The background noise in Amazon’s warehouse is loud enough that tour guides must use headsets to talk to visitors.

When it opened in 2014 the Amazon warehouse on Canton Way in Robbinsville instantly became the town’s largest employer and became one of the biggest private companies in the county with its 3,500 workers.

Despite its importance, it was hard to know exactly what it was like inside the facility without asking someone who worked there. The company has recently taken steps to become more transparent. This year, Amazon began offering tours of its warehouses—“fulfillment centers” in company parlance—to the public. U.S. 1 joined one such public tour of the facility on a recent September morning.

The walk through the warehouse was led by Kate Pielli of Old Bridge, who worked her way up to tour guide after starting as an entry-level associate. Pielli, who recently celebrated her fourth “Amaversary” of employment, asked not to be quoted for the story. Like a number of other employees in the facility that day, she was wearing pajamas as part of a childhood cancer treatment fundraiser.

Amazon’s 75 fulfillment centers in North America are all named after nearby airports. Robbinsville is dubbed EWR4 for Newark International. (Customers can see which distribution center their packages came from by looking at that airport code.)

The warehouse is a massive, fast-moving machine whose purpose it is to sort, package, and send items on their way to customers. The 1.2-million-square-foot facility is highly efficient at this task: it sometimes takes less than an hour for an item to make its way from the loading dock where it enters the building to leave on a truck headed for a “sortation center” to be loaded onto a delivery van, and from there, a customer’s doorstep.

The first impression a visitor receives of the warehouse is its massive size. Volumes of this size are often described in terms of football fields by journalistic convention, and the facility is the size of 21 of them. It’s also loud — some of the employees were wearing ear protection, which Amazon provides for free, along with gloves, from vending machines that are unlocked with the swipe of an employee ID badge. The tour guide could only be heard with the aid of headsets worn by all the warehouse tourists.

Part of the warehouse looks like what you might expect a warehouse to look like: items stacked stories high on massive shelves. This area, closed to the public tour, is where bestselling items are stocked. But Amazon didn’t become the country’s third-largest retailer by selling only popular items. Instead, it’s the “everything store,” where customers can order almost anything imaginable from either Amazon itself or from third-party sellers.

Those odd items are the ones that flood in by the truckload, sometimes from other fulfillment centers and sometimes from manufacturers or sellers. With these items, the idea of a warehouse is reversed: instead of employees finding items on shelves, the shelves go to the workers, carried on the backs of robots (think an oversized Roomba) to workstations where workers place items on shelves and later remove them for packing. These robots travel inside a giant cage, their movements guided by bar codes on the floor.

Amazon has been expanding its use of robotics and now uses 100,000 robots throughout its facilities. In 2012 it acquired robotics maker Kiva and renamed it Amazon Robotics, so it could develop machines specifically to suit the company.

At the Robbinsville warehouse the power of automation is on full display. Computers determine the course of and track the progress of every single item that goes through the warehouse. After a box is unpacked, a worker scans its barcode, and an algorithm finds shelf space for it. It arrives at a sorting station, where a screen tells a worker which shelf to put each item on. There is no apparent rhyme or reason to the placement other than size: a jar of mustard might be next to a school textbook and a can of dog food. The system is called “chaotic stowing.” (As a robotics facility, EWR4 only handles small items that can fit on the robot shelves. Larger goods are routed to other fulfillment centers.)

The flat robots with shelves on their backs are not the only automatons at work. Elsewhere, self-driving vehicles carry stacks of flattened cardboard boxes, or the ubiquitous yellow totes that are used to transport items from place to place. The vehicles travel along pre-defined marked paths through the warehouse. They use turn signals and stop at crosswalks and can stop automatically if someone is in the way.

At a picking station a worker takes items off the shelves and puts them in yellow totes that go onto a conveyor belt. The tour stopped to observe a “picker” at work. A shelf rolled up to his workstation and a light shone on the shelf where his target was located while an image of the product flashed on a computer screen. He reached into the bin, found the item he needed out of the chaotic assortment of goods, scanned it, and placed it in a bin marked by a green light, then shoved the bin onto a conveyor belt to continue its journey.

Each shelf unit had two or three items for him to retrieve, then it would move away and another would approach immediately, with several more item requests. The pace was relentless: the worker was in constant motion throughout the few minutes we looked at him. There was never a time where he wasn’t performing a task.

