Wales to introduce widespread 20mph zones

[Helvellyn]

The problem with either of those processes is that it depends on speed limits being a tool for road safety, whereas in many areas they are provably not so (see emissions related limits on otherwise perfectly safe roads), so the law is already being used for non-safety based speed enforcement.

Emissions-related limits are not particularly common, and I'd argue are also not really an appropriate use for speed limits.

Wales has a number of them such as the A470 at Pontypridd (70mph D2 limited to 50), a limit so out of place for the road conditions they had to put average speed monitoring up and have to keep reminding folks that its actually enforced.

There's also the A494 at Deeside, though you could possibly argue that's congestion management rather than emissions, but the point stands. Once you start using speed limits for non-safety related reasons they become disregarded, because its an obvious and undeniable example of what many drivers have believed for years, that speed limits aren't set with safety in mind but for political reasons.

Sure, but if you don't live near one the odds of encountering them frequently are pretty low.

You put your finger on why I disagree with using speed limits for non-safety reasons though (and emissions-related ones get even more absurd if you're driving an electric car).

[Bryn666]

The problem with either of those processes is that it depends on speed limits being a tool for road safety, whereas in many areas they are provably not so (see emissions related limits on otherwise perfectly safe roads), so the law is already being used for non-safety based speed enforcement.

Emissions-related limits are not particularly common, and I'd argue are also not really an appropriate use for speed limits.

Wales has a number of them such as the A470 at Pontypridd (70mph D2 limited to 50), a limit so out of place for the road conditions they had to put average speed monitoring up and have to keep reminding folks that its actually enforced.

There's also the A494 at Deeside, though you could possibly argue that's congestion management rather than emissions, but the point stands. Once you start using speed limits for non-safety related reasons they become disregarded, because its an obvious and undeniable example of what many drivers have believed for years, that speed limits aren't set with safety in mind but for political reasons.

Speed limits have always been politically set; 30 mph was conjured up from in the first place as an arbitrary number chosen because that is what most vehicles could achieve without blowing up or constantly stalling in 1936, it had very little safety basis whatsoever. People still died horribly in crashes because of plate glass windscreens and no seat belts as well as open top cars overturning. A pedestrian impact at 30 has always been potentially fatal, kinetic energy transfer is a simple concept that the likes of the ABD and SafeSpeed have never disproven.

It is very difficult, however, to appreciate that you're in an urban area such as on the A483 at Wrexham when all you can see is dense vegetation either side. I'm also not entirely sure how air quality can be terrible in that location but someone must have been doing the research. If speed limits are deviating from what the road communicates to drivers then the design of the road is wrong.

[Helvellyn]

It is very difficult, however, to appreciate that you're in an urban area such as on the A483 at Wrexham when all you can see is dense vegetation either side. I'm also not entirely sure how air quality can be terrible in that location but someone must have been doing the research. If speed limits are deviating from what the road communicates to drivers then the design of the road is wrong.

And on this I completely agree. If there are good reasons for reducing speeds then they should be achieved by engineering, although of course that's rather more expensive than signs. But it's also why I'm unimpressed with 20 mph limits in residential streets; such roads are often self-enforcing to around 20 (or less) anyway, what with often not being that wide and lined with parked cars; those going noticeably faster most likely being the types to ignore limits anyway.

For emissions does 20 actually help? Most combustion engined vehicles will be less efficient at that speed than 30, although conversely there's less accelerating going on.

[rhyds]

Emissions-related limits are not particularly common, and I'd argue are also not really an appropriate use for speed limits.

Wales has a number of them such as the A470 at Pontypridd (70mph D2 limited to 50), a limit so out of place for the road conditions they had to put average speed monitoring up and have to keep reminding folks that its actually enforced.

There's also the A494 at Deeside, though you could possibly argue that's congestion management rather than emissions, but the point stands. Once you start using speed limits for non-safety related reasons they become disregarded, because its an obvious and undeniable example of what many drivers have believed for years, that speed limits aren't set with safety in mind but for political reasons.

