It is obvious that the diverted road is a long way from completion. The majority of it is still unformed and the bridge deck does not appear to have been surfaced. I wonder why they are closing the road now, rather than when the diversion is fully ready and just the connections with the old road have to be finalised? This reminds me of the rather cavalier way that HS2 handle road disruptiions with little regard for local road users. For example they closed a major road near me for about 9 months, causing untold inconvenience for users who had to divert many miles. Then they found that they could not complete the works they intended, so built a diversionary road which has now been in place for a couple or years. Why they didn't do that in the first place, I cannot understand. I think that maybe the local county council highways department let them get away with anything - regardless of the disruption to road users.
HS2 requirements trump local county council wishes. Agreed that the bridge section could have been completed before disturbing the old road. I guess they think they can surface the whole section in 1 operation.
There seems to be nobody there actually doing work of any significance. There"s more energy being used to operate all the unnecessary flashing lights than anything else. Know wonder these enormous projects take so long to complete, & always go massively over their original cost estimation.