Sing it with me, folks…
You 👏 can’t 👏 reduce 👏 the 👏 speed 👏 limit 👏 without 👏 also 👏 changing 👏 the 👏 street 👏 geometry! IT DOESN’T FUCKING WORK!
People don’t give a shit about the what the speed limit sign says; they drive at the maximum speed at which they feel safe and comfortable based on the lane width, curve sharpness, etc. If you want to slow people down, you HAVE TO physically change the road – narrow it, add chicanes, etc. – to make it “feel” less safe. It’s not fucking optional!
(Source: my background in traffic engineering.)
To be clear, I’m not saying that the goal of reducing speeds is bad. I’m just saying that attempting to do so on the cheap by changing the rules instead of the built environment itself accomplishes nothing but to generate more lawbreaking. Well, that and potentially making the road even less safe than it was before because having a wider mix of speeds is even worse than having everybody at a uniformly too-high speed.
Absolutely right. My town just made every road 25mph. Great. Unfortunately nobody gives a fuck. The road out in front of my house just got repaved. It’s beautiful. I love it. Pulling in and out of my driveway has never been better. People also blast down it, mainly because I think they perceive speed differently on a nice smooth tarmac versus what was a cratered surface rivaling the moon. My suggestion to my neighbors is we just keep cars parked on the street all the time. If folks in opposing directions need to stick to a side to let others pass, it will naturally cause them to move more slowly.
Edit - Forgot to add, I listen to traffic engineers testify pretty regularly and consistently get mistreated, so I just want you to know that I appreciate what you’re saying and what you do.
My house is on a residential 25mph street with a slight S curve. There was a car parked at the end of the curve and a reckless driver managed to plow into it and flip their car. It was the wildest thing I’ve ever seen. You would expect something like this on an interstate highway, not a tree lined street with little kids playing.
Step 1: reduce speed limit
Step 2: always have speed trap in place
Step 3: profit
And do you slow down? If so, we just need stupid cheap speed cameras and deploy them fucking everywhere
I largely agree with you, but I also recently saw this article: https://www.euronews.com/next/2023/07/26/inventive-or-stupid-french-village-disorients-drivers-with-crisscrossed-white-lines
That seems more like an “and” than a “but,” since it’s a physical change to the road that makes it feel less safe. Anyway, nice find! I like how inventive and relatively inexpensive it is.
Speeds should be set using the 85th percentile rule: the speed limit is whatever speed the 85th percentile driver goes.
The thing, though, is we should work backwards from figuring out a desired speed for pedestrian + cyclist safety and then build a road with the desired 85th percentile speed.
Too often, it’s done exactly backwards.
It’s easy, just require speed governors in cars.
Where I live, they’re required in e scooters and e bikes, which are far less dangerous than cars
E-scooters and e-bikes don’t have speed limits that vary by street. In order to implement a governor capable of limiting a car to a 20 mph speed in certain areas while still allowing it to run at highway speeds in others, you’d need either a computer vision system to read the speed limit signs or a GPS paired with a perfectly complete and up-to-date speed limit geodatabase, and you’d need to give either such fallible computerized system control over the throttle (which could be a safety hazard in and of itself, for multiple reasons).
The difference between a e-bike governor and a car governor that can be set to something lower than 70 mph is like this.
Just have a 20 mph limit in the city, and no speed limit outside the city. This would also require moving all the highways outside the city, but I think that would be an improvement.
your background in traffic engineering included learning how much these modifications cost.
seems like if we can’t have your ideal we get nothing.
yeah, thanks, nope. but thanks for the ovation.
You seem to be under the impression that changing the speed limit sign is “better than nothing.”
It’s not.
It is, in fact, worse than nothing because having half the drivers comply with the lower speed limit and having half not creates a mix of speeds that’s even more dangerous than if everybody just drove at the same higher speed.
I’m dubious and don’t care enough to take the time. whatever mr traffic engineer, I guess we just can’t have nice communities because it’s even worse to TRY.
do you have any idea how pathetic it sounds? like a cult of apathy, doing anything is GOING TO COST MONEY genius… and even if it doesn’t work perfectly, it’s still better to try than throw your hands up in the air and accept dead pedestrians all the time.
you do you tho.
I think the main problem here is for folks forced to drive every day in the dervish of death that is rush hour.
If you can’t afford to live near where you work (as is often the case in the UK), and you’re already looking at a 1 hour commute both ways, current public transport isn’t an option. You can either give up on sleep, or you will have to drive.
A lot of these changes are coming in the wrong order - first you improve public transport, create affordable housing near city centers, and drastically reduce the price (and let’s be frank, increase the quality of) public transport, and THEN you hit car users to push them on to these options. In the current order, they just introduce further hardship to folks who already have a bad time.
A lot of these changes are coming in the wrong order - first you improve public transport, create affordable housing near city centers, and drastically reduce the price (and let’s be frank, increase the quality of) public transport, and THEN you hit car users to push them on to these options. In the current order, they just introduce further hardship to folks who already have a bad time.
