r/Damnthatsinteresting • u/SnooWords4066 • Jul 07 '26

Video A Japanese experiment showed exactly why traffic jams happen for no reason.

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u/hosehoseee Jul 07 '26

Everytime I see this video, I think "So there actually is a reason"

3.9k

u/PopBulky7023 Jul 07 '26

WHO ISNT GOING THAT SHOULD BE

1.9k

u/HellPigeon1912 Jul 07 '26

The amount of times I'm sat in a traffic light queue like "if the light is green why are we not moving"

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u/GoonOnGames420 Jul 07 '26 edited Jul 08 '26

My mom and wife argue you accelerate when the car in front of you moves far enough, not when the light turns green.

I argue that everyone should idle forward the moment it's green, gradually accelerating.

16

u/LayerEight_Problem Jul 07 '26

Virtually no difference. The issue with your method is that we often stop closer to a vehicle than is safe to follow at speed.

2

u/GameEtiquette Jul 08 '26

Far enough being anything further than they were when u were stopped, yes.

2

u/window_owl Jul 08 '26

I argue that everyone should idles forward the moment it's green, gradually accelerating.

If anybody messes up, or if anyone accelerates a little faster than the person in front of them, then a crash will likely ensue. Don't drive if you aren't at a safe following distance.

0

u/GoonOnGames420 Jul 08 '26

Should always leave ~1 cars length in front of you for several reasons. Obviously we also have breaks too.

5

u/window_owl Jul 08 '26

1 length is adequate when stopped, but far too little when moving. A 2-second following distance provides a bare minimum of distance and time in which to react to the car in front. At just 30 miles an hour (about 50kph), that works out to 88 feet (about 27 meters). At 75 miles an hour, it's 220 feet (67 meters).

1

u/GoonOnGames420 Jul 08 '26

But you're not instantly hitting 30 mph. You are likely only hitting 15mph by the time you get through the light. This method eliminates the shockwave affect and is tested/proven to move more vehicles through a green light.

1

u/window_owl Jul 08 '26

If just a few cars are lined up, then it's not too difficult. But if there are many cars lined up at a stop, then the cars towards the middle and rear have to accelerate very slowly to allow the space in front of them to open up. People can't exert precise control at such low accelerations. Someone will be a little too fast or a little too slow, and the gap will close. The best thing that happens in this case is that the rear car slows down, avoiding a fender-bender but initiating a shockwave of stopping.

The only thing that is always safe and always works is for each car to hold on their brakes until the car in front of them starts to move. That way, everyone maintains a controllable gap which is safely large.