Go already

In order for everyone to just freaking go, their cars would have to be attached somehow.

I wonder if anyone's ever thought of linking a bunch of cars together so they can all stop and go simultaneously. And hey, since the cars are attached and all need to go to the same place, we can build a track instead of using high maintenance rubber on pavement and-

oop, we invented trains

I love re-deriving the train when people talk about autonomous cars/trucking and how they can already do the highway part easily
- What I dont fucking get is that even in Europe where even in shitty countries like Hungary and Slovakia we have train tracks that's about thousandfold what the US has, and we still put shit on Semis and have them drive between cities, cities that are all fucking connected by train.
  
  Why aren't we fucking putting everything on goddamn fucking trains, and then do only the last miles of the delivery on trucks, they could even be electric as that would eliminate all the drawbacks of electric semis, having them only go short distances
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!
Some sort of linked car-train lane that your car could use self-driving software to enter and leave would be an interesting concept. Like HOV but everyone is linked at the same speed.
- Interesting in concept i guess, but orders of magnitude less efficient than a train.
- This is trains but worse. The HOV lane also does not do much for traffic. It's slightly less miserable to sit through a traffic jam at times, but often is similar speed wise to a regular lane.
  
  Source: myself, driving in and around LA
And hey, since the cars are attached and all need to go to the same place

And voila, you just invented road networks again
- And this is the magical part where we recognize that both can exist
- the vast majority of people live in cities, where public transport demonstrably works just fine and is in fact necessary for them to not devolve into gridlock.

There is nothing more American than being in traffic. You're never more in touch with a systemic failure, yet we blame it on the choices of individual drivers, all the while unaware that we're part of the problem.

my man have you ever been in, like, another country?
- No, but they definitely don't have traffic in Germany. They have the Autobahn, the perfect solution to any and every traffic problem that could ever exist.
It's a little of column a and a little of column b. When I'm driving and some absolute piece of garbage is riding directly next to the car to their right, I equate them to a blood clot, which is funny, because they also make me feel like having an aneurysm. I also don't forgive the driver on the right, because they are more than capable of allowing a space for other drivers to pass.

The absolute lack of awareness on the road is startling. I swear to God, people are looking through straws and their neck doesn't move.

Building extra lanes, though, does not solve the problem.

Traffic dynamics are really interesting. Even after you clear the obstruction, the traffic jam remains and becomes a "ghost jam" that propagates backwards down the road until it eventually fizzles out.

Indeed - play with them here!

traffic-simulation.de
- I turned down politeness all the way and watched it become Dallas traffic almost immediately.
I agree, I think mythbusters did a small scale test in a circle.
- The Mythbusters also built a sweet plow truck that would get you through traffic.
It's like a pressure wave! The boat is gone, but the wake is still causing you problems.

Just ONE car can reduce traffic jams. Try it: leave enough buffer such that when the car in front of you stops, you almost reach their bumper at like 5 MPH but never stop b/c it’s time for them to move again. The guy behind you may never actually stop too.

So you had all these stoppers in front of you, and several cars not stopping behind you.

Enough people do this, and there’s no more stop & go. Just cruise 5mph the whole time (not 10, 0, 10, 0, 10, 0, which sucks).

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?
- Not sure what the problem is. Keep doing it.
  
  This is how I operate in most traffic jams, since I only own manual cars & it's much easier on my leg.
  
  I genuinely don't even remember any specific scenarios where somebody merging in caused me to have to come to a full stop (where I wouldn't have had to stop if they didn't merge). Not saying it never happened, but it was so rare and unnotable that I don't remember.
  
  I do live in the northeast US, so maybe that has something to do with it, but I don't usually feel like I spend meaningfully more time in traffic because I let a few people in front of me.
  
  Bonus benefit: my life is measurably better since I stopped getting pissed about people being in front of me. Road rage had such a broad impact on me, even after I got out of the car.
- Honest answer involves deep breaths (at least as one first adopts the method), chuckling at one’s favorite podcast, and recreating the buffer.
  
