Supply House Times

Avoid Left Turns

May 12, 2009

No, I’m not making a political statement. In any case, it’s too late for that now that Nov. 4 has come and gone.

Instead, I’m suggesting that manufacturers and distributors can save significant money from fuels savings by instructing drivers to avoid all left turns, even though that means adding a few blocks to a journey by circling with right turns. The world’s largest delivery fleet operator, UPS, saves about 3 million gallons of gas a year doing this.

UPS found that idling while waiting for left-turn signals or clearance usually guzzles more gas than driving around a block. They save still more by instructing drivers to shut off the engine at all stops, no matter how brief. This is another UPS policy that they calculate can save $188 per year per driver - at $4/gallon gas. (It also begs the question of whether shutting off the engine while waiting in left-turn lanes could save even more fuel than driving around the block. I put this question to UPS but never received an answer.)

UPS also uses sophisticated software to help in route planning. The technology aims to shortcut the so-called “traveling salesman” problem that has bugged the world’s top mathematicians for a couple of centuries. Simply stated, it is virtually impossible to find the most efficient route between more than a handful of locations. When traveling among 10 cities there are more than 180,000 possible routes. Bump that up to 61 cities, and there are more possible paths than atoms in the universe. If you don’t believe me, check out this article.

Logistics software programs tackle this dilemma by seeking approximate shortcuts rather than perfect efficiency. For instance, a workable solution to the traveling salesman dilemma is to schedule deliveries to the closet remaining stop on a route - something that’s pretty much intuitive to most distributors, I suspect. While more efficient solutions to a delivery run are possible, you’d go nuts trying to find them. The closest next location tactic works reasonably well on average.

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