Cancelling out traffic waves
 

Just about to dive into the usual commute home, when I found this interesting site. An engineer made an observation in his own commute home. He 'saw' the exact analogy of simple fluid dynamics with all the other cars around him. He experimented by being a 'lubricant' to the usual stop-&-go dynamics. Using best judgment & observation he kept his vehicle at a deliberately slower but 'steady' rate of speed to uniformly distribute the flow of his car lane. There maybe a large gap but he avoided the intermittent use of brakes, but he helped maintain a more efficient rate for his lane.

Might get some frustrated overtakers & tailgaters (LA traffic) but I'll give it a try tonite.

http://www.youtube.com/watch?v=iGFqf...layer_embedded

I do that but it's nearly impossible to impact anything other than a really small "local" flow territory, as around here, as soon as you're not tailgating, recreational lane-switchers push into that space.... causing you to be tailgating. Oh well, my vehicle's movement is "fluid" anyway. :rolleyes:

This is before the video. It has lots of interesting stuff on it. I said it before I really think there should PSA announcements on this stuff. Or at least cover it in Drivers ED. The lane jumpers and brake stomper and not let you in will always kill the flow.

i'm absolutely amazed on my daily driving route how many people drive behind me. i think they know the light patterns too, that's why they patiently glide with me.

I try to save the guy behind me gas, whether he knows it or not. This includes not cutting people off, but also coasting up to red lights and smoothing out traffic waves. It also means accelerating quickly away from a light that just turned green if another driver is growing rapidly larger in your rear view mirror. If there's a bottleneck in the road, try to get as many cars through as quickly as possible. I feel this means driving quickly and following closely, but within the range of what is safe, of course.

I deliberately change into a lane when the distance between cars there is on the rise, and I never merge into contracting flow. So if you're cancelling out a wave, I will jump in front of you while the wave is expanding.

Well the experiment took me out of my automatic 'lizard brain' as I drove home. I was more actively aware of the red rear lights at least 4 vehicles ahead. By studying these four 'rubberband' with each other, I adjusted accordingly. Aware of the LA driving style, my front gap was not wide enough at first but then I adjusted longer gaps that I no longer have to tap the brakes. Overtakers only appeared when we merge with more interchanges. Most interesting & fortunate, there was a Honda Accord driver behind me, conveniently stayed behind me with a comfortable distance, for about half our commute distance. We were at the #2 lane, yet we were comfortably moving along.
At the beginning it was slightly stressful, as I was accessing too much situational info but I settled down & the flow was much smoother.
My immediate observation is that I was really mimicking the maintained & lower speeds of long-haul trucks...plenty of spatial distances yet steady flow.
A new commuting style.

This doesn't always work, as there are jerks who keep aggresively accelerating and braking, instead of driving smoothly, even though they have no chance of passing.

Maybe ecodrivers should have flashing lights and a sign in the back saying:

What if there was a group of hypermilers doing "wave cancellation" in each lane such that they cannot be passed?

A secondary wave would result. It only takes on person slowing down to start a huge wave.

http://www.youtube.com/watch?v=Suugn-p5C1M

I saw that video a few weeks ago (the first one about waves) and started to leave gaps to cancel out the waves - I was adjusting the nut behind the wheel anyway.

I have two spots on my daily grind to do this. One spot is where traffice from one motorway merges onto the road I'm already on. I tap "merge" but what of course I mean is that everyone joining the road seemingly has to IMMEDIATELY DART INTO THE OUTSIDE LANE AS SOON AS POSSIBLE, whether or not there is anyone (e.g. me) there. :eek:

Although its frustrating to be stuck behind some muppet in a BMW 318, engine screaming as his "ultimate driving machine" fights the laws of physics to gather momentum, the satisfying payback for this comes about 1/2 a mile further up the road. At this point the road climbs quite steeply and the traffic all now congregated into the outside lane starts to back up in waves. And I just cruise past on the usually empty inside lane.

