One Driver Can Prevent a Traffic Jam

[cpzilliacus]

[WSJ.com is a paywalled site.  If you cannot read this in full, leave me a PM with a real e-mail address and I will send you a link.]

WSJ.COM: One Driver Can Prevent a Traffic Jam - With congestion getting worse, proponents advise techniques, such as preventing bottlenecks, letting others cut in; the problem with tailgaters

When you're caught in a traffic jam, you feel powerless. What you may not know is that you can actually have a big effect on the traffic around you.

There is a growing body of research finding that an individual driver, by preventing bottlenecks and maintaining a steady speed, can sometimes single-handedly ease or break up a traffic jam.

The techniques are simple, though some of them–such as leaving a large gap between your car and the one in front and freely letting other drivers cut in–feel counterintuitive to most drivers.

[Brandon]

Yeah, I know this works from personal experience.  I leave a gap and merely go up and down a bit in speed rather than speeding up and hitting the brake.  The line of cars behind me usually appreciates it.

[jeffandnicole]

If the car in front of you is hitting the brakes and you're not, then that actually disproves this guy's whole theory! 

[empirestate]

Well sure, that's a no-brainer. If there's traffic ahead of you and you zoom up as fast as you can, all that happens is you arrive at the traffic sooner.


iPhone

[ET21]

SCIENCE

COMMON SENSE!

[jakeroot]

It's really tough. I want to leave a big gap (easier with a stick), but people just keep filling whatever gap develops. Then people behind you become cross because of how many cars you're letting in. Meanwhile, you're getting farther and farther back, compared to where you would have been, had you not left the gap --- ugh.

At this point, I think people realize that sudden braking causes chain reaction slowdowns. But there's simply no way to avoid it, without full-scale AI intervention at least.

[Pete from Boston]

It's really tough. I want to leave a big gap (easier with a stick), but people just keep filling whatever gap develops. Then people behind you become cross because of how many cars you're letting in. Meanwhile, you're getting farther and farther back, compared to where you would have been, had you not left the gap --- ugh.

At this point, I think people realize that sudden braking causes chain reaction slowdowns. But there's simply no way to avoid it, without full-scale AI intervention at least.

There is one way I know to deal with this — don't get too upset about people cutting in front of you, don't get too upset about slowing down people behind you. All you really need to worry about is maintaining a safe distance and driving at a speed that avoids sudden braking.

I deal with it every morning and afternoon.  There's no real answer, so you (literally) roll with it.

[Ga293]

There's a great CGP Grey video recently released about this very topic that discusses these tactics.

Spoiler alert: one driver can ease a jam a little bit, but they can't prevent it. One driver can cause one though.

[kalvado]

 I think this one really sums up everything

[SP Cook]

I normally like CGP Grey's works a lot.  He is obviously a thoughtful person.  This video doesn't add to his reputation.  What he esentually advocates is self-driving cars with the micro-second tolerances for filling and clearing space. 

Every broke a timing belt?  Same issue, except instead of blowing a motor, you kill a couple dozen people.  Which is why all of this self-driving nonsense is, well, nonsense. 

As to the WSJ article, the economists at WSJ would call this the "free good problem".  Yes, what they advocate would work.  If everybody did it.  As would practicing simple lane courtesy.  Lack of lane courtesy is the basic cause of most traffic jams, most freeway accidents, and most road rage. 

Keep right, except to pass.

[kalvado]

Every broke a timing belt?  Same issue, except instead of blowing a motor, you kill a couple dozen people.  Which is why all of this self-driving nonsense is, well, nonsense. 

One thing about reduced separation - collision would occur at much lower relative speed - previous car wouldn't slow down that much before arrival of next car. Which means lower accelerations with cabin, less traumatic outcome for humans.

As for dense driving of automatic vehicles.. I would be more concerned about minimum guaranteed performance of cars - in order to achieve accident-free flow everyone must be able to break like everyone else does. That pretty much means technical - not legal - limits on tire performance, pads operation, sensor conditions etc. May be easier to say than implement and enforce.

[empirestate]

It's really tough. I want to leave a big gap (easier with a stick), but people just keep filling whatever gap develops. Then people behind you become cross because of how many cars you're letting in. Meanwhile, you're getting farther and farther back, compared to where you would have been, had you not left the gap --- ugh.

Right, well the idea is that you're supposed to not be concerned with where you are in the line. Once everyone is doing the system correctly, that issue would largely disappear anyhow.

