Traffic waves

[Undertoad]

http://www.amasci.com/amateur/traffic/traffic1.html

Might as well start its own thread rather than hijacking again.

Since I read the above piece, I drive the Schuylkill Expressway differently. I use the principles the guy talks about.

And I feel great about it, and I'm absolutely certain that I'm making a difference.

[glatt]

I don't drive in traffic jams very often, because I'm a public transportation kind of guy, but when I do, I try to do the same thing. It works out well.

[ladysycamore]

(from the article)

Rolling barriers made of State Troopers

OK, so here's how to dissolve a major interstate traffic jam. Start many miles upstream from the jam. Put a row of State Trooper vehicles across the road and have them drive towards the jam. They drive perhaps at 55 rather than 70 as everyone else had been driving. Nobody can get by them, and so all the traffic behind the State Troopers is moving at 55 or so. In front of them a vast space opens up. After many minutes, the traffic which had been feeding into the city traffic jams simply stops arriving. There is no new traffic for many minutes. The huge jam trickles away. Just as the last of it is gone, the row of State troopers and the 55-mph traffic arrives, and the jam has been transformed into miles and miles of slightly slow traffic upstream from the old location of the jam.

This actually happened years ago in MD. I was driving along I-695 towards the city, and suddenly the traffic slowed down, and everyone seemed to be rolling along at the same speed. This continued all the way to the I-95 exit split to go to Baltimore City (north) and Washington, D.C. (south). As I was bearing off to the BC 95N exit, I looked to my left at the traffic that was continuing on I-695 S. I saw that there had been a state trooper in each lane going exactly 55MPH (when it was 55mph..it's now 65mph). Later on that day, I heard about the new "rolling roadblocks" that the MD state troopers were trying out. Funny thing...I only remember it that one time and not hearing about it after that...strange...

I thought it was kinda sneaky, but clever.

[smoothmoniker]

I wish we had a viable mass transit here in LA. I take the metro trains whenever I can, but the system is not very useable yet. It doesn't go many places, is expensive, and the trains are almost an hour apart.

-sm

[Happy Monkey]

Aren't every two points in LA about an hour away from each other by car anyway?

[lumberjim]

i didnt have to read the link to know what it said. ask jinx. i've been commenting on this effect for years. one asshole can spill his coffee, and there will be waves for hours. i try to keep a steady speed to "erase" the waves when i can. i love the gif on the top of the page, it looks just like i imagined it in my little pea sized mind.

it's about cumulative reaction time lag. i try to look at the car in front of the one i'm following for my cues. keeping a peripheral focus on the one right in front for any unexpected idiocy, of course ( is that an oxymoron when the topic is traffic?...."unexpected idiocy", that is)

[lumberjim]

Originally posted by ladysycamore
(from the article)

Rolling barriers made of State Troopers

OK, so here's how to dissolve a major interstate traffic jam. Start many miles upstream from the jam. Put a row of State Trooper vehicles across the road and have them drive towards the jam. They drive perhaps at 55 rather than 70 as everyone else had been driving. Nobody can get by them, and so all the traffic behind the State Troopers is moving at 55 or so. In front of them a vast space opens up. After many minutes, the traffic which had been feeding into the city traffic jams simply stops arriving. There is no new traffic for many minutes. The huge jam trickles away. Just as the last of it is gone, the row of State troopers and the 55-mph traffic arrives, and the jam has been transformed into miles and miles of slightly slow traffic upstream from the old location of the jam.

This actually happened years ago in MD. I was driving along I-695 towards the city, and suddenly the traffic slowed down, and everyone seemed to be rolling along at the same speed. This continued all the way to the I-95 exit split to go to Baltimore City (north) and Washington, D.C. (south). As I was bearing off to the BC 95N exit, I looked to my left at the traffic that was continuing on I-695 S. I saw that there had been a state trooper in each lane going exactly 55MPH (when it was 55mph..it's now 65mph). Later on that day, I heard about the new "rolling roadblocks" that the MD state troopers were trying out. Funny thing...I only remember it that one time and not hearing about it after that...strange...

I thought it was kinda sneaky, but clever.

that's what I call "protecting and serving" way to go, cops.