Speed limits have always been politically set; 30 mph was conjured up from in the first place as an arbitrary number chosen because that is what most vehicles could achieve without blowing up or constantly stalling in 1936, it had very little safety basis whatsoever. People still died horribly in crashes because of plate glass windscreens and no seat belts as well as open top cars overturning. A pedestrian impact at 30 has always been potentially fatal, kinetic energy transfer is a simple concept that the likes of the ABD and SafeSpeed have never disproven.

It is very difficult, however, to appreciate that you're in an urban area such as on the A483 at Wrexham when all you can see is dense vegetation either side. I'm also not entirely sure how air quality can be terrible in that location but someone must have been doing the research. If speed limits are deviating from what the road communicates to drivers then the design of the road is wrong.

The A483 limit is totally pointless, especially when you consider that Wrexham's air quality is the best its ever been as both the coal and steelmaking industries have been dead for 30 years.

[Bryn666]

The faster way to reduce emissions would be to rebuild streets so people didn't drive everywhere but apparently that is evil and can't be done so once again the people complaining about that being a undesirable outcome are to blame for the current undesirable outcome.

[ajuk]

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.

[Bryn666]

The problem isn't the law, the problem is inappropriate design requirements to comply with the law.

DMRB's requirements for a 30 mph road result in a design that would make the Monza autodrome jealous. There is no need for 30 mph roads to have 7% superelevation on curves and radii bigger than 90m but that is what we are told to design.

Thankfully in recent years we have introduced Manual for Streets 2 in urban areas which takes all that and throws it away in favour of much more sensible design.

Unfortunately elsewhere highways planning dinosaurs still want big DMRB roads with low speed limits - see the A555 for a classic example of a road that should be 60 mph (there are peds and cyclists using a shared route alongside the carriageway and there are at-grade signal junctions so I'd not support 70) but DMRB makes it be 50.

In the USA you have ridiculous highway designs orientated for cars and no-one else, meaning that a six lane arterial road gets slapped with a 25 limit because the local police sense a good way to pick off out of towners. That's even worse than what we have; at least our speed enforcement policies have to be justified somewhat.

[ravenbluemoon]

SMT Note: Sorry, but I'm locking this thread temporarily in order to let things calm down. We have had some reports and therefore we need to take a look at actions to take.

We will unlock the thread in due course.

[ravenbluemoon]

SMT Note: I have removed several posts which contained unacceptable snarkiness and personal attacks.

Some folk on here don't get on, and it's obvious that the weather back in the UK is getting folks irritable. I don't care... follow the posting guidelines! Use the ignore function, don't rise to the bait, keep debate civil.

Thread reopened. Should things escalate again then I'll shut the thread permanently.

[ajuk]

Abergavenny was one of the towns selected to try out the 20 mph zones before their widespread introduction and I noticed for the first time I went to the town recently its almost a blanket 20 mph everywhere, such as this street on the A4143, which used to be the former railway line and has no residential properties, a few industrial units and only the occasional pedestrian.
https://goo.gl/maps/MYUUu6BuMCmviJNB7
30 mph used to feel slow if it was quiet and at 20 mph you feel like jumping out of the car and running quicker!

Some places have gone with such a blanket approach they included the Caldicot bypass, that was designed for a 40 limit and there was 97% non-compliance with that! That's created so much tension it's already caused accidents and someone was a hit by a car overtaking, this is what happens when there is a refusal to account for real world behaviour.
I've seen 20mph advocates speak out against the inclusion of certain roads before, so I hope they change this, the law is meant to allow to exempt higher standard roads. Anyway I digress, I came here to ask if this will this require repeaters?

[Helvellyn]

I've seen 20mph advocates speak out against the inclusion of certain roads before, so I hope they change this, the law is meant to allow to exempt higher standard roads. Anyway I digress, I came here to ask if this will this require repeaters?

20 mph zones don't, although they're supposed to be self-enforcing due to the nature of the road. Of course if it's a law change then the law can be changed to "no repeaters" anyway.

