In article , tim...
writes
If you think that they can link a new route into a current motorways by only
diverting traffic for a few weeks then you have never seen how they do this

They're doing it where I live.

IME they narrow the road where the connection is to be made for the full
term of the works. They do this because they need access to the new road
for construction vehicles - how else are they going to build it?

Haul roads. That's what they use here.

They have narrowed the A14, I accept, but that's because they're also
doing stuff along the existing verges.

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Clive D.W. Feather