I love re-deriving the train when people talk about autonomous cars/trucking and how they can already do the highway part easily

And instead of each one having a small engine, we could combine it all into a big one more efficient than separate ones would be!

my man have you ever been in, like, another country?

Indeed - play with them here!

traffic-simulation.de

I agree, I think mythbusters did a small scale test in a circle.

Tried it. Now I'm stopped bumper to bumper with the guy who cut me off to cram his truck into the buffer I left. What's the next step?

If I leave any kind of gap between me and the car in front, it is an inevitability that some jackass will swoop in to cut me off. Happened 7 or 8 times just yesterday. Texas drivers are a menace

Just one train can reduce traffic jams much more, imagine a bunch if them in different sizes, speeds and even underground some of them.

All it takes is one guy behind you checking his phone, getting distracted so he gets cut up to create another stop start system about 5 cars back.

You're vision of the traffic jam is a fragment of the entire pie.

From above the whole thing looks like an accordion. Drivers who tailgate tend to overreact when they see brake lights 50 feet in front of them, compound this by the guy tailgating them and so on. Leave a buffer to absorb this and it smooths out

I've had the same fascination!

A video I really enjoyed was a simplified experiment where they had some cars drive around in a closed loop - a single lane circle.

Traffic jams still inevitably somehow popped up, suggesting that we're simply bad drivers haha. Higher level autonomous cars cannot come fast enough.

It becomes much harder to zipper merge, when there is a red light ~500m ahead and said 500m is almost full.

I also hate it when I am waiting at a red light and someone nearby suggests me to just skip the light, because I won't get a fine (bicycle). I feel like people taking a test for the license (and renewing their license) should be reminded that the reason traffic laws exist is to prevent traffic jams and accidents.

While things like merging movements and so on is part of the story, it's not the whole story.

You see, by saying "traffic jams are caused by merging mistakes and so on" it kinda implies that if everyone drove perfectly a highway lane could carry infinitely many cars. In actually a highway lane has a finite capacity determined by the length of the vehicles traveling on it, the length of the gap between them (indirectly determined by how fast they can start and stop), and the speed they're moving.

There are finite limits for gap widths and speed determined by physics and geometry. As the system approaches these limits it becomes less and less able to deal with small disruptions. In other words, as more cars move on a freeway a traffic jam becomes more and more likely. The small disruption which is perceived as the cause was really just the nucleation point for a phase change that the system was already poised to transition through. If it wasn't that event then something else would trigger it.

It is interesting to note that once a highway has transitioned from smooth flow to traffic jam its capacity is massively reduced, which you can see in the graphs in the above link. Another interesting thing to note is that the speed vs volume graph, if you flip it upside down, resembles a cost / demand curve from economics, where volume is the demand and time spent commuting (the inverse of speed) is cost. If you do this you see something quite odd, which is that the curve curls up around itself and goes backwards.

This is less like a normal economic situation (the more people use a resource the more they have to pay, the less people use it the less they have to pay) and more like a massively multiplayer version of the prisoner's dilemma. For awhile the cost increases only slightly with growing demand, until a certain threshold where each additional actor making a transaction has a chance to massively increase the cost for everyone, even if consumption is reduced. Actors can choose to voluntarily pay a higher time cost (wait before getting on the freeway) to avoid this, but again, it's the prisoners dilemma. People can just go, trigger a traffic jam anyway, and you'll still have to sit through it + all the time you waited trying to prevent it.

Self driving cars are often described as a way to eliminate traffic jams, but they don't change this fundamental property of how roadways work. It's true that capacity could potentially be increased somewhat by decreasing the gap between cars, since machines have faster reflexes than humans (though I'm skeptical of how much the gap can really be decreased; is every car going to weigh the same at all times? Is every car going to have tires and brakes in identical conditions? Is the condition of the asphalt going to be identical at all times and across every part of the roadway? All of these things imply a great deal of variability in stopping distance, which implies a wide safety gap.), but the prisoner's dilemma problem remains. The biggest thing that self driving cars could actually do to alleviate traffic jams would be to not enter a highway until traffic volumes were at a safe level. This can also be accomplished with a traffic volume sensor and a stop light on highway on-ramps.

Of course trains, on top of having a way higher capacity than a highway lane, don't suffer from any of this prisoner's dilemma stuff. If a train car is full and you have to wait for the next one that's equivalent to being stopped at a highway on ramp. People can't force their way into a train and make it run slower for everyone (well, unless they do something really crazy like stand in the door and stop the train from leaving).

https://youtu.be/oafm733nI6U?si=dUBMco9Ql-QtLF2a

Broke: thinking cgp greys video is informative and good

Woke: realizing cgo greys video is fucking stupid and car brained

Me, in an empty bus, standing with people who could just sit in the bus with me so the street would be empty

Quite a few cities in the Northeast are designed this way, because they were done so in the 1950' swith the intent of highway traffic doing 40, maybe 45 MPH through town at maximum. To conserve expensive urban land, they have short ramps and merge areas that were appropriate for those speeds, not to mention the lower overall volume of traffic in those times. And now we're stuck with it, because it'll be a 200 year long court battle to eminent domain the 427 landowners who are all clinging to five square feet each in the patch you'd require for a longer ramp, all hoping for a fat payout to let go of it.

And nowadays, of course, everyone takes it as their god given right to do 90+ MPH on the freeway at all times, and get frothingly pissed off if they can't for any reason whatsoever. So the ramps aren't long enough anymore because no one is using the highway as designed.

You live in a shitty car centric designed city with poor public transportation.

Ftfy, fucking suburban shit ass sprawl is even spreading to my country like a plague, fuck that shit