  On certain roads, monkey see monkey do and eventually folks behind you kinda copy you and there’s a chance fewer and fewer folks will be cutting you off. Notice this most on the longest trips. Perhaps they’re not copying you, btw, rather the most aggressive drivers continually pass you until a small cohort of Big Spacers remain behind you. If some of these Space-Not-Racers are in front and around you too, aggressive drivers passing are passing without cutting you off as much - they have enough space to jam themselves into the bumper of the car in front of you.
  
  Kinda funny going around a curve and seeing a hundred cars bumper to bumper ahead, then checking mirrors to see safe following distances :) (oh yeah this style is safer too not just more efficient!)
  
  Can require some SERIOUS brain hacking. How mad would we be if someone cut in front of us at the grocery store? We’d go butts2nuts in a blink. Gotta just, like, flowww mannnn
- I leave a gap between me and the driver in front of me. Rarely does anyone pull into that space. They usually are in the lane that gets them where they need to go
- sounds like you're no worse off, and now you've given things a chance to improve. Keep doing that and you still won't ever be worse off and eventually maybe that chance actually works and things get better.
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
- That's what it's for, for people to use. Let them, create new buffer. Let somebody else, create new buffer. There is exactly zero wrong with any of this.
- I concur. I used to be able to leave a huge gap and nobody would care. I drove a manual and didn't want the hassle of stopping. But, I tried this recently, and I ended up making the fast lane the slow lane and I had the guy behind me honking and yelling out his window to stop letting everyone in.
  
  Piss off the wrong guy in Texas and see where that gets you. I was lucky all he did was honk and yell.
- The weavers will go as easy as they came
- This happens to me too, often. But even so, there are some moments where they don't
Just one train can reduce traffic jams much more, imagine a bunch if them in different sizes, speeds and even underground some of them.
I learned this technique -- we called it "cutting off the head of the snake".

Traffic moves like water, and becoming fluid and just rolling sometimes can kill traffic completely, I was on a stretch of bright red (5-10 mph) that began moving at 55 MPH after patiently rolling -- there was no actual reason for the traffic jam.
Driving stick, I would do this all the time. In fact, I'd do it in the left lane, which I would never do, but for the fact all of the lanes are just constant stop and go. I'd leave massive buffers, 20-30 cars, and just cruise 5-10mph, and never stop. I just don't understand why anyone wants to use their brakes at all, I hate using my brakes. I'd rather just coast in perpetuity than feel inertia in any direction.
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
- https://youtu.be/ozG3EfPkXoY?si=iqdVjV92LvNz-cXC
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.
- Will ask the same of you as here :)
people who insist on going full speed and then SLAMMING their brakes drive me to drink, and this applies to literally all modes of transport.

If you're walking through a grocery store and are about to round a corner, fucking slow down so you have time to see anyone else coming your way, then you can speed up again when you know the coast is clear.

If you're driving a car and coming up to a red light, or even worse a pedestrian on a crossing, FUCKING SLOW DOWN and just coast slowly, it's not worth the off chance that you get to blast through at full speed, not for you or anyone else.
When I do this, I hear horns behind me, telling me to stick it into the car in the front, which is clearly stopped on a red light counting down from 20s.

It takes but an idiot. And 1/10 people on the road are idiots. So that's an idiot every 100m while commuting. There's no surprise.

At least 1/10 of them are idiots.
also, very respectfully to my mom and grandpa (RIP) old people have to stop driving. My mom is 65 and in pretty good shape so she refuses to stoo driving. She only have 2 road modes: Maniac or Tourtle. She'll alone create a standstill in a highway OR she'll almosr kill herself and everyone else on the road. No midle ground

You're not in traffic, you are traffic

Yeah but I'm trying to GO smoothly and courteously. Somewhere up ahead someone (or many someones) is stopping or merging badly or doing something else stupid to create these phantom traffic jams.

I've been watching traffic patterns for a while... Pretty much since I started driving.

I've wanted to answer the question of why does traffic get so bad sometimes?

