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Make it make sense

Scheduled Pinned Locked Moved Lemmy Shitpost
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  • I [email protected]

    Too many people were taught, and still teach, the "two car's length" rule. Which is awful. 2 to 3 seconds is much better and intuitive to figure out.

    You say 3, which is great, but I'd settle for 2. Most people on the highways around me leave more like 0.5; I sincerely think the vast majority of people greatly overestimate the amount of space in front of them to the next car.

    merc@sh.itjust.worksM This user is from outside of this forum
    merc@sh.itjust.worksM This user is from outside of this forum
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    wrote last edited by [email protected]
    #81

    Two car lengths is ridiculously close. The average car is approx. 4.5m in length. Two car lengths is 9m. The average human reaction speed to visual stimuli is approx 250 milliseconds. At 100 km/h (28 m/s) you would travel 7 metres in that time, and that's just the time for you to notice the stimulus and react, not to choose an appropriate action. If you're 2 car lengths behind and the car in front of you brakes hard, you're going to hit it.

    2 seconds behind is 56 metres behind, or 12.5 car lengths. 3 seconds is 18.5 car lengths. Even 0.5 seconds is 3 car lengths. Not enough to safely react to the car in front of you doing something unexpected, but not the tailgating that 2 car lengths implies.

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    • T [email protected]

      It's the people not zipper merging correctly. You have idiots entering that are not up to speed and you have idiots breaking for the idiots not up to speed.

      On ramps should be required to have their lane not end abruptly which causes the panic. The on ram should continue for at least a 1/4 mile.

      merc@sh.itjust.worksM This user is from outside of this forum
      merc@sh.itjust.worksM This user is from outside of this forum
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      wrote last edited by
      #82

      idiots breaking

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      0
      • B [email protected]

        CGP grey did a video on it: https://www.youtube.com/watch?v=iHzzSao6ypE

        Basically one car breaking too much will make the following brake even more and so on until one stops and there's a jam. There is no clear reason like a road blockage or an accident, just compounding slow down.

        merc@sh.itjust.worksM This user is from outside of this forum
        merc@sh.itjust.worksM This user is from outside of this forum
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        wrote last edited by
        #83

        Basically one car breaking too much will make the following brake

        If the car in front of me started breaking, I'd definitely get out of the way.

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        • stamets@lemmy.worldS [email protected]

          Only ever have to ask, my friend

          Heres an overview shot of a traffic pulse.

          One person brakes for no reason which leads to everyone else braking. The pulse travels despite there being nothing there. The longer it can take for someone to start up again also can delay the whole thing.

          J This user is from outside of this forum
          J This user is from outside of this forum
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          wrote last edited by
          #84

          Nope that's just a negative picture of a guy

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          3
          • K [email protected]

            So, I don't know exactly how the adaptive cruise control works. But if it is slowing down and speeding up to maintain a specific distance, that does not fix things. The idea is to maintain a specific speed such that, as the people in front of you accelerate and brake, speed up and slow down, you have enough distance to not have to do that. You should essentially match their average speed with enough gap that their braking doesn't put them close enough to your bumper that you have to slow down yourself. Normal cruise control would be better (except mine won't set at speeds under, I think, 20mph) because your speed wont change. Adaptive cruise would make your drive safer, maybe, keeping you from being too close or failing to react to the change in traffic speeds, but I dont think it would solve the traffic issue itself.

            A This user is from outside of this forum
            A This user is from outside of this forum
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            wrote last edited by
            #85

            You aren't solving traffic as an individual driver anyway. Sorry to burst everyone's atomized bubble here but that's complete nonsense.

            If you manually maintain a large gap in front of you, everyone behind you becomes complete weirdos.

            We could "solve traffic" by not requiring single occupant car drives to accomplish everything in our daily lives.

            D 1 Reply Last reply
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            • merc@sh.itjust.worksM [email protected]

              If you're in traffic (i.e. if you are part of the traffic) and you leave a 3 second gap between you and the car in front of you, another car will drive into that gap. If you back off to create another 3 second gap, it will happen again. Even worse, if you hit the brakes to create that three second gap, even if it's very lightly, you might cause an even worse traffic jam behind you.

              I would prefer to leave a big gap to the traffic in front of me, but in many cases 3 seconds simply isn't practical. A car merging into the lane in front of you is inherently more dangerous than a car already being in that lane. If you keep trying to maintain a 3 second gap in heavy traffic, not only do you put yourself in more danger as you keep having cars merging in front of you, you also cause more danger to the drivers behind you by constantly backing off or braking to try to maintain a gap.

