# Idling in traffic jams



## nerdly_dood (Mar 23, 2007)

I drove by a bad car accident this evening, which caused a pretty large traffic jam. It was clear when I got there that traffic was not moving, so I (and I alone) turned my engine off. There were probably about a thousand or so cars waiting to get by, not moving, and all I could see were still running, evidenced by a long line of brake lights in front of me and headlights behind me, all making the fog from cars' tailpipes glow like fire. I really wanted to yell out to everyone there that it's really not beneficial to anyone to keep idling like that, as if they couldn't see that traffic ahead was not moving and would not move anytime soon. (The highway was crossing a wide valley between a pair of low hills, so there was a very long line of sight.) Why do they keep their engine running? Traffic did move forward a few dozen yards every once in a while, but between those, I just kept the car parked.


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## ChrisZwolle (May 7, 2006)

Turning off the engine is useful when there is no movement at all, usually I shut it off after 3 minutes of remaining stationary. However, keep in mind heating and air conditioning do not work either that way. For example, a heated car will be very cold within 10 minutes if temperatures are at, or below freezing. An issue with the engine turned off in winter weather can also mean it won't start again, many people out there have old batteries.


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## Rebasepoiss (Jan 6, 2007)

^^ This makes me wonder: what about the cars that have start-stop systems? If you stay stationary for a while, in a traffic jam, for example, does the car automatically turn the engine on if the temperature within the car gets either too hot or too cold? I'm not sure whether you can turn the start-stop system off yourself but it would be rather annoying to sit in a cold(or hot) car in a traffic jam...


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## Suburbanist (Dec 25, 2009)

^^ Hybrid cars more or less work that way. The electrical battery will power cooling and heating systems. Moreover, modern middle-to-high-end cars have far better insulation.


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## Fargo Wolf (Oct 23, 2009)

The only time I've known people to shut their vehicles off is when waiting a roadworks and when there is a delay while the tow trucks right an overturned truck. Sometime they will shut their vehicles off at a level railway crossing too, especially with a two hundred car (wagon) freight train passing through the crossing.


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## Rebasepoiss (Jan 6, 2007)

Suburbanist said:


> ^^ Hybrid cars more or less work that way. The electrical battery will power cooling and heating systems. Moreover, modern middle-to-high-end cars have far better insulation.


I didn't mean hybrids, I meant regular cars that automatically turn off their engine if at a stand still(http://en.wikipedia.org/wiki/Start-stop_system). They have a regular battery which cannot support air conditioning, besides, these cars have no electric heating systems. So what if you stay at a stand still for a long time? Does the car automatically turn the engine on again to support heating/air conditioning after a certain period of time?


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## x-type (Aug 19, 2005)

we have signs for turning off the vehicles while standing in a row which is not moving. usually they are placed at sensitive places (such as tunnels), but i've seen them also at other places.
i turn off the engine almost always while waiting at railroad crossing.


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## nerdly_dood (Mar 23, 2007)

ChrisZwolle said:


> Turning off the engine is useful when there is no movement at all, usually I shut it off after 3 minutes of remaining stationary. However, keep in mind heating and air conditioning do not work either that way. For example, a heated car will be very cold within 10 minutes if temperatures are at, or below freezing. An issue with the engine turned off in winter weather can also mean it won't start again, many people out there have old batteries.


Maybe it was a big deal for other people, but I was just fine in the 40s F outside, with the latent warmth from the heater after it was turned off, even with the window rolled down so I could lean out like an idiot and stare at the helicopters.

There was about 10-15 minutes between creeping forward about 100 feet or so, with a total wait time (estimated) 30-45 minutes.


