Route
Junction number
9
Markerpost
35.5 km
Name
Treborth Interchange
Type
Non-standard interchange
Terminus
Not a terminus
Other routes
A487
Authority
Restricted turns
Full access
Services
No services
A55 J9 Treborth Interchange
Layout and signage
|
Bangor Caernarfon A487 |
A487 | 
|
A487 |
Bangor Caernarfon A487 |
Lane configuration
- Lane 1 continues, with option to exit.
- Lane 2 terminates.
- Lane 1 has option to exit and splits to create a new lane.
Other events
50mph speed limit begins
National Speed Limit begins
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.
Have you seen...
Harry Yeadon
A civil engineer, working principally in the North West of England, responsible for many of the area's motorways.
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