so I guess most of the really hard work is over
It seems that the least reliable part (in terms of time-planning) of the process is connecting to power.
I guess that this is mostly governed by the need to tell the council a month in advance of any work - and the penalties faced if that work takes too long. The consequence seems to be that there is at least a month to wait for power, and if any delay is encountered, they'd prefer to fill the hole in & start a whole new month's delay, rather than continue into the next day.
All in the name of trying to reduce jams on the road