The best analysis I can give from all of my observations is.... People SUCK at merging. They don't give space, they try to race to the "front" in lanes that are closing.... Nobody actually knows how to zipper merge properly.

Listen, there's basically two things you need to successfully zipper merge:

Find an opening where you can fit into
Match pace with the traffic you will be merging into.

For anyone in a lane that's being merged into: make space for merging traffic.

I know legally, that the driver entering the lane will have to find space to merge into, and the drivers in the lane where others are merging into, don't have a legal requirement to provide space, but by being a dickhead about it, you're actively choosing to make things worse for everyone. Just give some space. It's really not hard.

Everyone is more interested in getting somewhere fast, rather than doing things efficiently, in collaboration with fellow road users.... So, when someone inevitably gets cut off by someone who simply must be in front, and they have to slow down, it takes a lot of time for the impact from that showdown, to be recovered by traffic behind the offender.

But trying to re-educate millions, if not billions of drivers to not be horrible at merging, isn't something that's realistically going to happen.

Whenever you hear about "congestion" slowdowns, this seems to be the cause just about every time.

I can actively see this on some highways near me, they have an exit on one stretch of highway through a fairly large city, every mile. I can almost time it for when we get to an exit, vs when we get to an on-ramp, simply by when we slow down or speed up, exclusively due to this phenomenon.

Crashes and wrecks are a whole other issue. Between everyone being shit at merging, all the goddamned rubberneckers, and people making generally idiotic choices to change lanes when they have no idea what is going on..... We're fucked.

I don't hate traffic because it's slow. I hate traffic because it's entirely a product of people being stupid.

There's more to it than that - there's a lot of research involved. Other factors involve:

Nobody does anything at the exact same time.

What's a turn signal

I'm the main character!

Hold on my phone's ringing

I'm getting in front of you if it kills you!

Shit I'm gonna be 1 minute late for work!

Fuck you in particular!

One snowflake fell, time to panic!

ALL the snowflakes fell but who cares I've got 4wd!

Fuck this traffic, I'm taking the shoulder!

CRASH

Oh shit a cop everybody slow down.

And more!

Chief offender is the cascade effect. Basically, there is a minimum convenient distance one can follow another at a given speed in given conditions. If thee guy in front of them does anything but keep going, they should be able to deal with it without slamming on the brakes.

But if people follow more closely than that, especially because the traffic volume increases, then when car A slams on their breaks, so do cars B, C, D, E, etc. then because everyone's reaction speeds are marginally different, by the time you get to car F, everyone's come to a hard stop, while car A goes on, oblivious that they created a traffic jam that may or may not have been inevitable.
- I agree with the cascade effect, it's literally the reason why bad driving compounds into a traffic jam.
  
  The thing is, if you leave sufficient following distance, someone is going to take it as an invitation to merge, so people in general, wanting to be in front, tend to follow more closely, so nobody else can get in front of them and push them further back in traffic.
  
  So they follow too closely, someone brakes, and cascade of failure. Why they brake? Lots of stupid shit, often because someone entering the lane of traffic in front decided they're getting in front of someone else even if it kills everyone, then brakes, and cascade.... The cycle continues.
- Yea that cascade effect is huge. If everyone does what they're supposed to you really shouldn't need brakes on the highway much. Better to move continuously at a slow pace than tailgate and have to stop and go. It takes a second or two to actually move from a stop and that adds up over hundreds of cars when you add in the delay for everyone's reaction time.
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.
- Yep. The inability to understand how to merge correctly, IMO, goes hand in hand with being a bad driver.
  
  While merging is by far one of the most notable issues, it's certainly not the only one.
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.
- Anyone suggesting you should skip a light because you're on a bike, is not someone you want to listen to.
  
  Stay safe out there.
- 0 upvotes 0 down votes at time of writing. I agree with you, though.
Just wait for self driving cars. Once we get those all these bad drivers will fade into the crowd and the next thing you know you will be talking about "how bad drivers were" with some blinker refusing, 4mph under in the passing lane camping, stop in the middle of traffic to let someone pull out, jack wagon. You won't know they were a bad driver and they won't tell you they were.

