UPS trucks rarely make left-hand turns.
By favoring right-hand turns — unless making a left is absolutely necessary — UPS carriers save millions of gallons of fuel each year, and avoid emissions equivalent to over 20,000 passenger cars, CNN reported.
The practice began in the 1970s when UPS implemented a "loop dispatch," scheduling deliveries in a right-turning loop and starting with one side of the street first.
"Left-turning traffic typically has to turn against a flow of oncoming vehicles," Tom Vanderbilt, author of the book Traffic: Why We Drive The Way We Do, told CNN.
"This can not only be dangerous, but makes traffic build up, unless you install a dedicated left-turn 'phase,' which is fine but basically adds 30 or 45 seconds to everyone else's single time," he said.
A study on crash factors in intersection-related accidents from the US National Highway Traffic Safety Association shows that turning left is the cause in 22.2 percent of crashes, as opposed to 1.2 percent for right turns. About 61 percent of crashes that occur while turning or crossing an intersection involve left turns, as opposed to just 3.1 percent involving right turns.
Left turns are also three times more likely to kill pedestrians than right ones, the New York Times reported, according to data collected by New York City's transportation planners.
"A left-hand turn is also less fuel efficient," Jack Levis, UPS Senior Director of Process Management told CNN, "because your car's idling longer, which is also not good for your vehicle."
UPS does not ban left turns outright, says Levis: "We will make left-hand turns, but not ones that are unnecessary. We don't need to go in circles all day long by making only right-hand turns. We have tools analyze the number of left-hand turns for each route, and we can work out which ones are avoidable."