As a very small example of the thought process that is probably now evident in the minds of 'the authorities', the Blackwall Tunnel (A102M) in East London is, I think, instructive.
At one time, a couple of years ago, the two Lanes of traffic through the northbound 'old bore' were supplemented during the morning rush hours by one lane of the southbound 'new bore'. Diverting gates and lane closure lights emphasised local custom and it was a system that worked pretty well, allowing almost half as much traffic again, to flow through the tunnel. Once the peak morning period was over, the lights changed and the southbound bore reverted to two lane for the rest of the day.
For a reason best known to himself, but most Londoners suspect it was part of his agenda to shutdown private traffic in London entirely, Ken Livingstone - the Mayor - suddenly stopped the morning contraflow scheme. It was said that this was 'for safety reasons'. Now most Londoners had been completely unaware of frequent - or indeed any contraflow related accidents. This added 40 minutes to the average transit through the tunnel, making it about an hour and a quarter or more, to travel a couple of miles and cross the river Thames.
When Boris Johnson was elected mayor, he commissioned a review of the Blackwall tunnel situation and found, to no-ones great surprise, that the effects on accidents was negligable, but the effect on congestion was unacceptable. So he ordered that the contraflow scheme be reinstated.
However ........... the HSE said, 'oh wait, if we start the contraflow and there is an accident after all this time not doing it, then it will be our fault. So we cannot agree to opening it.' And there it rests, a perfectly good system for reducing congestion cannot be used because, basically, nobody wants to take the responsibility for saying it can.
As I said, a bit off thread, but you can probably see where I was going with it.
Roger.