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UPS and the art of sorting nearly a million packages a day

At the global cargo company's Louisville air-distribution center, up to 900,000 packages are sorted each night. It's impressive to watch.

At Worldport, UPS' air-distribution facility in Louisville, there's 5.1 million square feet of space and 30,500 conveyor belts comprising more than 170 miles.
For more photos from Worldport, click on the image above." credit="Daniel Terdiman/CNET" />

LOUISVILLE, Ky.--I grew up in a household with two subscriptions to The New Yorker. How could we not? My father and my stepmother both needed their own copy of each issue.

With that as part of my background, how could I not become a lifelong fan of the magazine?

In 2005, New Yorker writer John McPhee published what instantly became one of my favorite pieces of all time, "Out in the Sort," a long treatise about the United Parcel Service's Worldport air-distribution facility here. Among his many detailed descriptions of this gargantuan operation, and the one that stuck with me ever since, was of being on an observation deck high above the countless conveyor belts on which packages of all kinds were whizzing by in every direction as some of the belts rose and others fell. He said it was like looking down into the Grand Canyon.

From the moment I read that, I said to myself that someday, I had to see that for myself.

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Well, very early Friday morning, as dozens of UPS cargo jets were streaming into Louisville International Airport, where Worldport is located, loaded to the rafters with boxes and letters and odd-shaped packages, I finally got my wish.

I was here as the latest visit on Road Trip 2008, my journey through the South in search of the best destinations the region has to offer. And as we walked close to the observation deck that I'm sure McPhee had been looking down from, my eyes began to get very wide.

We approached the edge and I looked down. Before me, it was just like I had read--a deep chasm out of which conveyor belts ferrying packages of every imaginable size and shape were climbing up out of the floor while others plunged down from above to the floor far below. Some were going north-south, others east-west, and some were changing directions as they went around corners (see video below).

There are several reasons Worldport is here in Louisville. But perhaps two most convinced UPS brass at the company's Atlanta headquarters to pick this city.

First, it is fairly centrally located and within striking range of all of UPS' hubs around the world. Second, the company was able to build its 5.1 million-square-foot facility directly between two parallel runways of the airport here, allowing it to land a plane about every minute during each night's peak arrival period, when packages from just about anywhere you can imagine arrive to be routed to their eventual destinations.

It turns out--who knew?--that UPS operates its own airline. In fact, with 264 heavy jets--including dozens of Boeing 757s, a number of Boeing 747s and many others--it is the world's ninth largest air carrier. It just doesn't cart many passengers around. At least not of the sentient kind.

And each night, about 90 of those jets arrive at Worldport, up to 70 of which can dock at any one time, during a mad rush of package distribution and re-distribution that lasts about five hours. If you're not able and ready to stay up until at least 3:30 a.m., then you're not fit for a Worldport visit worth your time.

Of course, simply being able to handle up to 900,000 next-day air packages each night--and another 300,000 to 400,000 second-day air parcels during the day--isn't easy. In fact, being able to do this is the special sauce that makes Worldport one of the biggest masterpieces of industrial wizardry that I've ever seen.

Imagine: During the course of moving off the 90 aircraft they've come in on and are immediately heading back out on, each of those 800,000 to 900,000 packages are touched by human hands just twice, once at each end. In between, Worldport's automation process performs its magic, keeping a stream of parcels moving steadily in a manner that is hypnotic to watch.

A UPS 757 unloads a cargo bin, otherwise known as an "air can." Daniel Terdiman/CNET

Here's how it works: Each package shipped by UPS is affixed with what is known as a "smart label." You've seen them. They're the white sticker with a bar code, a tracking number, your name and address, and other pieces of information.

When a package is taken off a plane, a UPS worker places it on the first conveyor belt with its smart label facing up and to the left. Over the next 15 minutes or so, it will travel belt to belt, making it from the dock where it arrived to the dock from where it will be put on the plane that will take it to the distribution center closest to its destination. Along the way, it will go through as many as five scanners, each of which reads the smart label and then uses the information it gleans to direct the package onto the right conveyor belt to get it closer to the right dock.

One fascinating element of the system is the minute timing that allows the packages to move seamlessly along their route, switching from belt to belt without ever needing to stop.

To watch it in motion is confusing. How, you ask yourself, can so many packages make their way through such a complex system without countless mistakes and without needing to slow the belts down to switch the boxes or envelopes from one belt to another.

A package runs through one of the five scanners it will encounter on its way from arrival to departure. Each scanner helps route the package closer to its final destination. Daniel Terdiman/CNET

The answer is timing. The system is designed so that, based on the scans, it knows the exact distance between each package and how long it takes each of them to move through the process. When a box gets to a point where it's necessary to shift it to another belt, the system knows, because of how long it's taken to get there from a previous transition point, and a little device pops out to shove it toward where it needs to go.

Here are some numbers about Worldport.

It can handle as many as 416,000 packages an hour. It has 30,500 conveyor belts that comprise 170 total miles of belts. There are 326 different positions for unloading packages and 1,480 for loading. And there are 8,372 tilt trays sorters, each of which delivers a package into the hands of the person who will ultimately place it into the bin that will then be put onto an airplane.

In truth, it's hard to really explain Worldport. This is, after all, a $1.1 billion facility that employs thousands of people and is currently being expanded to be able to handle nearly half a million packages an hour.

But what is clear, when you look deep into the guts of the Grand Canyon here, is that the planning and implementation of the systems involved are one of the most impressive pieces of engineering in modern industrial history.

I kept looking at the massive numbers of packages zipping by, at the miles of conveyor belts and the vast open space in the building and thinking that it was kind of funny that I'd come all this way to complete a wish I'd had for more than three years.

But watching Worldport in motion, hearing the jets landing and taking off, seeing constant motion everywhere you look and knowing that this is what is behind the delivery of the many UPS packages that get sent to me, I know that my delivery needs are in pretty good hands. And so are yours.