Nov 30, 2023

Print Every week 2 million packages enter and exit Amazon’s sorting facility in Otay Mesa. Within hours, they’re scanned, sorted by ZIP code, routed for delivery and loaded onto pallets where they’ll be delivered by USPS or Amazon vehicles. That’s an average. On busy weeks like this one and the rest of the peak holiday shopping season, the number of packages jumps to around 3 or 4 million. This story is for subscribers We offer subscribers exclusive access to our best journalism. Thank you for your support. There’s a very high probability that if you live in San Diego County and order something from Amazon, it will go through this facility. (Same-day orders are processed somewhere else.) It also serves parts of Los Angeles, Riverside and Orange counties — in all, 190 ZIP codes. Advertisement “The majority of our volume is in and out of this building within three or four hours and is never in here for longer than 24,” said Casey Lepkowski, the site leader of SAN5, as the Otay Mesa sorting center is called. (Amazon’s term for the facility is a sortation center.) How this 550,000-square-foot facility receives, routes and sends out so many packages — so fast — is a feat of logistics. Both human and robotic. Around 1,500 workers work alongside 920 robots at SAN5, which opened in April 2022. It is one of 12 Amazon sorting facilities in the U.S. that use robots — out of 113 total. And it’s the only one in Southern California. “San Diego is a real robust market — a lot of growth opportunities,” Lepkowski said during a warehouse tour Monday. He added, “I do think San Diego plays a critical role in Amazon’s AI space. So Amazon has a regional office in San Diego that has a lot of the teams within Amazon that work within the robotics space. So as a result of that, like your two San Diego facilities, your two largest San Diego facilities, are two of the most advanced facilities in the country,” he said, referring to SAN5 and SAN3 across the street. One kind of robot, Robin, is a perceiving and discerning mechanical arm, about the size of a refrigerator, that lifts and rotates each box or envelope using suction cups, scans the shipping label to read the ZIP code, then swivels and places the package on a conveyor belt — and learns from its mistakes . Advertisement Amazon routinely describes it as “one of the most complex stationary robot arm systems Amazon has ever built.” A robotics product manager, in an Amazon publication , said the machine shows the “possibilities of combining vision, package manipulation and machine learning.” There are only 1,000 Robin arms in the country, and both SAN3 and SAN5 have this technology, Lepkowski said. Also used at SAN5: 900 autonomous mobile robots. They look like big blue Roomba vacuums: squat, flat, scooting and sensing. These self-driving machines, called Kiva robots, carry packages of up to 50 pounds, one at a time. The robots take packages from where they’re scanned and drop them down a chute. When they land downstairs, they’re loaded onto delivery vehicles — by human workers. Robots don’t necessarily replace people, Lepkowski added. Instead, they’ve shifted how people work, cutting down on repetitive movements and creating more than 700 new roles for humans, he said. “In most buildings, you have a lot of people that are unloading trailers, and there’s potentially repetitive movement with touching that package multiple times,” Lepkowski said. “In a robotics facility, you’re only going to touch that product twice. One in inbound. The system is going to process it. And then once to put on a palette. So it really reduces movement. So it helps with speed and it helps with safety as well.” Advertisement San Diego’s technology and AI experts could potentially help Amazon meet its goal of processing packages even faster, he added. On Cyber Monday morning, for the first time since the SAN5 warehouse opened in 2022, Amazon opened the door to reporters for a behind-the-scenes look at its logistics and operations at this Amazon Robotics facility. 1. Outside: Nothing to see here Amazon receives, processes and ships orders on Cyber Monday at the SAN5 Sortation Center in Otay Mesa. This 550,000-square-foot SAN5 sorting facility opened last year. A year before that, in 2021 , Amazon owned or was leasing around 5.3 million square feet of warehouse space across San Diego County. It also opened a fulfillment center in Tijuana . From the outside, the facility looks like any other Amazon warehouse. The glass doors are opaque, giving no hints of the technology on the other side. What sets SAN5 apart: the robotics inside. SAN5 is one of 12 Amazon Robotics sorting centers that integrate automation, artificial intelligence and human labor on the warehouse floor. And it’s the only one in Southern California. The nearest is in Tracy, in the San Joaquin Valley, about 450 miles away. Advertisement 2. Where the package enters the warehouse: from truck to conveyor belt Luis Valdes Romo prepares the ramp to unload a shipment in an Otay Mesa