# Factoids of the Day

From the latest National Geographic cover story on malaria:

“Some scientists estimate that one out of every two people who have ever lived have died of malaria.”

From the Times:

“Last year, UPS cut 28 million miles from truck routes – saving roughly three million gallons of fuel – in good part by mapping routes that minimize left turns.”

July 12, 2007

How does minimizing left turns save miles? I understand that it saves time and fuel, but not how it saves miles.

2. #2 Pato Viejo
July 12, 2007

Good question, Fermi. I wondered too. It would seem that the difference in distance, if any, depends primarily on the actual route and configuration of streets along the way. But it also occurs to me that turning right saves the driver from having to cross two lanes. If the centerline of the vehicle characterizes its path, and there are two, 12-ft. lanes per street, then the distance saved is 24 ft. (each vehicle has to make a 90-deg. turn, so those cancel out). If they were saving 28 million miles through this method alone, that would mean they are avoiding a little over 6 billion left turns a year. Over a fleet of 88,000 trucks, if my math is right, each truck would have to avoid 70,000 left turns annually, or 191 per day. That seems like a lot. And anyway, turning right doesn’t necessarily help if your destination is to the left, so my guess is that their mileage savings has more to do with a clever solution tailored to the actual layout of the streets between point A and point B, albeit one that favors right turns.

3. #3 Elizabeth, MD, PhD
July 14, 2007

I agree with the time issue from another perspective. If I can get all my packages delivered in a given area within my shift schedule (because I avoid left turns), the fact that I do not have to return to that area tomorrow might account for those ‘saved miles.’