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.
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?
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.
But similarly, human behavior can be trained. We aren’t NPCs. These bad drivers could be taught to drive at a safe speed regardless of the width of the street, through stricter education and enforcement. Pedestrians/cyclists/homes/businesses around the street -> drive slow, that should be an instinct.
Enforcement doesn’t work for what I’m describing, without conscious effort, humans drift to the speed they think they need. Always. So whenever you try to policy it, you are asking folks to go against their nature.
Change the shape / characteristics of the road to change the speed people drive it.
As I said, I completely agree that changing the shape of the road is an important component of this solution.
Yes, I am asking the operators of deadly heavy machinery to put in a small amount of conscious effort to keep people safe. Why is that an impossible request?
No one in my state complies with the speed limits because they’re ridiculously low for the design of the road. You have a road built to handle 90mph but you tell people to go 30mph? Yeah that ain’t happening
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.
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.
The fact that you talk like you have enough samples to make that inference worries me.
Sounds like this guy needs to stop driving into parked cars.
He only hits people in the lots, not cars. So it’s fine.
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?
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.
Not excusing shit, I’m describing human behavior. Humans literally drift to the speed they think is right, by feel.
Don’t assume intent.
But similarly, human behavior can be trained. We aren’t NPCs. These bad drivers could be taught to drive at a safe speed regardless of the width of the street, through stricter education and enforcement. Pedestrians/cyclists/homes/businesses around the street -> drive slow, that should be an instinct.
I said “change the actual road”
Enforcement doesn’t work for what I’m describing, without conscious effort, humans drift to the speed they think they need. Always. So whenever you try to policy it, you are asking folks to go against their nature.
Change the shape / characteristics of the road to change the speed people drive it.
As I said, I completely agree that changing the shape of the road is an important component of this solution.
Yes, I am asking the operators of deadly heavy machinery to put in a small amount of conscious effort to keep people safe. Why is that an impossible request?
No one in my state complies with the speed limits because they’re ridiculously low for the design of the road. You have a road built to handle 90mph but you tell people to go 30mph? Yeah that ain’t happening
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.