However, pedestrians can cross wherever/whenever they think that it's safe to do so anywhere in Britain (Northern Ireland I think has some kind of jaywalking law). It's not just in London or other cities, but remote countrysides too where crossings may not be available. Pedestrians have priority, but it's definitely frowned upon to cause vehicles to have to slow/swerve to avoid a collision.
The Highway Code was recently updated (a few years ago) to make it more explicit that pedestrians crossing a side road junction should have priority over vehicles trying to turn into the side road. However, that's not necessarily followed by all drivers/cyclists etc.
Basically, drivers/cyclists are expected to make all efforts to avoid a collision and will be considered at fault unless it's a scenario where the pedestrian steps into the road without enough time for the driver/cyclist to react and avoid them.
So on that basis, jaywalking should be prohibited on Manhattan Island, because it's population density is greater than that of London, which we have for some reason decided is the arbiter, but allowed virtually everywhere else in the US, where the population density is less than London?
If you allow pedestrians to cross anywhere at any time with right of way, that can work to a certain density. On the other end of the scale, traffic will be at a standstill due to a constant stream of pedestrians. I don't know exactly where on that scale either of those cities is, but the argument that it works in the UK where the density is 5x less seems flawed.
I've posted in the sibling thread r.e. the density (which I believe you have underestimated by several orders of magnitude), however a stroll around london will show you that, excepting arterial roads, cars always have to deal with pedestrians crossing at any time and place, including between you and the car ahead if you come to a stop, or if there's more than a couple meters between you and the next car. Even busy arterial roads will have to deal with people walking across them if there are large gaps or the traffic is slow or stalled.
In practice nobody steps out in front of a moving vehicle (for obvious reasons) and most people cross at the crossings most of the time because that makes sense.
In situations where there are a lot of people at the same time, like say a music festival or a sports game finishing, the police tend to manage the flow of people.
I'm struggling to believe London Brigde area and the square mile get 5x less congested than New York. What areas of London and New York are we comparing?
Greater London compared to Manhattan, apparently. https://en.wikipedia.org/wiki/Greater_London. I don't see what conclusions can be drawn from that comparison, which is why I asked GP to be explicit.
I don't think that's not very comparable. You don't get that many high rise residential buildings in central London, but it gets all the workers anyway. It's not as extreme, but think of Shibuya crossing having 0 population. We'd need some measure of people on the streets instead.
London is the densest, but the comparison was between the central area of one city and the entire area of another, perhaps even including suburbs beyond the formal city limits of the second. When you're leave out enough detail and just post two numbers, you're apt to make such mistakes while posting and thereby post something meaningless.
One good way to avoid posting meaninglessly is to write meaningful sentences and explain your conclusions/inferences explicitly.
