[squidgyhead]

Speed enforcement has been extensively studied, and there are a lot of publicly available articles on the subject. The results are basically universally in favour of speed enforcement reducing motor vehicle collisions, reducing injury and cost.

[IshKebab]

> The results are basically universally in favour of speed enforcement reducing motor vehicle collisions, reducing injury and cost.

Yeah this argument comes up a lot in the UK from people advocating 20mph speed limits everywhere. It's a super dumb argument though. Obviously increasing speed is never going to decrease danger. But if "slower is safer" is the only argument for 20mph then the logical conclusion is 0mph.

Clearly there are other factors at play, but the 20mph people never acknowledge that for some reason...

(To be clear I'm not advocating for 30mph everywhere. I feel like 25mph is actually the best trade-off for most suburban roads.)

[lonelyasacloud]

It is very hard to think clearly about driving too fast given both how much fun it is and the monumental amounts of money that the car industry has pumped over decades into promoting their empty road, drive fast without consequences propaganda within our societies.

However, as with tobacco, the evidence cannot be papered over forever and there are many studies that indicate they are a bad idea (tm) in urban environments. And in particular with respect to the setting of speed limits that they should be lower than many of us have been influenced to think because the rate of injury and death increases disproportionately with speed.

For instance https://www.who.int/news-room/fact-sheets/detail/road-traffi... states that a "1% increase in mean speed produces a 4% increase in the fatal crash risk and a 3% increase in the serious crash risk". And that for pedestrians "The risk of death for pedestrians hit by car fronts rises rapidly (4.5 times from 50 km/h to: 65 km/h.".

So yes, slower is safer - not in some reductio ad absurdum sense that implies '0mph', but in a public health sense where a fair and practical compromise should be sought.

To my mind, 15 - 20mph in urban areas is that compromise.

It allows practical vehicle use, while also respecting the rights of other road users - especially pedestrians and cyclists - to exist and move about without significantly elevated risk.

The idea that some people should be granted the ability to move through shared space at speeds that make them dangerous beyond anyone else simply because they're encased in a car is not just unfair - it creates noisy, dangerous, and ultimately unliveable environments.

[IshKebab]

> So yes, slower is safer - not in some reductio ad absurdum sense that implies '0mph', but in a public health sense where a fair and practical compromise should be sought.

> To my mind, 15 - 20mph in urban areas is that compromise.

This is precisely my point. None of the "slower is safer" people even acknowledge that it is a compromise. Their entire argument is "slower is safer" which does lead to 0mph.

It's impossible to have a proper debate if some people are saying "I know slower is safer but I don't want to go at 20mph everywhere" and others are saying "but... it's safer!"

[graemep]

My problem with the 20mph speed limits in the UK is that they seem to be imposed fairly randomly.

There are many cases where wide roads with good visibility and few pedestrians crossing have 20mph limits. In one egregious case I experienced recently near identical stretches of the same road (it was a main road, I think an A road, passing through a built up area) switched between 20 and 30 mph limits. If anything it created a significant distraction keeping track of the limits.

There are a number of other roads like that have 20mph limits. On the other hand narrower side roads in the same areas has 30mph limits.

My road has a 20mph limit. On the bit I live on it makes no difference - narrower, parked cars etc. means you drive very slow anyway. Further down the road is broader and clearer. I think the reason maybe to encourage people to use the bypass instead of driving through the village so it may be reasoned- although I suspect the speed bumps are more effective at doing that.

[Mawr]

> There are many cases where wide roads with good visibility and few pedestrians crossing have 20mph limits.

> My road has a 20mph limit. On the bit I live on it makes no difference - narrower, parked cars etc. means you drive very slow anyway.

Make up your mind ;)

[Dylan16807]

There are many cases, and the bit where they live is not one, but a nearby bit is one.

If you're making a joke I don't get it. Can you explain it?

[pbhjpbhj]

20-to-30 causes a step change in pedestrian outcomes, so no, the logical conclusion isn't 0mph. Also the average speed on 30mph roads before the changeover was around 20mph.

