Right turns only save gas?

[DawnStorm]

I've been hearing this lately, the rationale being that you don't sit and wait till it's clear the way you do when you make a left turn. Doesn't sound worth it to me.
Chow if need be; I couldn't find it on the reference pages.

[A Turtle Named Mack]

Obviously that wouldn't make sense in many circumstances, but if you have a lot of stops and can plan your trip to make mostly right turns, you would save idling time. Somewhere here on Snopes there is a thread about UPS planning their drivers' trips to make mostly (not exclusively) right turns. A UPS driver confirmed it, as I recall. But that is mostly, not exclusively, and it takes a massive computer system to plot it all out.

Ah-hah found it - http://message.snopes.com/showthread.php?t=6596

[DawnStorm]

Thanks for that link; interesting responses. I hate making a left turn unless there is an arrow; I call arrowless traffic lights mercy lights in that you are at the light's mercy if you need to make a left turn.

[Meka]

I think it would depend on the size of the block you'd have to go around versus traffic conditions at the intersection you'd otherwise be turning left in. If it's a matter of taking a fairly long detour versus waiting for a single car to pass you in order to turn left, I think most people would wait and take the left.

I agree with Meka, although the size of the block I don't think would make a lot of difference. Here, many blocks are oblique, and some are wider than they are long, essentially one block long, two wide, unless you try to slip down an alley...which is probably blocked by parked vehicles.
Also would depend on traffic. Most times here there is only one, maybe two cars to wait before turning left, if any at all, and it would take much longer, and use more gas, to go around the block that wait for one car.

Finally, the amount of gas used idling is much less than gas used accelerating. IOW, if you're idling, you are using a little gas, but step on the gas turning right, then accelerate to speed again to go around the block, and assuming you're wanting to go in the same direction, you'll have to make at least one more turn, probably left, to parallel the road you were originally on.

[Judecat]

I'd also have to question how much gas you are going to save by making only right turns and going several blocks out of our way just to avoid waiting for several seconds to make that left, even if you are someplace with an actual straight street grid. The part of town I live in you'd never get where you were trying to go if you didn't make left hand turns. (I mean that very literally, the closest route from my MIL's house to ours has several intersections that prohibit left turns during rush hour, and we have to go at least a mile out of our way to get to the road on the other side of us where we can make that right turn into our nieghborhood.

[bcampbell]

I'm wondering if this theory in more about aggregate fuel usage rather than for the individual.

At really busy intersections, it's not uncommon for only a single car to make it through a left turn. I'm not sure about other state but in New York, traffic law says that when taking a left, you're supposed to enter the intersection if there are no vehicles in front of you and are allowed to complete your turn when the intersection is clear even if the light turns red. This lets at least one person through for each cycle.

If traffic is heavy, this means each car will sit at the light for n cycles where n is the number of vehicles in front of it. That can be a long wait, and a lot of idling at 0mpg. Consider that all of these vehicles are idling and it starts to make sense to allow people to make right turns only.

Also, it's much more fuel efficient to accelerate from a slow speed, even 5 or 10 mph, than from a stop. For this reason traffic circles (rotaries) save lots of fuel... as long as you're not going in a circle for four hours (look kids, Big Ben, Parliament!).

[BamaRainbow]

When I first saw this thread, I have to admit I had a slightly different take than some others have posted.
In a sense, you do save gas (albeit an incredibly trivial amount*) by making right turns as opposed to left turns when driving standard streets. The width of the lanes you have to cross in making the left turn create a very trivial (we're talking a couple of yards or meters at most) amount of "extra" distance for the car to travel. (Obviously, a left turn from a one-way street onto another one-way street would be no different than making a right turn on a pair of standard streets.)


*Since a left turn would add less than 50 feet, the turn doesn't even amount to 1/100th of a mile. A car getting 20 MPG will go 105,600 feet on one gallon of gas--in other words, over 2100 of these 50-foot left turns. Somehow, I can't see someone making enough of these left turns on a full TANK of gas to make any significant gas savings. (It's sort of like driving 30 miles to save 25 cents a gallon. If your gas tank is only 10 gallons and you get 20 MPG, you'll waste nearly a third of your gas just travelling to and from the station. If you'd be paying $2.50 a gallon--$25 for a tank to last you 200 miles--but drive to pay $2.25 a gallon--$22.50 for a tank that only lasts a net 140 miles--then, in the long run, you're actually paying more money for that 25 cents/gallon savings.)

[We'veBeenHad]

My grandfather wanted to see a world with no left-hand turns at all - only jughandles. It's kind of extreme, but more jughandles and cloverleafs wouldn't be a bad thing in terms of accidents, stoplights, and inconvenience, IMO.

[Meka]

Something else to consider. Around here, there are a lot of traffic lights - lights between fairly busy streets and smaller, residential streets - that are rather notorious for almost never going green for the side street. If the object of always turning right is to minimize the time spent idling at stoplights, then in this situation, you'll end up waiting longer for the light to change after going around the block than you would waiting for a break in all but the heaviest traffic in order to turn left. Even without added fuel consumption of taking a detour (easily half a mile or more around here) you'd burn less fuel turning left.

Now heres aother take on what is going on under the hood, anyone who has a engine heat indicator instead of a warning light knows that when you sit idling the engine temp increases. The hotter the engine gets the more fuel evaporation happens, which is the same reason that its recommended that when you start your engine you cut back on your warm up time. Also idling causes engine stress, a car is more energy efficiant on the high way mainly because the engine runs at a steady speed and runs cooler at higher speeds then in stop and go traffic. Another thing going on under the hood is carbon build up, an idling engine doesn't burn fuel as cleanly as an engine running at a higher rpm, remember when dad would say, I need to get out on the express way and blow some of the carbon out? An engine that idles builds up carbon deposits inside the combustion chamber, resaulting in sticky vavles and fouled spark plugs, same with cars that do a lot of slow speed trips.

Now the other reason right turns work at saving fuel is by planning your trip to the stores. Most people store hop, store A is on the left store B is on the right and store A is first in line so I'll stop at store A first even though I have to cross traffic when I go to store B. When they leave store B to get home they have to turn left across traffic a second time. If they had went to store B first then store A there would only be one left turn and they would only have to cross traffic once.

Where people get confused on the right turn tactic is the way their stores are. Store A could be on the north side of town and Store B is on the south side of town 10 miles away. Right hand turns only work when stores are lined up on one or 2 streets. If store A is 10 miles from store B then it won't work, the trick on that is finding out the roads that have the least stops.

But idling cause engines to heat up and fuel evaporates. Then theres also the problem of lower rpms causing carbon build up and gasoline engines carbon up badly while idling. Ever see a car that blows black smoke out of the exhust when the driver steps on the gas? That is carbon build up, it will also cause the car to run after the engine is shut off.