HSE
I feel the need to start with the obvious: This is horrifying, and so close to a major disaster. One cannot imagine being inside the lorry that caught the brunt of the impact; the cab is heavily damaged, and clearly the driver was lucky to have had enough inertia to get the part he was in past the bridge before the full weight crushed through his cab. The motorcyclist's life, I daresay, flashed before his eyes. The idea of being in a car caught under debris, or a pedestrian feeling the bridge disappear from under you, is unimaginable.
The emergency response speaks for itself: They expected a major, mass-casualty disaster. They expected trapped victims and fatalities.
With all that said, I must ask where the Health and Safety Executive are in all this. Are they involved at all? I found them curiously absent from the sources.
Even if the bridge came down in a crash, the story does not end there. Was the bridge structurally sound? Was it built and maintained correctly? Was the design adequate? The answer to all of these, of course, is quite possibly; probably, even. It is not an absolute, however.
One does not watch 170 tons of bridge hit a busy motorway and just assume the bridge was fine. The police may well be best placed to lead a joint investigation, and I confess my knowledge is limited on how the arrangements for such things work. I would have thought, however, the specialism of the HSE ought to be represented in some capacity.
Come to think, it does strike an odd note, for me anyway, that HE is waiting for the result of the police investigation before deciding whether to do their own. I could maybe see them having some administrative reason for wanting the police conclusions to start them out on a right footing, but, yeah, it's hard to see how one could reasonably not ask careful questions about the thing. The sheer scope of what could have happened is appalling.