The Corridor Effect

[Tango Charlie]

From the '100+ Hypermiling Tips';

14) The 'corridor effect'
All else being equal, traveling at a constant speed on a freeway within a flow of traffic (in the same direction) is more efficient than going the same speed in isolation. The reason is aerodynamic: a flow of traffic generates a localized wind current in the direction of travel. You will benefit from this artificial breeze.

This morning I was sixth in line behind a large truck. The other five cars were spaced somewhat evenly about 10 to 15 yards apart, which I mentally noted as being out of the ordinary. Usually they instinctively bunch up on each other. (I also just realized that I was using my Marlin Perkins voice while making that mental note...)
I have enjoyed the benefits of drafting and the corridor effect before, but this morning's circumstances were quite pronounced. I was able to cruise along about 20 to 25 yards behind the procession and noted much less throttle needed, and corrospondingly the Insight's instantaneous MPG reading was significantly higher than usual along that stretch of my commute.
Has anyone else enjoyed the corridor effect?

[Fat Charlie]

Yep. But it's more fun with Steve Irwin's voice.

[gone-ot]

Originally Posted by Tango Charlie

From the '100+ Hypermiling Tips';

14) The 'corridor effect'
All else being equal, traveling at a constant speed on a freeway within a flow of traffic (in the same direction) is more efficient than going the same speed in isolation. The reason is aerodynamic: a flow of traffic generates a localized wind current in the direction of travel. You will benefit from this artificial breeze.

Has anyone else enjoyed the corridor effect?

...NASCAR drivers do every race day, following the car ahead by mere inches at 150+ mph speeds, even the last car in the "train."

[ecomodded]

I also notice the effect but its usually detrimental to my mileage because the flock of cars is always traveling faster then my preferred speed, under 60. I agree its unusual to see cars spaced neatly apart floating down the highway, more often then not there is a mini race circuit with AL Unser jr. fighting for position. I like to find a slow moving semi, rv or uhaul and use him as my wind break.
If i had to choose a voice over for my announcer it would have to be Howard Cosell announcing the speeding cars position in their run away pack, they seem to be so serious.

[botsapper]

On some long distance drives, I've 'attached' to some multi-vehicle (usually three cars) convoys. Admittedly not eco, we have been faster than the usual traffic but it was done with very smooth lanes changes. Rabbit, middle & tail-end Charlie changes every once in a awhile. It kept you more alert than usual and very aware of traffic dynamics far far ahead in the distance.
In eco-mode, (when you've already done a couple of hours of driving) I've attached to multi-truck convoys that have a very steady rate on the right lane. Unfortunately, very numbing experience.

[skyking]

Originally Posted by ecomodded

I also notice the effect but its usually detrimental to my mileage because the flock of cars is always traveling faster then my preferred speed, under 60. I agree its unusual to see cars spaced neatly apart floating down the highway, more often then not there is a mini race circuit with AL Unser jr. fighting for position. I like to find a slow moving semi, rv or uhaul and use him as my wind break.
If i had to choose a voice over for my announcer it would have to be Howard Cosell announcing the speeding cars position in their run away pack, they seem to be so serious.

That's why I dig the open highways and the trucks at 60. I keep back and over a bit to one side so they see me. I figure the negative aero effect is offset by not being an A-whole. karma points count in my book.

[aerohead]

In the 1920s and 30s,during 'coastdown' tests of Paul Jaray's- designed Zeppelin LZ-126 (USS Los Angeles),Wolfgang Klemperer and NACA (NASA) testers had to include this mass of air which traveled along with the airship in the drag calculation.
19th-century race hull designers observed it on ships.
Railroad train drag testing reported on such a thing with respect to the boundary layer.
Hucho has a section on 'convoy' driving which doesn't directly mention a 'corridor effect',although it would be embedded within the phenomenon.

[gone-ot]

aerohead -- excellent comment, I'd totally forgotten about the "trains-in-tunnels" and their (basically) 360-degree "corridor" effects.

[ksa8907]

ill actually drive faster if i have to in order to stay behind someone rather than push my own air. even while going faster i get better mileage. i.e. rather than going 60(speed limit), i might go 65 or 70 if it means staying behind someone.

btw, i do NOT drive too closely, plenty of braking distance. no less than 50ft, typically about 75-100ft if i had to guess.

[Tango Charlie]

Yeah, I agree, ksa8907. Just this morning again, I was third in line behind a tanker and was able to blast along at 60, getting what I usually get at 52 mph by myself. It helps not P.O.ing traffic behind; the whole karma thing like skyking mentioned.
But the corridor, in my mind, is different than drafting. Related, but different. You can trail quite a bit further back when you're in a corridor.

Interesting comment about the airships, aerohead. I'm thinking it was primarily due to skin friction drag? A lot of surface area on those monsters.

Oh, and Howard Cosell would make an excellent replacement for Marlin Perkins; Steve Irwin is just a little too excitable for me. Ha ha! I'm showing my age.