• Valmond@lemmy.world
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    3 months ago

    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.

    • Rentlar@lemmy.ca
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      3 months ago

      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.

  • Coconut1233@lemmy.world
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    3 months ago

    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?

    • myfavouritename@lemmy.world
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      3 months ago

      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.

      • myfavouritename@lemmy.world
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        3 months ago

        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?

        • myfavouritename@lemmy.world
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          3 months ago

          I get that my performance will change depending on whether I’m expecting a test or not. But I think if my car has its breaks slammed, it’s going to stop in less than 9m starting at 30km/h, regardless of whether it’s expecting it or not. It’s the stopping distance that I’m feeling is larger than it should be.

          A couple questions. Is the stopping distance in this diagram the distance the car travels after the driver has completed their reaction time and started hitting the breaks? And where does the value from this distance come from?

          I wouldn’t have thought to ask you before. A lot of times people just post things they find online that impact them in some way. But you seem to have a lot of knowledge that goes beyond just seeing this image.

          And, anecdotally, I was driving late last night and an animal jumped out into the road ahead of me. I would like to avoid hitting an animal just as much as hitting a person. But I didn’t immediately slam on my breaks to stop the car as quickly as possible. I gradually squeezed that break pedal until I was rapidly slowing. So maybe my assumption about stopping distance is wrong. Maybe the car can stop faster, but when driven by average people it doesn’t, simply because average drivers don’t stop optimally.

    • 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.

  • Showroom7561@lemmy.ca
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    3 months ago

    It’s too bad that drivers ignore those speed limits and drive fast enough to give no chance of survival.

    • DerisionConsulting@lemmy.ca
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      3 months ago

      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.

      • Che Banana@beehaw.org
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        3 months ago

        Yes, you are technically correct, the best kind of correct…but how many bald eagles per football field is it?

        • DerisionConsulting@lemmy.ca
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          3 months ago

          I love the ambiguity of the question! So many variables in such a small amount of room!

          Are we talking area, or end to end, or side to side, or diagonal?
          Bald eagles: adult, or immature? Male, or female? Footprint, or height, or wingspan length, or volume (in case we are painting the field, maybe we’re just painting the lines on the field with bald eagle goo??), or maybe we’re covering the field with their feathers?
          It probably isn’t a kicking-football pitch because it isn’t really called a field, so are we talking throwing-football, CFL? NFL? another league I am not familiar with?

          I am genuinely tickled, and quite content to never being able to answer the question

          • Che Banana@beehaw.org
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            3 months ago

            Well, in freedom units it is a bald eagle, and an NFL football field.
            I would imagine its wingspan per cheeseburger, and when counting the small lengths we need to convert to bullets (which ironically goes back to metric; 50mm, 35mm, 9mm etc.)

            I would also assume we are talking about length because that is the main topic (or was, I should say), and we don’t want to confuse with liquids or weight.