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-   -   Traffic experiments: a cure for waves and jams (improves other people's MPG too) (

MetroMPG 12-14-2007 04:45 PM

Traffic experiments: a cure for waves and jams (improves other people's MPG too)
This isn't specifically about fuel economy, but it applies.

This guy has written about "standing waves" in traffic, and how a driver either contributes to them, or (as he suggests) can help reduce them.

First off: here's a standing traffic wave, nicely illustrated (You should see an animated gif). We see this all the time:

Now his interest is generally about smoothing things out, but removing this wave (if you could) would also have the effect of collectively saving a lot of fuel by reducing herd mentality braking/accelerating around the wave.


The solution seems obvious: drivers with a smooth "calm" style will tend to damp out the waves and produce a uniform flow... and the few drivers who intentionally drive at a single constant speed will wipe out the waves entirely.
He suggests, when you spot a standing wave ahead of you (well ahead), opening up a large gap in front by reducing your speed. When the leading edge of your gap reaches the last car in the standing wave, the wave begins to shrink (cars are still accelerating away from the front of the wave). Ideally, your car reaches the wave area just as the last car accelerates away, and you didn't have to brake to a stop (neither did anyone behind you).

Lots more:

newtonsfirstlaw 12-14-2007 06:35 PM

I do this already, as part of hypermiling techniques.

The first initial acceleration I do is usually quick, then I coast. I try and time it so that I should still have some forward velocity by the time the next car starts accelerating, or if the next car will be stopped, by reaching zero velocity by the time I reach that car.

Sometimes I feel like making a flashing red LED sign saying "Red Light/Stopped Traffic Ahead!" to put on the back of my car for the people who insist on honking or extreme tailgating.

MetroMPG 12-14-2007 06:40 PM

I know what you're saying.

The angriest driver I've ever seen was a guy behind me in a truck while I was coasting up to a red light. He was literally screaming at me and gesticulating through his windshield - yet there was nowhere else he could have gone, except to this red light.

Fortunately that's only happened once to me - oh, and it was in Toronto (I generally don't see road rage around here).

SVOboy 12-14-2007 06:43 PM

Crazy torontulas!

Like newton, I do this already, as part of my ecodriving routine. Really helpful in ~30mph traffic on the highway.

trebuchet03 12-14-2007 08:16 PM

Great site.... I actually had a somewhat lengthy discussion with my roommate last week about simulating traffic... Traffic is a chaotic system (small input changes yield large output changes) - and is rather difficult to model solely because it's chaotic..... It will likely never happen - it was just fun to brainstorm :) If anyone wants to -do let me know :D

MetroMPG 12-14-2007 08:19 PM

Have you seen the site that has the adjustable traffic flow simulation? I'm thinking it's a Java app. Oval track. (If you have, you'll know what I'm talking about.)

Lazarus 12-15-2007 12:30 AM

I love that site. They should do PSA on this traffic stuff. Here's some more applett that are good.

MetroMPG 12-15-2007 10:51 AM

That's the one! Thanks for posting the link.

Undie 12-20-2007 07:43 PM

I often do this flattening out the wave when I'm on my way home from work. Its difficult in the heavier traffic near the plant. So many people especially in automatic cars see the guy in front move forward slightly and then they let off the brakes too and nudge forward usually 5 feet and then put on their brakes again. These annoying mini waves drive me nuts because I refuse to put my car in gear to move forward a couple feet. Sometimes then when the person in front of me actually starts moving and I start to move, if I don't gun it someone from the next lane jumps in. Sometimes its just not worth the bother. What do you guys generally do in heavier traffic?

MetroMPG 12-21-2007 10:52 AM

Luckily, I don't drive in heavy traffic all that often. But driving a manual shift in genuine stop, wait & crawl situations, where even the "accordion method" can't work, I also won't move the car every time the guy in front of me moves a few feet. But I won't gun it to prevent someone from sneaking in front of me either, despite the reptilian part of my brain screaming at me to stand on the go pedal.

Is this a daily experience for you? If it were for me, I'd be wondering about shifting the departure time a little bit. Sometimes just a short delay can make a big difference if you can avoid the volume peak.

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