What exactly is supposed to have happened here?

we have phantom traffic jams without solitons or jamitons – just go to “Périphérique” in Paris, or, closer to my heart, try to get to Warsaw airport from south on Monday morning :-)

In more serious mood: years ago I was shocked by the solitons and the implications of them – solitary or self-organizing wave patterns. But this math of jamitons is quite intriguing.

Cory – do you have any URL with papers or, maybe just more mathematical details?

What’s amazing is that this is not a new phenomenon, and we still don’t have it whipped…

Why is it, exactly, that we need to know the cause of us having to slow down? Is that somehow supposed to affect the fact that we have to slow down? It’s pointless to get frustrated about traffic patterns. Knowing why we’re in a traffic jam doesn’t alter the fact that we are in a jam. Is being pissy about it going to make it better?

It’s a point of pride for me that I do _not_ slow down to look at such things unless there are exposed flames over three feet high, or body parts in my lane.

There are ways to ‘bust’ phantom traffic jams, and in response to ANON#4, those people living 15 car lengths ahead of them are the ones that are going to clear the jam. One person won’t clear the jam, but they speed up its reduction.

Much in the way Phrunk mentioned with everyone having two car lengths ahead and closing to 1 as they accelerated being a solution, having one person with lots of space does two things, lets the cars in the jam move forward, letting the wave move forward with no new cars to keep it standing still, and lets/forces more aggressive drivers move in front of them , reducing the people that will feed behind them.

It works even better in a rolling blockade situation, sometimes done by coordinated truckers or by cops. If the jam is slowing everyone down to 20mph, if you approach it from a few miles away, block all lanes with cops/truckers, slow to 50 or 40 or whatever it takes, by the time the front line blockers reach the jam it should have cleared entirely, they can then slowly speed up to normal speeds. The slow down at 40mph will dissipate much faster than the 20mph jam.

Of course that requires only moderate traffic levels and some planning. It is cheaper than building wider roads though!

It seems to be human nature to desire knowledge, even if we can’t react on it. Why do you think 24hr news stations are so popular?

Problem is, it’s not.

In the Real World, whenever you add capacity, the result is that more workers buy houses further from the urban core, since the prices are cheaper and the commute is now “reasonable”; until the new capacity is exhausted and the roads are perpetually jammed, which then limits the rate of outward expansion once again.

Lather, rinse, repeat.

Having been stuck in traffic in the Berkeley Corridor almost daily, this theory does NOT take into account stupid drivers who leave about 8-15 car lengths between it and the next car.

Well they’re probably doing it because maintaining a constant speed is one way to unjam a phantom traffic jam.

Plus it allows people to change lanes and when they need to turn off the road instead of hitting their breaks and waiting for an opening in extreme situations.

In heavy traffic situations, I almost always leave as many car lengths in front of me as is necessary to maintain a constant speed.

The frustration comes form not knowing whether the jam-up is minor, and will clear in a few minutes; or is caused by a jackknifed truck ten miles ahead blocking three lanes, which will make you two hours late to wherever you’re going.

Variable speed limits BEFORE the jam might be able to lessen the jam. If you have to slow down a few miles before coming to a complete stop, it should allow the jam to break up a bit (or at least move “forward”) before you get there.

That, or build double-decker highways, where the upper deck is only avaialble as a detour when jams get to a certain size, so you’re no longer feeding the problem.

1. If there’s room for 8-15 car lengths between two cars, it’s not a traffic jam.

2. If both cars are travelling at the same speed, it’s not a problem.

or to cause one,

but if you’re so much smarter than everyone else around them that just couldn’t be true.

So, is it the intelligent man’s responsibility to fix the mess by out thinking everyone around him, or should he try not to piss everyone else off by acting in a way that causes as many problems as it solves?

I say it’s your call, but check your self-estimation of your own intelligence at the curb.

and by you, i mean that jack*** I was stuck behind on I-93 yesterday, not you personally.

If drivers merge early, then a few “cheaters” are able to use the empty lane to zoom past everyone. But then the drivers downstream won’t let the cheaters merge back in. Yet still the cheaters can force their way in slooooowly, which brings the full lane to a near halt. A huge backup develops in the full lane, making the empty lane longer, which greatly encourages cheating.

On the other hand, if everyone merges late, and takes turns at the merge point, and both lanes flow at about the same speed …then “cheaters” don’t exist. There’s no empty lane for cheaters to use. There’s no reason for the drivers in the through-lane to block the merging cars. In fact, cars in both lanes can then open up enough space to merge easily. Things flow like meshing gears.

JAM BUSTING
http://trafficwaves.org/

VIDEO: jam in the left-hand exit lane
http://tinyurl.com/m5m9cx

This kept the convoy moving, ensured there weren’t hold-ups, and meant that they got to the destination in the fastest possible time.

He felt mighty vindicated when they started trialling variable speed limits on certain motorways, to cut down on traffic jams in exactly this way.

When you have a planned lane blockage (due to construction, for example), is it better for drivers to use both lanes for as long as possible, merging a few feet before the actual merge point? Or is it better to make a single line as soon as you know a blockage is ahead?

In certain parts of the US, you would be despised for choosing the first option, but it seems to me it’s the much more reasonable option.

I do this regularly. If the driver ahead of me is going fast and then slowing down cyclically, I’ll give that car some more room. Basically I visualize a big rubber band between us, and I don’t accelerate as quickly as they do. The whole lane behind me eventually is running much better, much more smoothly. I am happier, and hopefully the people behind me are happier.

Though if I get too much distance in front of me then cars behind me are not so happy. I am perceived as slowing down the freeway too much. So I make sure not to leave too much space in front of me.

But professional truckers, driving through jams with a big empty space ahead, aren’t going slow.

Their speed is the same as the car ahead of them. Regardless of the size of that space, their speed is the same as the average speed of their lane. If they were going slow, then the empty space wouldn’t be unchanging, instead it would be growing.

Truckers use this “empty space” technique to free up clogged merge zones and bust traffic jams. Recently few non-truck drivers have discovered the trick and started using it. I see these big “jam busting” spaces more and more often in traffic.

In 2004, traffic scientist L.C. Davis won awards for discovering that, if 10% – 20% of people drove with no tailgating and computer-controlled fast reaction time, then traffic jamming becomes impossible.

Yes, those two cars enjoyed coasting along and they enjoyed constant but slow speeds but for every other car behind them (the ones beyond the sonic point) it was a truly frustrating exercise. And the buildup behind the two cars just grew and grew.

I agree that yes, BEFORE a traffic jam happens, having tons of space between cars are better to absorb the waves. However, if a jam has already started, how can leaving more than a car-length between you and the next be anything but detrimental?

I have also been in an underpowered car that could not accelerate 0-60 60-0 in 3 seconds. If all cars could and drivers safely drive them then the method would not be effective. But with trucks and slowly acceleration vehicles the net acceleration gets so slow that the jam will only dissipate late at night or something like that.