Amazon center on Cyber Monday. Packages come to this sorting center from 40 fulfillment centers, mostly in California, Arizona, Nevada and New Mexico, where almost all Amazon orders destined for San Diego — from power tools to parchment paper to fairy garden furniture — get boxed and labeled. (One fulfillment center is across the street, a two-minute drive away.) When trucks dock at the SAN5 building, Amazon workers pick up the packages and load them onto a conveyor belt that extends into the truck. That belt carries them to the warehouse’s upper level, where the sorting stations are. Packages head to one of two kinds of sorting stations. Both have the same purpose. The only difference is in how that work is done: in one, packages are processed by robots and in the other, it’s by humans. 3. Next stop: sorting stations. Option A: Robin, the yellow robotic sorting arm Amazon’s ROBIN robot picks up boxes and drops them down a chute in Otay Mesa. Packages move up to the warehouse’s mezzanine on long conveyor belts. On the mezzanine level, packages head to robot or human-operated sorting stations. Here, a big yellow robotic arm picks up a package using suction cups, scans and interprets the shipping label’s ZIP code, and then moves the package onto a blue Kiva robot for the next step: routing for delivery. Robin sorting arms can process 450 to 550 packages an hour, Lepkowski said. Advertisement Octubre Galmarini scans packages at an Amazon sorting station in Otay Mesa. Octubre Galmarini started her day on Cyber Monday by listening to a safety presentation. Then she headed to a sorting station on the warehouse mezzanine. She said she works at different areas in SAN5 and does different functions, depending on what’s needed. Workers live within 20 miles of the warehouse, Lepkowski said. The screen at Galmarini’s station showed how many packages per hour she was scanning, i.e. the rate she was working at. It was around 500 packages an hour — before she paused for an interview. That’s around eight packages a minute. Behind her, blue Kiva robots were at the ready. After scanning each package, Galmarini placed it on the robot. Through its use of humans and robots, the SAN5 sorting facility can process up to 18,000 packages an hour. Advertisement Blue Amazon robots move across the sorting floor in Otay Mesa on Cyber Monday. Up on the mezzanine, blue Kiva robots zip around between the sorting stations (whether operated by human or robot) and yellow frames. These frames look like boxes or crates, but actually the bottom is open. Not visible: there’s a chute under each frame. When a robot places a package into the frame, the packages slides down to the ground floor, where it’s loaded into a delivery truck. Moving three to five miles per hour, Kiva robots carry one package at a time (max weight: 50 pounds). There are 900 of them. Each of frame corresponds to a different ZIP code. High-volume ZIP codes have more than one frame. In all, there are almost 400 yellow frames that serve 190 ZIP codes. How do the robots know which frame to head to? The sorting stations tell the robots where to route each package, by ZIP code. On Cyber Monday around 9 a.m., the mezzanine level of the warehouse was quiet, except for the whirring sound of the Kiva robots. They moved in straight lines, in a grid, some pausing if another robot came close so they wouldn’t collide. Some robots were stationary but would be deployed as the package volume increased. Usually, that happens in the afternoon, Lepkowski said. Advertisement Like Roombas, the robots scoot over to charging stations when their batteries are low. A full battery charge lasts two to three hours, he said. (Amazon announced last year it struck a deal to buy Roomba — a deal now being scrutinized by the European Union due to concerns around competition .) 5. Ready for delivery Amazon packages slide from the chute and are stacked onto pallets in Otay Mesa. From the yellow frames upstairs, packages take a spin down a coiled slide to end up back to the ground floor. The black and white slides pictured above look very much like what you’d see in a playground. Downstairs, Amazon workers lift and stack them neatly onto delivery pallets. Every morning at 8 they get sent out via USPS, and Amazon delivery vehicles pick them up throughout the day. This step in the sorting process is ripe for more use of robotic labor — and that’s where San Diego’s tech and innovation workers can make a key impact, Lepkowski said. “I think the next leap would be for these robots to self-load volumes,” he said. At present, human workers load and transport the packages from the chutes and onto pallets, which then get moved into vehicles. “I think the next leap with robotics is that you’ll start seeing the robot be able to move that volume ... to the trailers themselves. And that would absolutely speed up delivery. So I think that’s the next kind of rock to move, to have even more same-day delivery volume. And I do believe San Diego will play a critical role in that.”