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## Penn's Woods (Apr 8, 2010)

nerdly_dood said:


> I drove by a bad car accident this evening, which caused a pretty large traffic jam. It was clear when I got there that traffic was not moving, so I (and I alone) turned my engine off. There were probably about a thousand or so cars waiting to get by, not moving, and all I could see were still running, evidenced by a long line of brake lights in front of me and headlights behind me, all making the fog from cars' tailpipes glow like fire. I really wanted to yell out to everyone there that it's really not beneficial to anyone to keep idling like that, as if they couldn't see that traffic ahead was not moving and would not move anytime soon. (The highway was crossing a wide valley between a pair of low hills, so there was a very long line of sight.) Why do they keep their engine running? Traffic did move forward a few dozen yards every once in a while, but between those, I just kept the car parked.


I would have done the same as you. I know in New Jersey there's an anti-idling law (which only applies in parking lots rather than traffic, so far as I know), and I believe the rule is you can't idle for more than five minutes. So, trying to be as environmentally conscious as possible but not actually having researched the point at which it becomes more wasteful to keep the car running than to turn it off and on, I'd take that five minutes as a rule of thumb (and if it's obvious after one minute you're not going to be moving in five, you may as well shut off now).


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## nerdly_dood (Mar 23, 2007)

Figured pictures would be useful.


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## Haljackey (Feb 14, 2008)

Apparently it is better for the environment to turn your engine off if you plan to idle for 30 seconds or more for the average car. 

Problem is if everyone did this at say a traffic light, someone who is slow at starting their car will delay traffic considerably. And then there are those who might fail to start their engines...

If I'm waiting to pick up a friend or something or wait at a railroad crossing I will turn the car off, but I won't if I sit at a light. In traffic, it really depends on how well (or bad) it's moving. At a snail's pace I'll creep along but if it's dead stopped you may as well turn it off until traffic begins to move.


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## nerdly_dood (Mar 23, 2007)

Haljackey said:


> Apparently it is better for the environment to turn your engine off if you plan to idle for 30 seconds or more for the average car.
> 
> Problem is if everyone did this at say a traffic light, someone who is slow at starting their car will delay traffic considerably. And then there are those who might fail to start their engines...
> 
> If I'm waiting to pick up a friend or something or wait at a railroad crossing I will turn the car off, but I won't if I sit at a light. In traffic, it really depends on how well (or bad) it's moving. At a snail's pace I'll creep along but if it's dead stopped you may as well turn it off until traffic begins to move.


This was dead stop for 10-15 minutes at a time. I had a feeling that would happen when I stopped there and I had plenty of visibility ahead so I'd know when to start back up for the next 100-foot creep ahead, so when I stopped I immediately turned it off.


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## diablo234 (Aug 18, 2008)

Isn't that pretty normal for Northern Virginia?

I have heard that it is the second most congested place in the US after LA (of course our traffic ain't no picnic either).


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## nerdly_dood (Mar 23, 2007)

diablo234 said:


> Isn't that pretty normal for Northern Virginia?
> 
> I have heard that it is the second most congested place in the US after LA (of course our traffic ain't no picnic either).


Not this section of it, that's definitely not the Beltway. That's US Rt. 29 east of Warrenton, a rural 4-lane highway, at about 9:30 PM.


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## g.spinoza (Jul 21, 2010)

I only turn my engine off at railroad crossings because _I know_ I will have to wait. In traffic jams you cannot be sure, so usually I leave the engine on.


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## nerdly_dood (Mar 23, 2007)

g.spinoza said:


> I only turn my engine off at railroad crossings because _I know_ I will have to wait. In traffic jams you cannot be sure, so usually I leave the engine on.


There was a very long line of sight ahead warning me when I'd have to start up again as I saw brake lights turn off. It helps that the car is an automatic.


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## urbanlover (Feb 14, 2005)

You could do this instead:
http://www.wpxi.com/video/26039432/index.html


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## g.spinoza (Jul 21, 2010)

nerdly_dood said:


> There was a very long line of sight ahead warning me when I'd have to start up again as I saw brake lights turn off. It helps that the car is an automatic.


One has also to see if the process of re-starting the engine produces less or more pollution than leaving the engine on at minimum regime.


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