OV9

I live in the Vale of Glamorgan, between Cardiff and Bridgend. I don’t have an issue with the new speed limits. Initially, 20mph seemed too slow, almost walking pace. But now that I’ve adjusted, the limits seem sensible and generally located in residential areas only. There are a few odd exceptions, but I’ve simply assumed I’ve missed something. My journeys aren’t recognisably longer. I also find driving through residential areas less stressful (except when I have someone glued to my bumper). The safety, environment and air quality improvements seems a sensible benefit to justify the lower speed.

I don’t understand the vitriol against the lower speed limit.

I don't understand the air quality claim. Cars are more efficient at 30 than 20.

Simon wrote: ↑Wed Dec 13, 2023 3:09 pm I don't understand the air quality claim. Cars are more efficient at 30 than 20.

That. See also speed bumps and other “calming” methods that cause vehicles to slow or stop. Stoopids.

mik wrote: ↑Wed Dec 13, 2023 3:53 pm

Simon wrote: ↑Wed Dec 13, 2023 3:09 pm I don't understand the air quality claim. Cars are more efficient at 30 than 20.

That. See also speed bumps and other “calming” methods that cause vehicles to slow or stop. Stoopids.

Is anyone seriously claiming that 20 though a rural village with minimal traffic is making any difference whatsoever to air quality?

Now that Drakeford has resigned maybe there's a chance they'll see sense?

The few 20mph zones I've had experience with are tedious, far too long and appear to be through dead town centres anyway ie: no pedestrians anyway..

scotta wrote: ↑Wed Dec 13, 2023 4:14 pm
Is anyone seriously claiming that 20 though a rural village with minimal traffic is making any difference whatsoever to air quality?

Welsh Government. See bottom of page10. They suggest an improvement, wit worst case of "neutral impact"....

https://www.gov.wales/sites/default/fil ... t-2018.pdf

Something I didn't think about until my mate from Hong Kong mentioned it "We have some of the worst air quality in the world in HK but one of the highest life expectancies - I don't think cars are the problem"
The elephant in the room is rather obvious.

Ynys Llanddwyn wrote: ↑Wed Dec 13, 2023 2:53 pm I live in the Vale of Glamorgan, between Cardiff and Bridgend. I don’t have an issue with the new speed limits. Initially, 20mph seemed too slow, almost walking pace. But now that I’ve adjusted, the limits seem sensible and generally located in residential areas only. There are a few odd exceptions, but I’ve simply assumed I’ve missed something. My journeys aren’t recognisably longer. I also find driving through residential areas less stressful (except when I have someone glued to my bumper). The safety, environment and air quality improvements seems a sensible benefit to justify the lower speed.

I don’t understand the vitriol against the lower speed limit.

Have you driven up and down the valleys (eg A469 to Rhymney) where there are long 20 limits which definitely do affect journey time?

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Have you driven up and down the valleys (eg A469 to Rhymney) where there are long 20 limits which definitely do affect journey time?
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No, I haven’t driven in the Valleys since the reduced speed limit was introduced. The linear nature of villages in the Valleys would result in longer lengths of reduced traffic speeds. What would the reduced limit add to journey lengths? A simple comparison of 10 miles at 30/20mph suggests a 10 minute journey increase. Is the speed limit the main contributing factor or the general capacity of the road infrastructure in the Valleys?

Interesting analysis of the benefits of the 20mph limit from Welsh Gov’t.

Air quality - “air quality is likely to be improved as a result of 20mph speed limits but the evidence is weak.”

Safety - “For casualty reduction the evidence is consistent that casualties are reduced as a result of 20mph speed limits. The evidence is moderate to strong.”

Ynys Llanddwyn wrote: ↑Thu Dec 14, 2023 1:56 pm No, I haven’t driven in the Valleys since the reduced speed limit was introduced. The linear nature of villages in the Valleys would result in longer lengths of reduced traffic speeds. What would the reduced limit add to journey lengths? A simple comparison of 10 miles at 30/20mph suggests a 10 minute journey increase. Is the speed limit the main contributing factor or the general capacity of the road infrastructure in the Valleys?