As well as not havign the frustration of stopping in a wave I also don't lose speed I have to make up later, so I save FE.

As for helping others save FE I've kind of given up. If I try to break the waves then I just end up with another muppet an inch or so from my tailgate. Pretty pointless as I now subscribe to the "sharp acceleration back to speed" principle so they end up being left behind a lot.

Dziekuje, Piwo! I got a good laugh out of that one.

Unfortunately, I don't think that would work in the Chicago rush hour traffic (or any hour, for that matter.) I've tried that style of driving myself, and I've noticed that the most cars subscribe to the "nature abhors a vacuum" (traffic jams abhor more than one car length?) concept. If there is an opening in any lane, it will immediately be filled with another car.

I noticed this when I started hypermiling. Usually, when I was a left laner, I was the one flipping back and forth trying to get another car ahead and going gas/brake, gas/brake.

I noticed another advantage to hypermiling and similar to this. There is one merge where there is a busy 3 lane onramp entering my 8 lane divided highway on the right. One by one the lanes merge and end. In my left lane days I ALWAYS was in the left lane and had to come to almost a complete stop when this traffic merged down into our 4 lanes. Then I would gas/brake, gas/brake along for maybe ¼ to ½ mile to get out of it. Traveling at 60 mph (psl 65 mph) in the right lane I noticed that I would not even have to slow down most days. In fact I might have to slow down, not stop, once every 2 or 3 weeks. What I see is that I used to be right in a pack and would have to brake because all the other vehicles were braking. For some reason, by me going a few mph slower, I am just about always between the packs of vehicles when I reach this merge. Also the merging vehicles all zip over to the left ASAP and cause those lanes to have more traffic entering and everyone leaving the left lanes.

I know I am not adjusting my speed to avoid the traffic, this is my regular commute and I have the speeds down. I come to the top of a hill before this spot doing 55 mph, and I can see the traffic merging ahead. I accelerate to 60 mph (slight downhill) just before the merge and by the time all the lanes have merged (slight uphill) I am going 55 mph and hit my exit at 50 mph FASing to the light with just enough speed so as not to piss folks behind me off.

Just thought it was interesting that by going a little slower than the major flow of traffic I have avoided using brakes for this merge.

OK! LET ME VENT! I HAVE BAD MEMORIES!
i was in the air force. we marched a lot.. it was boring, but efficient.
along roads where we had to be single file, we would walk.

my lastname initial is near the end of the alphabet, so i was one of the few on the end of the line. the waves produced at the front of the line were so exaggerated once they reached us at the end.
it was terribly hard and painful to walk a few steps then run to keep up.. walk.. run alot.. walk.. run alot, repeat.

i think everyone should experience hours of that. just so i don't resent it so bad.

...it's also called "rubber-banding" where traffic cyclically 'bunches up" and "stretches out" over and over again.

...one (ugh!) countermeasure to this are California's "on-ramp" traffic-lamps which keep the number of "on-rampers" trying to get onto the freeway at a single time (usually right after a cross-street red-light) from "crowding" the slow-speed (right) freeway lane.

...a single Highway Patrol car in the high-speed lane also works too.

Back in the Seventies during the gas crisis, when the 55 MPH speed limit was the national obsession and became law, some state highway patrols decided it would be a good idea for them to drive three patrol cars abreast of each other on interstate highways at 55 to keep traffic from passing them. They stopped that practice because it was found to be unsafe.

Hey, if anyone wants to drive more slowly than other traffic, that's their privilege - but not in the left lane. Live and let live.

Over the past year or so I've noticed a trend toward a higher percentage of the drivers behind me noticing what I'm up to and staying patiently behind me rolling up to the stop light. And a curious skeptic will then notice with how much remaining momentum we can cruise across the intersection when light turns green. So there's hope for mankind yet.

BTW here's a pretty cool JavaScript microsimulation of road traffic:
Welcome to the Physics and Traffic Homepage of Martin Treiber
You can adjust the various traffic volumes and observe the effects.