It improves traffic flow and reduces pollution too.

My only objection is that it's been applied in a somewhat blind way. Long sections of road with no houses and no reported accidents should probably be 30, or even 40mph.

[Dylan16807]

https://ars.els-cdn.com/content/image/1-s2.0-S00014575193010...

I don't really see a step change between 32kph and 48kph.

[IshKebab]

> the logical conclusion isn't 0mph

Yes it is. If the only thing you consider is safety then 0mph is the safest. That's unarguable.

The point is that you can't only consider safety. There are other factors, but they are often deliberately ignored.

[pbhjpbhj]

Well also we need to kill everyone so noone can die, the only logical conclusion.

If that's your best argument _against_ saving lives through road traffic controls then at least we know it's not wrong...

I hope your computer is completely unsecured, because if you cared about security you wouldn't even use the web.

[rtpg]

I think we do in practice apply 0mph (i.e. banning cars) in some major cities, turning roads into pedestrian areas! 0mph happens!

It's obviously a trade between various participants, who have their own interests. 30km/h limits have had good success. If people think the number of fatalities is a problem, there's a solution waiting for you.

[Mawr]

> But if "slower is safer" is the only argument for 20mph then the logical conclusion is 0mph.

Hilariously wrong. Kinetic energy is equal to mass times velocity squared divided by half. That squaring of velocity kills your argument.

[lukan]

Can you explain what you mean?

The argument is, going 0 mph, meaning not driving at all is safer than even slow driving. Meaning the argument is, there has to be a compromise, all driving is dangerous.

[gmac]

Speed, of course, affects not just how many accidents there are but also how bad they are. A key argument for 20mph is that collisions with pedestrians at this speed are mostly survivable. https://publications.parliament.uk/pa/cm200102/cmselect/cmtl...

[IshKebab]

> mostly survivable

Collisions at 15mph would be even more survivable though.

[bluescrn]

Zero MPH = zero traffic = zero road deaths.

But without transport significantly more people will die from other things, due to reduced access to healthcare, employment, food, etc.

In a modern society, road transport is a critical part of our life support system. Those pushing for a what they see as a car-free utopia tend to ignore this.

[wafflemaker]

30 km\h limit in densely populated and heavily used by pedestrians first\last 2-5 minutes of your travel does what? Extends your travel time by 1 minute? At the same time making it nearly impossible to kill a kid, cat, dog or human in these places.

Same goes with the right of way in these places. You're in a car, you're getting where you're going much faster anyway, so you let pedestrians go first. On pedestrian crossings, and often even without them in such "last leg" places.

It's completely logical. You don't go faster in places where somebody can suddenly walk out from behind a parked car, bush, whatever. But it's a cultural thing in Scandinavia.

[throwaway9832]

You, just like the grandparent, confuse egregious 0% tolerance speed enforcement with speed limits. Speed limits dictates stopping distance and is a key factor in collision avoidance. No one is asking to abolish speed limits.

The problem is when passenger cars that require a fraction of stopping distance of a truck at given speed limit are fined for going 3-4 km over limit. Essentially, fined for driving at a speed where they can stop many meters before a truck going the sign posted limit. Revenue raising in the name of safety, down playing other factors like attention, driver training, road design, maintenance, and so on, but they don't bring as much money.

[macguillicuddy]

I don't see anything in the parent comments referencing or advocating for 0% tolerance speed enforcement. In the UK speed limits are typically enforced with a 10% grace factor.

[bluescrn]

Instead, there's a push to reduce limits ever closer to zero.

30mph was close to the sweet spot and had been for decades. Or it would have been with a reasonable level of enforcement.

But as the ideological and/or climate-driven war on cars ramped up there's been a big push to reduce ever-more areas to 20mph, which is just too slow, especially when deployed widely/indiscriminately as it has been in Wales. (Used very sparingly, e.g. outside schools, 20mph limits were a good 'take particular care' signal to motorists - but that effect is lost when they're widespread)

Is it really about safety or is it about 'fuck cars'?