It might be a little different in the UK, but in North America step #1 needs to be “first you abolish the low-density zoning restrictions that displace almost everybody far away from the city center to begin with.” It’s not just that walkable housing isn’t affordable; it’s that it’s not even allowed by law to exist.
There is another substantial difference. In Europe you have private spaces to park your car and then roughly as many public parking spots as there are cars. In the US you have about 8 times as many public parking spots as cars exist. The amount of concrete wastelands just for potential cars is incredible.
You could basically scrap ¾ of your parking spaces to create walkable areas with small shops beside the big malls or oversized markets, then do some public transport to those areas (or still drive by car there), just to establich the idea of walking while shopping.
That’s no replacement for getting rid of zoning regulations but a realistic start, where changing the zoning (even when the regulation vanish) would need a generation or more to change.
Yeah, the current approach globally - at least it seems to be the same in Germany - is to make the “experience”, if you want to call it that, for car users worse to the point that it’s worse than public transport in order to force people onto it. There are some minor improvements being made to public transport, but it’s of course a lot faster to put up signs for a speedlimit everywhere or even blocking access to certain roads completely than to increase the capacity of a rail network. And as you said, this hits the already disadvantaged parts of the population more, since they more often than not have manual labor type job that requires going into the “office” everyday, that are living further from work, …
That’s not some “approach” but a symptom of conservatives fighting change tooth and nails. And it’s always easier to destroy something. So while one side is trying to improve public transport and create proper bike infrastructure at the same time, the other side is sabotaging.
Missed one - you actively encourage mobile working so you have less people moving around in total.
I agree here, a larger push towards remote working would definitely help, though such a move would likely come at the expense of privacy (teams is already a privacy nightmare as it is, with wider home work adoption no doubt Microsoft would implement more “features for employers”).
Given that we know going over the speed limit raises your collision rate, meaning setting the speed limit so low every driver will go over it is genuinely dangerous, do we have any studies supporting the claim that reducing the speed limit reduces the collision rate overall? I couldn’t find one, but it’s a surprisingly challenging search - I easily found studies confirming that collision lethality scales with speed, but that’s not my question.
Purely anecdotally, the vast majority of my collisions have been at very low speeds - in parking lots.
Purely anecdotally, the vast majority of my collisions have been at very low speeds - in parking lots.
The fact that you talk like you have enough samples to make that inference worries me.
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Why will every driver go over 20mph/30kph? Are they incapable of maintaining that speed? All school and community zones in my country are 30kph; are we wasting our time with those?
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I’m a vision zero proponent, so I don’t care about the number of collisions; I care about the number of fatal collisions first, serious injuries second, minor injuries third. So even if 20 mph maintains, or even increases collisions; so long as it reduces casualties, it’s positive. Bumpers are replaceable; people are not. The AAA document you link even says a 10% reduction in mean speed reduces fatal crashes by ~34% in the executive summary.
Regarding the first point, drivers naturally trend towards the speed they “feel” is right. Also many modern cars practically idle faster than 20 once you get rolling.
Change the actual road to slow people down and reduce accidents.
I agree, but you are making excuses for bad driving. It’s still their fault that they drive too fast.
My main concern with this is that what you’re doing is desensitising people from the speed limit.
I’m from a country that has arbitrarily defined speed limits and VERY low compliance rates compared to the UK (if you’ve ever been to Italy for example you know what I’m talking about). The nice thing here is that because the vast majority of roads have a speed limit that ‘feels’ appropriate (ie the road is designed for its speed limit), the amount of speeding I see here is negligible compared to what I was used to.
And generally here when the limit changes people comply to it because you can trust there’s usually a good reason.
There’s roads near me that are arbitrarily set to 30 (no pedestrian walkways, no side roads, but it passes near the back of houses and I assume they successfully petitioned the local authority to change it to 30), and traffic flow there is usually 40-45. I’ve never seen an accident there.
We have a poorly designed intersection not too far away and there’s always accidents there to the point that there’s now a consultation to fix it.
If this rule came to England, both these roads would be turned to 20, and that won’t really be solving anything. In the first example I assume locals will still be driving 40, and it will create unnecessary overtaking because the road is wide and the visibility is good so it’s not necessarily unsafe. But you’ve gone from a safe 40 road to risking head-on collisions pointlessly.
Tons of European cities already set-up speed-limit to 30 km/h. It’s not just large cities, I’ve seen villaged limited at 30 too.
it’s basically less nuisance for the residents
Fine where alternatives are available. But this also would slow down busses, right?
We have this speed limit in the Netherlands, mostly in areas with housing. It doesn’t really affect busses because they stay on the bigger roads that are 50 kmh (about 31 mph). In my opinion it’s fine to drive 20 mph on the more local roads, as long as there are collector roads where you can go a bit faster.