Indeed, the reason we don't enjoy this system already is that everyone on the road is better than everyone else at being faster than everyone else.



iPhone

[Duke87]

I normally like CGP Grey's works a lot.  He is obviously a thoughtful person.  This video doesn't add to his reputation.  What he esentually advocates is self-driving cars with the micro-second tolerances for filling and clearing space. 

Every broke a timing belt?  Same issue, except instead of blowing a motor, you kill a couple dozen people.  Which is why all of this self-driving nonsense is, well, nonsense.

Also, even in a world where all cars are automated, bikes and peds won't be. And neither will deer (or chickens). Or the presence of ice. Or...

The sort of unsignalized intersection depicted in the video where all vehicles coordinate seamlessly with extremely close tolerances would be achievable in laboratory settings but is not something we can expect to see otherwise. Any machine operating in the real world will always need to be able to contend with events it can neither control nor predict, and that means always having built in safety margins.

[SP Cook]

Also, even in a world where all cars are automated, bikes and peds won't be. And neither will deer (or chickens). Or the presence of ice. Or...

The sort of unsignalized intersection depicted in the video where all vehicles coordinate seamlessly with extremely close tolerances would be achievable in laboratory settings but is not something we can expect to see otherwise. Any machine operating in the real world will always need to be able to contend with events it can neither control nor predict, and that means always having built in safety margins.

Excelent point. 

Think of how many factors have to be taken into account every second when driving.  1000s.  With 10s of 1000s of decisions made every minute. 

Just one sensor fails and BOOM.  Or if the computer running the whole thing reaches a level of advancement never achieved in computers ever, and "only" slips a number or crashes (pun intended) every 100 millionith time, then it is only a few months before every person on every road is in a crash.

They cannot even make a GPS that works.  It is all science fiction.

[Zeffy]

Most of my commute is on 2-lane roads (meaning one lane each direction). I tend to keep up with the rest of the pack, which is normally going 10-15 over the speed limit unless I'm wary of cops prowling or if they are going really fast. I think the people that go the posted speed limit on these roads when people ahead of them are not creates these jams as well as frustration for the drivers behind the guy going the speed limit.

But if breaking the law is safer than obeying it (slower = more aggravation leading to more aggressive behaviors) then why are we still posting low speed limits in areas that clearly can handle higher ones? I know of a 40 zone with a few houses on one side and farm fields on the other, but it's wide open and people can easily do (and routinely do anyways) 50 on it. My guess is to make a buck off the unlucky sap the cops decide to go after. 

[vdeane]

That, and there's a couple erroneous perceptions that cause people to support low speed limits:
-"If you raise it to 50, then everyone will just go 60!"
-"If people go faster, our roads will become death traps!  In fact, you should lower the speed limit to 30.  It's not safe if people go faster!"

[jbnv]

I think this one really sums up everything

No possessions means no cars, hence no traffic, hence no traffic jams.   

[kalvado]

That, and there's a couple erroneous perceptions that cause people to support low speed limits:
-"If you raise it to 50, then everyone will just go 60!"
-"If people go faster, our roads will become death traps!  In fact, you should lower the speed limit to 30.  It's not safe if people go faster!"

My impression is that everyone so used to true speed limit = posted +10-15MPH, that it is really hard to implement euro-style strict limiting - and that severely reduces options for situations when a hard limit is really required.

[20160805]

Most of my commute is on 2-lane roads (meaning one lane each direction). I tend to keep up with the rest of the pack, which is normally going 10-15 over the speed limit unless I'm wary of cops prowling or if they are going really fast. I think the people that go the posted speed limit on these roads when people ahead of them are not creates these jams as well as frustration for the drivers behind the guy going the speed limit.

But if breaking the law is safer than obeying it (slower = more aggravation leading to more aggressive behaviors) then why are we still posting low speed limits in areas that clearly can handle higher ones? I know of a 40 zone with a few houses on one side and farm fields on the other, but it's wide open and people can easily do (and routinely do anyways) 50 on it. My guess is to make a buck off the unlucky sap the cops decide to go after.

I agree with your point on speed limits.  We need to start setting speed limits at the 85th percentile, instead of criminalizing 85 percent of drivers, and we need to crack down on people who do exceed the speed limit.

Instead of freeway traffic flowing at 75 mph in a 65 mph zone, I think it should flow at 75 mph in a 75 mph zone.