[elSicomoro]

IIRC, tw brought this up some time ago...and russotto refuted it. Where are those 2?

[wolf]

I think they tried the rolling roadblock concept on the PA Turnpike between Ft Washington and King of Prussia during one of the construction phases.

[russotto]

The 55mph Maryland rolling roadblocks were for speed enforcement. Didn't last too long, probably when Maryland realized they weren't getting any revenue from it. Anyway, they caused massive traffic tie-ups behind them.

Anyway, you can try to eat traffic waves on the Schuylkill expressway, but it probably won't work. #1, Schuylkill drivers will pull in front of you as soon as you leave a gap. #2, the waves on the Schuylkill are generally caused by physical features (curves and interchanges). As for his other techniques -- use them, and you're contributing to a jam behind you even as you may alleviate the jam in front of you.

[Carbonated_Brains]

Wave def'n: A disturbance traveling through a medium by which energy is transferred from one particle of the medium to another without causing any permanent displacement of the medium itself.

Just to be anal it's not a wave, because the cars (the medium) are moving permanently down the line. For it to be a wave, and it would be a longitudinal wave because you're describing compressions and rarefactions, the cars would have to drive forward, shift into reverse, and repeat!

To redeem myself from this brash attempt at being technical, check out this traffic simulator

Bam!

[Katkeeper]

My concern in driving 270 and 495 around D.C. is that people will swerve in front of you whenever you leava a space. I have enough of this as it is because (defensive driving) I always leave a bit more space between me and the car in front so that I have time to react to anything the driver in front might do, and people cut in front of me.

I like to observe how little difference it makes if you lane change.
While it may seem that the lane next to you is going along faster, it soon slows and you pass the cars that had passed you. Though I have seen some really agressive lane changers who seem to work their way ahead by shifting to another lane, then shifting back again. Accident waiting to happen.

The Front Range of Colorado is as bad as any place. My second favorate "worst" commute is the stretch on I-25 between Colorado Springs and Denver. Forget about safe following distances - the other drivers won't allow you to create one. The moment you create a safe distance between you and the car in front of you, someone else switches lanes and fills it. So there we all are, a speeding wall of metal objects filling both lanes of the I going 80mph bumper to bumper and this wall is 60 miles thick (distance between the two towns). I make that drive with every one of my senses on red alert, constantly eying the cars behind me and to my left or right as well as trying to keep an eye on the traffic up ahead for those tell tale red break lights, meaning that in just 3 seconds we are all going to be collectively standing on our brakes, and I hope all the members of the team of the moment are up to their game today.

In number one spot for driving thrills is the stretch of I-70 from near Vail to Denver. Its an extremely mountainous part of I-70 with plenty of sharp curves and fairly steep grades and Vail is about where the congestion starts. Once again its bumper to bumper, 80mph all the way in to Denver. The fun starts if its after dark and raining. You'd think folks would slow down under these conditions but NO- oh! Try and slow down yourself and you're likely to be rear- ended by drivers coming up from behind. So there we all are, like a pack of crazed Mario Andretti's taking those slick, wet mountain curves at 80 mph with extremely limited visibility all the way into Denver. I guess its Colorado's answer to population control since there have been quite a few traffic fatalities due to this mass driving technique.

[BrianR]

The Pacific Coast Highway. California. Four lanes of bumper to bumper moving at 70mph (55 zone). Sheer dropoffs to the left and high, steep mountains to the right. Wife is reading aloud a news story about trucks with bad brakes. I point out the stream of logging trucks (ever seen a loaded one?) coming down the mountain roads to the right at 65mph or so with NO MERGE AREA!

Wife about pisses herself and forces me to take an alternate route home. I myself was not pleased about the mentality of those drivers although in fairness, they were more or less courteous and seemed to know what they were doing. It was more like being a cow in a stampede....everyone going in the same direction at the same speed and no fair trying to change anything suddenly. Turns and lane changes had to be set up miles in advance.

Brian

Yeah, I've seen 'em. We've got them here in Colorado (logging trucks), and they REALLY have them in Idaho where I lived for a year once. I think it must be a mandatory requirement to get a job driving one of those things that you be hopped up on methampetamines at all times. Those guys are CRAZY!