[skippyboxedhero]

Other places have introduced the same limit and haven't seen the same results.

People who are likely to have crashes are likely to be able who ignore the limit. One of the biggest problems in modern policy-making is the introduction of wide-ranging, global policies to tackle a local problem (one place that introduced this limit was Wales, they introduced this limit impacting everyone...but don't do anything about the significant and visible increase in the numbers of people driving without a licence which is causing more accidents...and, ironically, making their speed limit changes look worse than they probably are).

[arp242]

"First 20mph year sees 100 fewer killed or badly hurt" https://www.bbc.co.uk/news/articles/c78w1891z03o

So no, what you're saying is bollocks. And no one ever claimed that speed limits are the only solution.

[mtrovo]

Your example is definitely not a good example of global policies for a local problem. In Wales it was up to the local councils to identify areas that under proper safe circumstances would keep their different limits, defaulting to being reduced to 20mph if nothing was done. That's a very sensible way of handling it.

I have no idea about your stats on driving without a licence being more of a problem than speeding, accidents on roads that got the speed reduced to 20mph or 30mph decreased by 19% YoY, that's a big impact for mostly no additional policing needed.

[skippyboxedhero]

...you are just explaining that it was a global policy for a local problem. I don't know what to tell you. The global policy is 20mph.

It sounds like a big impact if you don't know anything about statistics because, obviously, you would need to know some measure of variance to work out whether a 19% YoY decrease was significant (and I don't believe the measure that reduced 19% was accidents either). This hasn't been reported deliberatel but that is a single year and that is within error. You, obviously, do need more policing...I am not sure why you assume that no policing is required.

People driving without a licence/insurance are more of a problem than someone going 30mph...obviously. Iirc, their rate for being involved in accidents is 5x higher. If you are caught doing either of these things though, the consequences are low. Competent driver going 30mph though? Terrible (there is also a reason why this is the case, unlicenced/uninsured driving is very prevalent in certain areas of the UK).

[mtrovo]

That's not how a global policy works is it? The process was closer to a central guidance with enough notice for local councils to override it if they had the means to justify it.

You don't need additional policing as you can reuse most of the speed limit infra that's already in place, just the baseline that has changed. It's orders of magnitude easier compared to the effort to catch a single unlicensed uninsured driver.

And regarding the stats: the official report is just one google away https://www.gov.wales/police-recorded-road-collisions-2024-p.... The numbers are declining in the last decade but it accelerated to rates not seeing in the past apart from the pandemic.

> These collisions on 20 and 30mph road speed limits (combined), resulted in 1,751 casualties, the lowest figure recorded since records began. This was a 20% decrease from the previous year, the largest annual fall apart from 2020 (during the COVID-19 pandemic).

About collisions: > ... It is also 32% lower than the same quarter in 2022 (the last quarter 4 period before the change in default speed limit)

And casualities: > ... The number of casualties on roads with 20 and 30mph road speed limits (combined) in 2024 Q4 was the lowest quarter 4 figures in Wales since records began.

There's no mention of widespread licence or insurance compliance problems on the official report so not sure where you're taking this as a significant problem.

[crote]

> People who are likely to have crashes are likely to be able who ignore the limit.

... which is why you have to do actual road design. You can't just put up a speed sign and hope people will magically abide by it. Roads need to be designed for the speed you want people to drive. When done properly the vast majority of drivers will follow the speed limit without ever having to look at the signs, because it'll be the speed they will feel comfortable driving.

[DFHippie]

> You can't just put up a speed sign and hope people will magically abide by it.

Off topic, but one of the more maddening things I see here in the US is signs which say "End thus-and-such speed limit." I don't want to know what the speed limit was. I want to know what it is!

[frosted-flakes]

In Ontario a new speed zone is always signed with "BEGINS" below it, which is very helpful if you missed the last sign. I wish this was standard practice across Canada.

In much of Europe, including the UK, they have the concept of standardised "national" speed limits, which vary depending on the road type and which you are expected to know. When a road returns to the national speed limit, the sign is a white circle with a slash through it, indicating that there are no more local speed limits and the national speed limit is in effect.

[Symbiote]

There are at most three standard speed limits on Europe: built up areas, highways and motorways.

I find this easier to remember than the constantly changing limits in the USA. In my two weeks here, I've seen every multiple of 5 between 5 and 70mph.

[kqr]

In Sweden at least, there's an informal rule that a new speed zone is marked with speed limit signs on both sides of the road, whereas a continued limit is marked with a sign only on the driving side of the road.

I never quite saw the point though -- my response is the same either way: adhere to the limit that applies going forward. (I suppose maybe it's useful feedback of inattention and the need for rest?)

[cluckindan]

Proper design of road networks also makes traffic flow better. Many congested areas would actually benefit from removing some roads altogether.

[perching_aix]

I believe you're referring to Braess' Paradox, right? This was a very surprising effect for me to learn about, just recently Veritasium covered it in their video on a mechanism that becomes "shorter when you pull on it": https://www.youtube.com/watch?v=-QTkPfq7w1A

[0] https://en.wikipedia.org/wiki/Braess%27_paradox

[cluckindan]

Yes, I saw the same video! Having played Cities: Skylines, it was not that much of a surprise, more of a neat formal explanation.

[skippyboxedhero]

It isn't road design, it is behavioural/cultural. People will drive recklessly when they do not care, for whatever reason, about the people they may injure by doing so. That is it. If you look at comparisons between countries, it is clear that means are different.

[jfengel]

There are people who don't care at all, but most people will drive around the speed that the road encourages. That includes things like how straight the road is, what kinds of interactions, the presence of sidewalks, trees, and many other clues.

Neighborhoods can be designed to send signals about the appropriate speed, without signs or rumble strips or speed bumps. Some people will ignore these, just as they'll ignore signs, but most drivers will do what they expect for that kind of road.

[crote]

I disagree, idiots are everywhere.

The thing is, the vast majority of people - regardless of culture - have some basic sense of self-preservation. Speeding is easy when that 30km/h road is designed like a 120km/h highway. Speeding is a lot harder when that 30km/h road has speed bumps, chicanes, bottlenecks, and is paved with bricks rather than asphalt: if you try to speed, it'll quickly feel like you need to be a professional rally driver to keep your car under control.

Deliberately making roads "unsafe" forces people to slow down, which in turn actually makes it safe.

[gs17]

That's true. I stopped riding the bus because the road to the stop had big speed bumps put in, and it turns out distracted drivers fly off the road when they hit them, and one near miss was enough to make me drive instead (sure it's a cognitive bias, but it's enough to make me pick the more convenient option). One fewer pedestrian means one fewer potential pedestrian death!

[goopypoop]

…plus the potential pedestrian deaths you cause by collision plus the actual impact of the extra pollution