We will be shoulder to shoulder with the scum of the earth and we won't even know it.

Drivers love their cars so much they will make traffic jams to spend more time in them.

The CGP Grey video on Traffic is a decent explainer on how traffic happens to begin with and how it gets relieved, kind of like a traffic snake that grows and shrinks, travelling in the direction opposite to traffic.

This City Nerd Video explains how traffic gets exponentially worse as it increases.

It usually starts with someone making a dumb move at a merge, changing lanes or another person forgetting to brake until the very last moment. That's part of the reason I don't see much benefit in adding more lanes to a highway save for very few exceptions, since you'll just have more changing lanes leading to slowdowns and extending a section that was a bottleneck often just shifts the bottleneck somewhere else.

So anyways, I'll keep preaching to the choir: trains, trains, we need more buses and trains.

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).
- You could carry a near infinite amount of cars on a highway if you could instantly accelerate to near the speed of light!
  
  In all seriousness, yes you're right that there is a max throughput of people per hour even with ideal drivers and cars on a given highway. You simply do not have enough space.
  
  The article was very interesting and informative, but that too assumes many ideal conditions. Re: zipper merging, the author really discounts the affect of confusion causing on cumulative delay. Of course that never letting anyone get in front of you, and decreasing your headway will theoretically let you get to your destination earlier, but you run the risk of needing to detour to an auto collision center. In a 2 to 1 merge, one of the lanes must delay themselves 2 more seconds, everybody playing chicken instead of sharing the delay across the two will cumulatively slow things down on the whole.
  
  This can also be accomplished with a traffic volume sensor and a stop light on highway on-ramps.
  
  This kind of traffic metering does already exist, as you're probably aware!
  
  But the fact that even just a single rail car holds 360 commuters, equivalent to 180 cars or more on the highway changes the math completely.
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
- Hey listen bud, I'm a massive advocate for trains and I think automated cars are an unrealistic idea in the near future.
  
  Still, you have to understand the origin of traffic to get a better understanding of how to come to a solution.
  
  "The solution to traffic is passenger trains" is a valid statement but is missing a lot of the intermediary as to how, why and completely skips the root causes of road traffic. That's why I put the CGP Grey video 1st since that's the first step, explaining traffic well even if I disagree with its conclusion, then CityNerd's video 2nd. After the 2nd, the conclusion that public transit would solve traffic because it reduces drastically car volumes should start to come naturally.

I will add serious distance to a journey in order to avoid a jam. I will wake at an inhumane hour to avoid traffic. I know it's irrational but sitting in traffic is the worst. My life was so easy when I cycled to work. Literally zero traffic jams for twelve years. Every journey to and from home was fifteen minutes.

Same I moved to a place that lets me take mostly side roads to get in to work and I'm loving it. It is about 10 minutes longer than the highway if everything is perfect but if you account delays caused by traffic its usually almost even or faster if there's a bad accident or something.

they keep switching lanes

How is standing in traffic a real thing? Mfer just pass everyone on your bike!

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

They have to get up to speed and there are so many on ramps that don't give enough space to actually get up to highway speeds. And some places (like my fucking dumbass city) have 30 of them spaced only 10 feet apart, so you have a lot of people going really slow getting on the freeway, so everyone else has to slow or stop to avoid hitting them.

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.
- I'd never heard that point and it's really interesting. I drive around the part of NJ that is close to NY, Bergen, Essex, Hudson Counties, and sometimes it's a straight up stop sign at the edge of a highway. And the problem is, there's no other way to go, I'm not cutting through a residential area or nothing, this is me coming from the turnpike onto Rt. 9 or something, massive thoroughfares with insane volumes. And you just do commit and that's it. Terrible design, but with the light you've shown on it, I can understand it a bit better.
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
- There's actually a good bus system here. But it's literally the city in American Graffiti so the first part is accurate.

I feel like HOV lanes are more trouble than they’re worth because they disrupt traffic flow since people need to slow down when the HOV drivers enter/exit