesLanesLanes

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

LanesLanesLanes

  • Lane 1 has option to exit and splits to create a new lane.

Other events

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

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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London's Forgotten Arterial Roads

The 1920s and 30s saw a huge roadbuilding boom in London's suburbs. Some of those roads are incredibly well known, but here are five Arterial Roads that have been almost completely forgotten.

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