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.
> At the point where a 30km/h car would have come to a stop, a 50km/h car still impacts with 30km/h.
At that point it's barely superlinear. That means instead of dropping by 30kph it dropped 20kph.
Personally I'd focus more on how even a linear increase in stopping distance is a problem when pedestrians are around.
> 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.
Negligible speed impact also means negligible safety impact.
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.