[clairity]

speed is a poor proxy metric for injury/death, but it’s mediopolitically expedient and as such used regularly to misdirect conversation and policy. to reduce injury/death, we need to address distracted driving, reckless driving, and impaired driving. notice that all of these share ‘inattention’ in common. also note that it’s very hard to legislate attention, which is why the conversation gets misdirected toward speed.

however, there are measures like narrowing car lanes, adding street trees, and installing bike lanes that have positive effect on attention by making collision dangers more obvious (without making them more likely). these measures tend to also lower speed, but lowering speed shouldn’t be the primary goal, lest we implement more ineffective measures like speed limits and speed humps rather than the effective ones.

[freemint]

How is total energy in crash a poor proxy? Yes there need to be confunding factors for a collision to happen but halving speed (and it being easier to loose speed at low speed) should more than half the energy that goes into breaking bones.

Yes there are interventions you can do to cut collision likelyhood by more than 75% but "poor proxy is unjustified".

[clairity]

the point is that speed doesn’t cause the accident, only makes it more severe. it doesn’t change casualty rates materially. what we want to reduce is the accident in the first place, and reducing speed doesn’t do that, only increasing driver attentiveness does that. once we better solve the attentiveness issue should we consider severity and speed’s contribution to it.