[Xylakant]

If you look at outcomes, 50km/h (30mph) is much less safe than 30km/h (20mph). If you look at the physics, that’s not surprising - stopping distances increase super linear. At the point where a 30km/h car would have come to a stop, a 50km/h car still impacts with 30km/h.

On the other hand, average speeds in populated areas usually are way lower than 30km/h, so lowering the top speed to 30km has negligible effect on travel times.

If you consider 50km/h the sweet spot, you prioritize vehicle speed over the very real risk of bodily harm for all other traffic participants.

[Mawr]

> 30mph was close to the sweet spot and had been for decades.

For car drivers maybe. From the POV of a pedestrian, 30 mph is very fast.

[hvb2]

So, assuming you do support some enforcement for passenger cars, at what speed would a ticket be warranted? Because this is exactly the dumb setup they have in California for example.

Speed limit is 65, everyone is doing 80. When you pull over someone how do you explain why only that person gets a ticket?

A limit is only a limit when it's enforced. Anything else will become arbitrary.

[formerly_proven]

You go 30 km/h. A kid runs on the street. You manage to stop just in front of it.

You go 40 km/h. The same kid runs on the same street. You brake the exact same way. You hit the kid with over 30 km/h. You just killed a kid.

[bluescrn]

Kids don't run out into the street chasing stray footballs anymore. They're all indoors staring at screens.

[Mawr]

> cars that require a fraction of stopping distance of a truck at given speed

You may want to update your knowledge on the stopping distances of modern trucks.

> are fined for going 3-4 km over limit

Obviously. Is there anything confusing about the word "limit" in particular that you don't understand?

> Essentially, fined for driving at a speed where they can stop many meters before a truck going the sign posted limit.

It is not your job as a driver to decide whether to stick to a particular traffic rule or not. The limit is there, so follow it.

[aziaziazi]

There was a study [0] in Paris that demonstrates a signifiant life expectancy and positive benefit/risk ratio of bicycling or commuting by public transports: the effect on physical and psychic health largely outweighs (sometimes to x30) the risk of accidents and pollution disease.

> without transport

Nobody argues to remove all cars altogether, and certainly not other forms of transport. However we certainly can rethink the millions of individual cars in each cities: does everybody needs its own 1ton vehicle to bring food back from the local supermarket? To go to work 2-20km away?

[0] (2012, french) https://www.ors-idf.org/nos-travaux/publications/les-benefic...

[exe34]

It's almost as if a balance could be achieved, both by reducing the number of cars and increasing the number of trains/busses.

[rwyinuse]

Yep. Something worth considering is also building long-term parking spaces to the outskirts of cities, accessible with public transport. I know lots of city-dwellers who pretty much never use a car for intra-city transport, but need to own one anyway to reach other important places that are beyond reach of public transport.

In case of Finland summer cottages are one such case. They're extremely common, and located in areas that usually have no public transport. Lots of people have also older relatives who live in middle of nothing.

[hdgvhicv]

Surely car hire would make more sense for that type of usage

[rwyinuse]

It's pretty common for people to stay in their summer cottages for a week or more, several times a summer. Renting a car for all that time gets very expensive, and it will be just sitting idle most of the time. At that point you may as well just buy a cheap used car for the same yearly cost.

The need for car ownership would plummet if we had self-driving cars that can autonomously drive back to the city, and to pick you up from the countryside.

[bluescrn]

Only in cities. And a lot of people don't want to live in ever-denser cities.

[graemep]

A lot of people seem to want to live in cities though. Scroll through this graph, especially the broad categories at the bottom of the page, and there is a consistent global trend to urbanisation: https://data.worldbank.org/indicator/SP.URB.TOTL.IN.ZS?locat...

House prices are almost far higher in big dense cities, so people are clearly willing to pay a premium to live there.

People either want or need to live in big cities.

[exe34]

I live in a small village on top of a hill. Most people drive, but I don't. When I need to get some heavy stuff up the hill once a month or two, I get the bus. The rest of the time I walk.