Harry Bloomfield, Esq. was thinking very hard :
Originally concrete slab, later tarmaced. They are resurfacing and have
scrapped up the tarmac down to concrete - how long do they normally leave it,
before returning to retarmac?

It's been two weeks now.

All done now, they finished it all off around 500 yards, during the
course of last week, at around 100 yards completed per day. Just the
speed bumps and yellow lines to be reinstated now. The only seemed to
work half days, mornings only. A massive double manned, tracked
machine, pushing a tipper lorry with the bulk of the hot tarmac on it.
Closely followed by a vibrating roller. So around six weeks, start to
surface finished.

The revealed concrete slab sub-surface had completely broken up in
several places, down to the soil - I'm surprised they didn't clean them
out and lay a new concrete sub-surface, before tarmac.