12mo ago

Speed vs Fatality Infographic

26 comments

So it's best to always be the last pedestrian in the line. OK, got it.
Last time I heard about it it was 50-60% fatality at 50km/h, but only 3% at 30km/h.
Maybe depends on which country the data comes from.
Anyway, 30km/h in the city is a given.
- Also gonna depend on the car. The oversized lifted truck is gonna kill more reliably than a mid sized sedan
  
  I think the info was from sweden, maybe volvos are more cushiony :-)
- The country also factors into it because inertia depends on weight and increases exponentially by speed so if there are more trucks and SUVs, that rate goes up rapidly. The average car size also increases YOY, so it's continually getting more fatal to be hit by a car.
What version of the trolley problem is this
- Two tracks, one with 50 people tied where the switch is currently set, and the other with somewhere between 0 and 5 people tied. You could switch the trolley to the other track...
  ...but the trolley passengers would be upset at you because they'd be 4 minutes later to work every day. Oh no.
30 km/h is 8.3 m/s, are you implying the driver reaction time is 2.5s? Or is this chart for mentally challenged drivers?
- I'm trying to figure this out too. Those distances seem really suspicious. At 30km/h, I'm pretty sure I can stop my (admittedly small) car in less than 1 car length. Maybe half a car length, something like 2m? Way less than 9m.
  
  And looking at 60km/h, that's 17m/s and they are claiming a 43m stopping distance. That would be like hitting the breaks and your car just slides on the pavement for 2.5 seconds, traveling the distance of an Olympic swimming pool, before stopping. That's only reasonable in the worst possible driving conditions. Or maybe with an enormous and heavily loaded vehicle?
  Or maybe I'm being too optimistic here? Maybe these are numbers from actual accidents and in real life people hit the break slowly at first and stuff like that?
  
  Sure, if someone says 3-2-1 brake and you're expecting a test. But that's now how people react while driving every day.
- Yep. 2.5s is the average perception reaction time. This includes
  Perceiving the person
  Understanding the situation and thinking about whether you need to stop
  Moving your foot to the brake pedal
  Keep in mind, most people feel comfortable driving and not expecting to have to make an emergency stop at all times. Sure, you'd be ninja-fast if you were in some test environment where you expected the hazard and were trigger happy on the brake but that's not the real world.
  A few US states, including California, have adopted a standard driver reaction time of 2.5 seconds. The United Kingdom's Highway Code and the Association of Chief Police Officers ACPO Code of Practice for Operational Use of Road Policing Enforcement Technology use 3.0 seconds for driver reaction time.
its interesting how the change is so dramatic between 40 and 50, compared to the other values, I wonder why that is
- Quite likely where the limit of the sturdiness of bones and organs lies. It's not unreasonable to have a point where important parts fail no matter how you are hit or land, below which it's more unlucky hits that do damage to specific parts of your body that cause death.
- iirc kinetic energy is [edit: half] mass times velocity squared, so the energy increases much faster than the velocity above a threshold
  
  That's correct!
Need to have Freedom Units conversion for thw US
- 10 km is a little over 6 miles
  1m is basically a yard, or 3ish feet.
  If you're using non-metric forms of measurement, I assume that "close enough" is the goal.
  
  Yes, you are technically correct, the best kind of correct...but how many bald eagles per football field is it?
- 30 km/h = 328 football fields per MLB pre-game warmup
It's too bad that drivers ignore those speed limits and drive fast enough to give no chance of survival.
- Yeah... It's a limit, not a minimum.

26 comments