jnty wrote: ↑Thu Jul 14, 2022 15:07
Chris Bertram wrote: ↑Thu Jul 14, 2022 14:32
solocle wrote: ↑Thu Jul 14, 2022 13:46
20 mph as a default in urban areas makes sense to me.
Residential areas, shopping streets? Think of how many roads where a 20 is appropriate.
Compare the number of arterial roads, A, B, or C, where 30 or higher is appropriate.
Passing TROs for a small number of roads is easier than for a large number of roads. Signing arterials with 30/40 repeaters makes far more sense than residential streets. And it makes missing signs at the entrances less of an issue, because, if you're turning, the presumption will be of a lower speed limit.
Unfortunately it looks like the implementation is going to include a lot of those arterial roads as 20s. But that doesn't mean the overall idea is bad.
But what is the overall real world effect of reducing speed limits to 20? Evidence suggests that you might, on a good day, reduce overall speeds by a massive 1mph if you're lucky, in the absence of oppressive levels of enforcement anyway. Which suggests to me that the money that will be spent on implementing the limits is pretty much wasted. Is it really such a good idea? Even shopping and residential areas will have quiet times when 30 would be both safe and reasonable, but it will now be illegal; should we be criminalising behaviour that is safe and reasonable?
I understand that the generally accepted figure is that a 1mph drop in average speed reduces injuries by 5%, so not to be sniffed at. In Edinburgh, crashes
fell by a third although obviously some of that drop would probably have happened anyway.
Road law regularly criminalises behaviour that is 'safe and reasonable' - such behaviour might include waiting on pedestrian crossing zig-zags when nobody is around, running a red light turning left when it's obviously clear to go or even nipping the wrong way up a one way street when it's quiet and clear. But we accept that there must be some degree of absolutism and you can't always simply trust people's judgement, especially en masse.
You may find that most people breaking the speed limit (
on roads where the limit does not match the road standard) don't also go robbing old ladies.
You're more likely to find the same people stopping for red lights, going slowly along narrow residential streets, passing cyclists with plenty of space, slowing down for hazards, waving people across the road or going around offering people free hugs.
It turns out most people generally tend to be agreeable and reasonable and have an aversion to having crashes or running people over.
So, when you find that a road has over 90% non-compliance, what's going on there?
If you look at roads that have seemingly generous speed limits, compliance is normally
much higher, but speeds aren't.
Either that's just a big coincidence, or there's more going on there. The
Strong Towns video I've posted before goes more into the phycology of this.
Even if I accept that people can't be trusted "
en masse". That's just you saying you have contempt the majority of people's driving ability.
If the law comes across as unreasonable or arbitrary, people not just then have contempt for that law, but also the people who set that law, the people who enforce that law and even the people who obey that law. Yet these limits are being set by people who claim to want exactly the opposite of that.
That 1mph drop is also to the detriment of almost all compliance and it's not normally because the very fastest are slowing down, they don't pay any attention to speed limits and they're some of the most likely to do harm but they're also the drivers speed limits are meant to be singling out.