Chris5156 wrote: ↑Sat Mar 07, 2020 17:54
Peter Freeman wrote: ↑Thu Mar 05, 2020 12:04
I'm not sure why the difference arises, but we'd do it [road tunneling] and you won't (and I'm not saying you should).
In part it's a question of whether you want to encourage more people to drive and whether your city could sustain that. London has a population density more than ten times that of Sydney ... * Sydney has ~400 people per square kilometre, ... a lower population density even than Los Angeles County, which is by anyone's standards sprawling and car-dependent.
So yes, you could make a case for building tunnelled motorways under London, like those built in Sydney, but ...
I don't think it's about the lack of will to dig tunnels; it's about how much motor traffic it's desirable to have in a city as old and as dense as London is.
Yes, all very true. But I'm not suggesting that London, or the UK generally, should build (many) NEW roads in tunnels. I do believe that it is the answer to some issues that currently seem to be in the too-hard basket.
A prime example is completing (or virtually completing) grade separation of the A406. This is not a decision "do I want to make a safe high capacity road around the north side of mid-suburban London". That decision was made about 70 years ago. The road's already there, and the job's almost done. I could be missing some detailed engineering snags, but Henly's Corner and Bounds Green both appear to have ample nearby space to make even cut-and-cover
tunnelling feasible. Hardly any property acquisition, just temporary major ground disturbance. It's really not hard.
But I say once again - AU would, and does, but UK doesn't, and won't.