              It would be absolutely wonderful if everybody believed in the 3 second rule. Traffic would flow so much more smoothly. But, apparently that isn't human nature. And, if you keep fighting for that gap when nobody else believes in it, you can actually make things less safe for yourself and for others.

              rhaedas@fedia.ioR This user is from outside of this forum
              rhaedas@fedia.ioR This user is from outside of this forum
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              wrote last edited by
              #86

              If you're still moving with traffic, why do you care that someone got in front of you? If you're slowing so much that lots of people are getting in front at one time, then you're the obstacle. A 3 second gap changes with speed, if it's slow traffic that's less than a car length. And if some asshole muscles their way into a gap unsafely, let them. You'll still get to your destination far faster than if you hit each other or cause some road rage stupidity because of who is in front.

              Driving brings out the worst in people for no gain at all.

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              • the_picard_maneuver@piefed.worldT [email protected]
                This post did not contain any content.
                G This user is from outside of this forum
                G This user is from outside of this forum
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                wrote last edited by
                #87

                https://www.mdpi.com/2076-3417/11/9/4278

                TLDR: modeling traffic as a gas leads to fairly accurate predictions. If that doesnt mean anything to you, here's a decent visualization of how gasses move around in a system. In this analogy, each of the gas particles models a car on the road. https://youtu.be/Hr5Baj3lXFA

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                • the_picard_maneuver@piefed.worldT [email protected]
                  This post did not contain any content.
                  ithinkdifferentthanu@lemmy.worldI This user is from outside of this forum
                  ithinkdifferentthanu@lemmy.worldI This user is from outside of this forum
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                  wrote last edited by [email protected]
                  #88

                  slow speeds cause accidents, not speed, it it the sudden stop, the cause of some inbred driver

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                  • O This user is from outside of this forum
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                    wrote last edited by
                    #89

                    I don't always hang out behind a semi when just doing daily driving, but I will 100% camp out behind one when pulling my trailer - massive fuel savings from reduced wind resistance.

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                    • merc@sh.itjust.worksM [email protected]

                      If you're in traffic (i.e. if you are part of the traffic) and you leave a 3 second gap between you and the car in front of you, another car will drive into that gap. If you back off to create another 3 second gap, it will happen again. Even worse, if you hit the brakes to create that three second gap, even if it's very lightly, you might cause an even worse traffic jam behind you.

                      I would prefer to leave a big gap to the traffic in front of me, but in many cases 3 seconds simply isn't practical. A car merging into the lane in front of you is inherently more dangerous than a car already being in that lane. If you keep trying to maintain a 3 second gap in heavy traffic, not only do you put yourself in more danger as you keep having cars merging in front of you, you also cause more danger to the drivers behind you by constantly backing off or braking to try to maintain a gap.

                      It would be absolutely wonderful if everybody believed in the 3 second rule. Traffic would flow so much more smoothly. But, apparently that isn't human nature. And, if you keep fighting for that gap when nobody else believes in it, you can actually make things less safe for yourself and for others.

                      I This user is from outside of this forum
                      I This user is from outside of this forum
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                      wrote last edited by
                      #90

                      "if you leave a 3 second gap, there will be enough space for others to safely merge into that space as they need to"

                      merc@sh.itjust.worksM 1 Reply Last reply
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                      • S [email protected]

                        3 fucking seconds

                        The answer is a simple 3 second gap.

                        That's it, just 3-mississippi (or 3-onethousand) seconds behind the car in front of you and most of the avoidable jams go away.

                        C This user is from outside of this forum
                        C This user is from outside of this forum
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                        wrote last edited by
                        #91

                        Except the person next to you or behind you gets frustrated and cuts you off and you have to hit the brakes and create a traffic pulse.

                        S 1 Reply Last reply
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                        • S [email protected]

                          3 fucking seconds

                          The answer is a simple 3 second gap.

                          That's it, just 3-mississippi (or 3-onethousand) seconds behind the car in front of you and most of the avoidable jams go away.

                          merc@sh.itjust.worksM This user is from outside of this forum
                          merc@sh.itjust.worksM This user is from outside of this forum
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                          wrote last edited by
                          #92

                          If you do that, someone will move into the gap. If someone moves into the gap you can slow down to make another gap to them, but then someone else will drive into that gap. I don't know of any major city where you can maintain a 3 second gap during rush hour.

                          Even worse, if you ever brake to try to create a gap, you're likely to cause a traffic jam behind you.