The A469 was the route I used to get home a couple of months ago on a Sunday morning. Not really any traffic up to the Heads of the Valleys road and it would have always been a bit of a slower route than one of the dual carriageways, but it's basically 10 miles of 20 limit for no safety benefit. So much so that the locals had vandalised a lot of the signs already.

20 is fine in a properly built up area but a straight A-road with some houses alongside and set back where you can see for the best part of a mile each way... no.

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20 is fine in a properly built up area but a straight A-road with some houses alongside and set back where you can see for the best part of a mile each way... no.
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I’m not going to disagree. In dense residential areas, with pedestrians, schools, retail and on street parking, the reduced speed limit makes sense to me. The example you describe, I’d be frustrated too.

@Ynys Llanddwyn

I think it's just a cut and paste issue - the start of quoted sections should have "quote" inside the [square brackets], with the end of the section showing "/quote". You can edit your posts using the little pencil symbol at the top right of the post.

https://www.bbc.co.uk/news/uk-wales-68056865

Review of the 20mph after 3 months, the average speed has dropped 2.4mph. From 22.7mph to 20.3mph

If the average speed was only 22.7 was it really worth pissing off an entire country

Will it drop more over time? It reminds me of a road near here where people had called for the speed limit to be reduced. It's in between two lower limits and when observations were made few people were seen travelling as fast as the limit, the average nearer the lower limits either end (something like 33 in a 40), so the proposed change was rejected. Cost was also mentioned, and that's for a short bit of road... I wonder what the Welsh averages were in different areas, residential to more open 30s? Of course speed doesn't tell the whole story, but I don't know if driver behaviour and traffic flow will be looked at as closely.

jamcg wrote: ↑Mon Jan 22, 2024 8:41 pm https://www.bbc.co.uk/news/uk-wales-68056865

Review of the 20mph after 3 months, the average speed has dropped 2.4mph. From 22.7mph to 20.3mph

If the average speed was only 22.7 was it really worth pissing off an entire country

Has the traffic level reduced too I wonder? I'm certainly avoiding Welsh towns where possible.

Barry wrote: ↑Tue Jan 23, 2024 11:40 am

jamcg wrote: ↑Mon Jan 22, 2024 8:41 pm https://www.bbc.co.uk/news/uk-wales-68056865

Review of the 20mph after 3 months, the average speed has dropped 2.4mph. From 22.7mph to 20.3mph

If the average speed was only 22.7 was it really worth pissing off an entire country

Has the traffic level reduced too I wonder? I'm certainly avoiding Welsh towns where possible.

Interesting stats - can be taken multiple ways without more detail :
1. Wasn't worth pissing everyone off when the average speed drop is minimal
2. It's clearly minimally impacted everyone, so why are you all moaning?

I'd be interested to know if speeds were already low in "obvious" areas around schools etc, but now lower on sections previously perfectly safe at 30 (like some of the 20-limits through quiet villages we have up here that I comply with, but don't see the point).

In my experience, the drivers who would happily buzz through a 30 limit at 45, are pretty much just as happy to buzz through a 20 limit at 45. Unless there is some increased enforcement, they aren't deterred.

Surely the measurable is whether accidents have reduced or not?

mik wrote: ↑Tue Jan 23, 2024 12:05 pm

In my experience, the drivers who would happily buzz through a 30 limit at 45, are pretty much just as happy to buzz through a 20 limit at 45. Unless there is some increased enforcement, they aren't deterred.

100% this. Also those rare cases of someone doing drink/drugs/dangerous driving and crashing and killing themselves or someone else by going 80 mph on a 20/30/40 road will not be affected even if the speed limit is 5 mph.

In software/product management, we often find ourselves talking about outputs vs outcomes

This data from Wales reminded me of this

The average speed dropping is an output

But the impact of that would be an outcome

Has the number of accidents/injuries changed?

Usually speaking, it's harder to ask "so what?" to an outcome vs an output (a good way to differentiate)

In software terms, "a drop in average speeds" would be akin to "we launched a new feature" - on it's own, it doesn't really mean anything

The effect that feature has, is the important part...

All absolutely correct, but you're dealing with idiot politicians and policy makers who can't think of complicated effects like that. All they know is 'big number bad, small number good'. Same goes for most of the public TBH.