The Science Behind Why UPS Trucks Avoid Making Left Turns

UPS avoids left-hand turns because SCIENCE, also increased risk of accidents and delays.

(MICHAEL GIL)

The United Parcel Service, UPS, is a massive operation, delivering an average of 18.3 million packages every day. They also have a tremendous amount of computing power at their disposal, with seven mainframes chugging away at data centers in Mahwah, NY and Atlanta, GA. That's on top of their 231,588 laptops and workstations, and 130,452 DIADs, those handheld devices drivers carry.

Very little of UPS's methodology escapes analysis by all this computing power. And one thing those computers have taught UPS is: Don't turn left across traffic unless you really have to.

Mathematician George Dantzig introduced the vehicle routing problem in 1959. It's a way of using data analysis to find the optimal way to get from one point to another. Many businesses, er, traffic in it. It helps make them more efficient, whether they're delivering packages like UPS or rounding up chickens on a farm. Obviously, it's one kind of problem with a few vehicles (or chickens), and another one altogether for a company like UPS, with 104,926 cars, vans, tractors, and motorcycles making multiple stops.

En route (DAVID GUO)

According to IFLS, UPS began with the assumption that the most direct route was the best route. But when they factored-in accident risks, travel time, and fuel use, it became clear that left-hand turns across traffic were a problem: They come with a higher risk of accident, and waiting for a break in oncoming traffic wastes time and idling fuel.

By keeping left-hand turns to a minimum, UPS says it's saved 10 million gallons of fuel, avoided the emission of 20,000 tons of CO2, and delivered 350,000 more packages a year. UPS senior vice president Bob Stoffel told Fortune, “We'll never have a person turn left to deliver on that side. We'll have someone go down the right-hand side and someone coming back down the right-hand side to avoid those left-hand turns. And that's where you get stuck in traffic trying to come back across."

(GRENDELKHAN)

The company will still authorize a left about 10% of the time if it's the most efficient way to go., maybe in a residential area with light traffic or if a right turn takes the driver too far out of the way.

UPS isn't the only proponent of avoiding left-hand turns. According to the National Highway Traffic Safety Administration, 53.1 % of traffic-crossing accidents occur with left-hand turns, compared to only 5.7% involving right turns. New York city transportation scientists have found that vehicle vs. pedestrian deaths are three times as likely with a left-hand turn.

Tom Vanderbilt, author of Traffic, wrote a piece in Slate in which he explained why traffic engineers hate lefts:

Left turns are the bane of traffic engineers. Their idea of utopia runs clockwise. The left-turning vehicle presents not only the aforementioned safety hazard, but a coagulation in the smooth flow of traffic. It's either a car stopped in an active traffic lane, waiting to turn; or, even worse, it's cars in a dedicated left-turn lane that, when traffic is heavy enough, requires its own "dedicated signal phase," lengthening the delay for through traffic as well as cross traffic. And when traffic volumes really increase, as in the junction of two suburban arterials, multiple left-turn lanes are required, costing even more in space and money.

So does this mean you should avoid making left-hand turns when you can? It may not matter in a residential area or out in the country, but if you're in a congested area, the answer is clearly yes. Unless you have a death wish and lots of time.

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  • Before the hurricane season even started in 2020, Arthur and Bertha had already blown through, and Cristobal may be brewing right now.
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Welcome to Hurricane Season 2020. 2020, of course, scoffs at this calendric event much as it has everything else that's normal — meteorologists have already used up the year's A and B storm names before we even got here. And while early storms don't necessarily mean a bruising season ahead, forecasters expect an active season this year. Maybe storms will blow away the murder hornets and 13-year locusts we had planned.

NOAA expects a busy season

According to NOAA's Climate Prediction Center, an agency of the National Weather Service, there's a 60 percent chance that we're embarking upon a season with more storms than normal. There does, however, remain a 30 percent it'll be normal. Better than usual? Unlikely: Just a 10 percent chance.

Where a normal hurricane season has an average of 12 named storms, 6 of which become hurricanes and 3 of which are major hurricanes, the Climate Prediction Center reckons we're on track for 13 to 29 storms, 6 to 10 of which will become hurricanes, and 3 to 6 of these will be category 3, 4, or 5, packing winds of 111 mph or higher.

What has forecasters concerned are two factors in particular.

This year's El Niño ("Little Boy") looks to be more of a La Niña ("Little Girl"). The two conditions are part of what's called the El Niño-Southern Oscillation (ENSO) cycle, which describes temperature fluctuations between the ocean and atmosphere in the east-central Equatorial Pacific. With an El Niño, waters in the Pacific are unusually warm, whereas a La Niña means unusually cool waters. NOAA says that an El Niño can suppress hurricane formation in the Atlantic, and this year that mitigating effect is unlikely to be present.

Second, current conditions in the Atlantic and Caribbean suggest a fertile hurricane environment:

  • The ocean there is warmer than usual.
  • There's reduced vertical wind shear.
  • Atlantic tropical trade winds are weak.
  • There have been strong West African monsoons this year.

Here's NOAA's video laying out their forecast:

But wait.

ArsTechnica spoke to hurricane scientist Phil Klotzbach, who agrees generally with NOAA, saying, "All in all, signs are certainly pointing towards an active season." Still, he notes a couple of signals that contradict that worrying outlook.

First off, Klotzbach notes that the surest sign of a rough hurricane season is when its earliest storms form in the deep tropics south of 25°N and east of the Lesser Antilles. "When you get storm formations here prior to June 1, it's typically a harbinger of an extremely active season." Fortunately, this year's hurricanes Arthur and Bertha, as well as the maybe-imminent Cristobal, formed outside this region. So there's that.

Second, Klotzbach notes that the correlation between early storm activity and a season's number of storms and intensities, is actually slightly negative. So while statistical connections aren't strongly predictive, there's at least some reason to think these early storms may augur an easy season ahead.

Image source: NOAA

Batten down the hatches early

If 2020's taught us anything, it's how to juggle multiple crises at once, and layering an active hurricane season on top of SARS-CoV-2 — not to mention everything else — poses a special challenge. Warns Treasury Secretary Wilbur Ross, "As Americans focus their attention on a safe and healthy reopening of our country, it remains critically important that we also remember to make the necessary preparations for the upcoming hurricane season." If, as many medical experts expect, we're forced back into quarantine by additional coronavirus waves, the oceanic waves slamming against our shores will best be met by storm preparations put in place in a less last-minute fashion than usual.

Ross adds, "Just as in years past, NOAA experts will stay ahead of developing hurricanes and tropical storms and provide the forecasts and warnings we depend on to stay safe."

Let's hope this, at least, can be counted on in this crazy year.

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