The real reason UPS drivers rarely ever turn left

If you've ever encountered a UPS driver on the road, chances are they would not turn left.

The idea might seem counterintuitive, but that's because UPS drivers don't always take the shortest distance in a given route.

Instead, their drivers are given specific predetermined routes which account for all manner of factors, and part of the calculation involves avoiding left turns as much as possible.

The theory comes from the vehicle routing problem.

This is where you have a set of different points and are tasked with finding the best route between them - with that usually meaning finding the shortest.

However, UPS now takes account of other factors in determining what the 'best' route is.

This could be things like fuel consumption, risk of traffic collisions, or roads with a lot of traffic.

That all sounds very plausible, but why would they choose left turn specifically, over the right?

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It's because in the USA traffic drives on the right.

That means that if you want to turn left you have to do so across the oncoming traffic.

According to UPS' criteria, this has a number of negative effects on the journey.

For example, while a driver waits for a gap in the traffic the vehicle is idling, which wastes both time and fuel.

Turning across the traffic also increases the risk of a collision.

In a country like the UK where you drive on the left, you would just reverse this.

UPS routes are designed to have as few left turns as possible, and only around 10 percent of the turns on any given route are to the left.

UPS has claimed that this policy has resulted in it using 10 million fewer gallons of fuel, emitting 20,000 fewer tons of carbon dioxide, and delivering 350,000 more packages per year.

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Not only that, but UPS even claimed that the efficiency from the routes meant it could cut the number of trucks in its fleet by 1,100, according to The Conversation back in 2017.

This reduced both the carbon emissions, and the total distance travelled by some 28.5 million miles.

That's quite an impressive claim just from designing a route very carefully.

But does it hold up?

Well, debunkers Mythbusters decided to put the theory to the test, albeit on a smaller scale.

They were able to confirm that despite making a lot more turns overall they did actually save fuel.

While in their one truck experiment they did end up travelling further, if you scale up the practice then it does actually lead to a shorter distance overall.

This idea doesn't work with every kind of journey, but it seems that a simple to follow rule has had huge benefits for UPS.