                          Sure, if everybody did follow the suggestion and allowed a 3 second gap you wouldn't have traffic jams, but that's just not human nature, apparently.

                          N P S 3 Replies Last reply
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                          • C [email protected]

                            Except the person next to you or behind you gets frustrated and cuts you off and you have to hit the brakes and create a traffic pulse.

                            S This user is from outside of this forum
                            S This user is from outside of this forum
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                            wrote last edited by
                            #93

                            Well yes, society functions only with cooperation. Uncivil behaviour ends with violence and dismay.

                            However 3s usually allows for slow adjustments which alleviate caterpillaring.

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                            • I [email protected]

                              People changing lanes

                              If everyone stuck to the driving lane and only moved over to pass one car in front of them then there’d be less.

                              merc@sh.itjust.worksM This user is from outside of this forum
                              merc@sh.itjust.worksM This user is from outside of this forum
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                              wrote last edited by
                              #94

                              Which one of these is the "driving lane"?

                              A highway in LA

                              I 1 Reply Last reply
                              0
                              • I [email protected]

                                "if you leave a 3 second gap, there will be enough space for others to safely merge into that space as they need to"

                                merc@sh.itjust.worksM This user is from outside of this forum
                                merc@sh.itjust.worksM This user is from outside of this forum
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                                wrote last edited by
                                #95

                                And after they do, there will no longer be a 3 second gap, and you're now driving too close to the person in front of you.

                                9 1 Reply Last reply
                                0
                                • K [email protected]

                                  So, I don't know exactly how the adaptive cruise control works. But if it is slowing down and speeding up to maintain a specific distance, that does not fix things. The idea is to maintain a specific speed such that, as the people in front of you accelerate and brake, speed up and slow down, you have enough distance to not have to do that. You should essentially match their average speed with enough gap that their braking doesn't put them close enough to your bumper that you have to slow down yourself. Normal cruise control would be better (except mine won't set at speeds under, I think, 20mph) because your speed wont change. Adaptive cruise would make your drive safer, maybe, keeping you from being too close or failing to react to the change in traffic speeds, but I dont think it would solve the traffic issue itself.

                                  O This user is from outside of this forum
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                                  wrote last edited by
                                  #96

                                  It's not "locked" to a specific distance, it's fairly elastic and the exact follow distance varies based on speed. So, if traffic slows down, it will gradually close the gap while also slowing down. The end result then is far less drastic speed changes.

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                                  • merc@sh.itjust.worksM This user is from outside of this forum
                                    merc@sh.itjust.worksM This user is from outside of this forum
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                                    wrote last edited by
                                    #97

                                    If you're still moving with traffic, why do you care that someone got in front of you?

                                    Because you no longer have a 3 second gap so you can no longer safely react to something happening in front of you.

                                    If you're slowing so much that lots of people are getting in front at one time, then you're the obstacle.

                                    That's my point. If you keep trying to make a 3 second gap and it keeps being filled in, you're going to cause a traffic problem.

                                    A 3 second gap changes with speed, if it's slow traffic that's less than a car length

                                    Technically, sure. If you're driving at less than 5 km/h and people on foot are passing you, then yes, you can have a 3 second gap with less than 1 car length. But, if you're driving at less than 5 km/h are you really driving, or are you effectively stopped in traffic?

                                    9 1 Reply Last reply
                                    0
                                    • E [email protected]

                                      This is the correct answer. There isn't a city on earth that has fixed congestion by building for more cars. It's the places that build for trains and bikes that are best for driving, ironically.

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                                      wrote last edited by
                                      #98

                                      Sometimes, you achieve good traffic flow by making a city so absurdly difficult to drive in that people give up, park in the outskirts, and take public transport.

                                      Example: Amsterdam. In the city, there is almost no traffic, achieved through insanely twisty road signals, stupid expensive parking spots and no gas stations. And still, almost no traffic doesn’t mean no traffic… I can’t understand people still clinging to a car in such conditions.

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                                      • agamemnonymous@sh.itjust.worksA This user is from outside of this forum
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                                        wrote last edited by
                                        #99

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                                        • merc@sh.itjust.worksM [email protected]

                                          And after they do, there will no longer be a 3 second gap, and you're now driving too close to the person in front of you.

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                                          wrote last edited by
                                          #100

                                          You don't have to brake and maintain a hard 3 seconds between gap. Just let off the gas a bit let it slowly restore itself. That gap is there so cars can move in and out as freely as they need.

                                          merc@sh.itjust.worksM 1 Reply Last reply
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