[hoagy_ytfc]

although conversely there's less accelerating going on.

And at 20 one can presumably go way further on pure electric, for cars that can do such things.

[ajuk]

I've seen 20mph advocates speak out against the inclusion of certain roads before, so I hope they change this, the law is meant to allow to exempt higher standard roads. Anyway I digress, I came here to ask if this will this require repeaters?

20 mph zones don't, although they're supposed to be self-enforcing due to the nature of the road. Of course if it's a law change then the law can be changed to "no repeaters" anyway.

Yes, for 20 zones, the thread title is incorrect it should say "Widespread 20mph limits.", can the Welsh government allow no repeaters? I think that's why it's going to cost so much, because it will all need repeaters.

[jnty]

I thought that the idea would be that the restricted road speed limit goes down to 20? So no repeaters required as currently is the case for 30s, and it would be the 30mph arterial roads that would require repeaters.

[orudge]

Will we see European-style speed limit country signs appearing at border crossings (with a “20” next to a town symbol) I wonder?

[JF2309]

When you stop and think about it. Its crazy that we allow a couple of tonnes of metal being driven by our peers (And have you met some of them? Jeez) within yards of other human beings just walking around going about their business. So for me. Slowing cars down in urban areas where NMU and Vehicle Conflicts are unavoidable can only be a good thing for safety, peace of mind and the general ambiance of the area.

[Big L]

When you stop and think about it. Its crazy that we allow a couple of tonnes of metal being driven by our peers (And have you met some of them? Jeez) within yards of other human beings just walking around going about their business. So for me. Slowing cars down in urban areas where NMU and Vehicle Conflicts are unavoidable can only be a good thing for safety, peace of mind and the general ambiance of the area.

Yes, if it was targeted, backed up with better engineering than just throwing some speed limit signs up, and enforced.

20 everywhere there are a few buildings is not a good policy.

[Chris5156]

I thought that the idea would be that the restricted road speed limit goes down to 20? So no repeaters required as currently is the case for 30s, and it would be the 30mph arterial roads that would require repeaters.

This was my lazy assumption too, but I have to admit I don't know without doing some research whether the Welsh Government has sufficient devolved powers to do that. It probably does since I think most transport powers are devolved now.

[JF2309]

When you stop and think about it. Its crazy that we allow a couple of tonnes of metal being driven by our peers (And have you met some of them? Jeez) within yards of other human beings just walking around going about their business. So for me. Slowing cars down in urban areas where NMU and Vehicle Conflicts are unavoidable can only be a good thing for safety, peace of mind and the general ambiance of the area.

Yes, if it was targeted, backed up with better engineering than just throwing some speed limit signs up, and enforced.

20 everywhere there are a few buildings is not a good policy.

Ok, but why? For a start ‘targeting’ limits just creates a massive inconsistency over an entire country in this case. That will create its own confusion, uniformity removes that.

Are really short hyper local journeys going to be disproportionately affected by a lowering of a Speed Limit by 10mph over Public Safety and the Environment in the broader sense, not just emissions?

I prefer to live in places that allow people to get about by all means of transport, be that using their own feet or by car. This strikes a happy medium.

Nobody is going to take your cars away, nobody is going to dig up our roads and replace them, they will still be their, we’re just being asked to drive a little bit slower in busy built up areas because human beings on foot are nearby and our cars provide a provable risk to their safety. Nothing really wrong with that.

[Bomag]

I thought that the idea would be that the restricted road speed limit goes down to 20? So no repeaters required as currently is the case for 30s, and it would be the 30mph arterial roads that would require repeaters.

The omission of repeaters is fixed in TSRGD 2016 for 30 mph only. The way TSM is written defines what is adequate signing under RTRA 1984 Section 85 and would require amendment. While setting of what is NSL is devolved this does not apply to all signing aspects.

To respond to several assertions, reducing the speed limit without altering the underlying design speed is not very effective and is less and less effective the lower the limit goes. This is why for temporary limits TSM Chapter 8 adopts the principle of highest safe speed.