The workers are assisted in their tasks by labor-saving machinery that automates as much as possible. About 14 miles of conveyor belts do much of the moving of devices. At a packing station a computer-automated dispenser doles out rolls of tape cut to the perfect length, taking away the guesswork of packing boxes. Box sizes are also automatically determined based on the description provided by the manufacturer, and errors here sometimes result in a small item being packed inside a comically large box.

Packages with some sort of problem, such as an inconsistency between expected and measured weight at some point along the line, are shunted off to the side to receive some human troubleshooting attention — packages designated for same-day delivery get attended to first. This is one job, requiring judgment, that is unlikely to be automated away no matter how advanced Amazon’s robots get. Another is quality control, where workers check for damage, mismatched descriptions, and other problems.

Later on the conveyor belt, Scan, Label, Apply, and Manifest machines finish readying the packages. One machine shoots delivery labels onto boxes with puffs of air. Finally, as they pass by the loading area at the opposite side of the warehouse from where they came in, plates shove boxes into chutes leading to the correct loading area, where workers stack them onto trucks.

By the time it leaves the warehouse, each package will have been handled by several people, but only for a few seconds at a time. In 2016 the company told CNN Business that between taking an item off the shelf, boxing, and shipping it, each item took about one minute total of human labor, with the rest of the work being done by robots and automated systems.

All this automation helps Amazon provide the free two-day delivery that Amazon Prime members have come to expect. Somewhat counter-intuitively, Amazon has added workers even as it has increased automation because the number of orders has increased dramatically and along with it the need for labor. The efficiency of the process is a definite boon to consumers, but something of a double-edge sword: many of the non-robot tasks remaining to low-level workers are repetitious by their nature. Some workers feel like they themselves are pushed hard and treated like machines.

This fast pace of work is at the core of criticism of working conditions at Amazon warehouses by labor advocates as well as current and former employees.

“We are humans, not robots!”

That’s what the employee-made signs said at a small demonstration staged last July on “Prime Day” at an Amazon warehouse in Minneapolis. By all accounts it was not a large walkout and didn’t seem to slow down the online retail company’s operations at all: The company sold more than 175 million items over the length of the two-day sale, breaking previous records. (The most recent labor demonstration at the Robbinsville location took place in December and was attended by union advocates and former employees but not current employees.)

In fall, 2018, Rutgers University’s Kairos magazine published an investigation of working conditions at Amazon and included an interview with Amanda Winckelman, a former picker at Robbinsville. She said the job was “very physically gruelling” and that “you do the same thing over and over again.”

A workday for an Amazon warehouse associate is governed by computer algorithms, which tell him or her where to put items, but also set a pace for how much work to do during the course of a shift. Those who fall behind are “coached” to improve performance or eventually are fired if they can’t meet the quotas.

Full-time Amazon employees, which comprise 95 percent of the EWR workforce, do 10-hour shifts with two 15-minute paid breaks and a half-hour unpaid lunch breaking up the workday. Overtime, paid at time-and-half, can extend that work-week even longer. There is a day shift and a night shift, with start times staggered to relieve traffic and parking problems. Seniority plays a role in which shift workers are put on, so new hires are likely to be on the night shift, with skilled veterans on duty during the day.

Amazon has also been criticized for workplace accidents. A report from the National Council for Occupational Safety and Health, a nonprofit group promoting workplace safety, said that 13 people have died working for Amazon since 2013, six of them in the seven months leading up to April, 2019.

Amazon’s direct employees are paid well for the industry. The company pays a minimum of $15 an hour to workers nationwide, requiring no education and no experience for many positions. In response to older complaints about working conditions, it has installed air conditioning in every one of its warehouses. Workers say the pay and benefits — such as health insurance and 401(k) contribution matching — are better than industry competitors and other entry-level jobs.

Amazon advertises $16.10 an hour minimum pay in commercials recruiting workers for the Robbinsville location. Many benefits kick in on day one, and after a year employees earn additional perks such as six weeks of paid maternity and paternity leave. Amazon also pays tuition for employees to attend community college as long as they are studying for a high-demand occupation such as nurse, paralegal, or pharmacy tech.

While Amazon does offer a stock ownership program for employees, the rise of the company has overwhelmingly benefitted those at the top. The company had $232.9 billion in sales in 2018, and the net worth of Amazon founder Jeff Bezos is estimated at $107.8 billion, making him one of the richest people on the planet. Amazon made more than $11 billion in profit in 2018 and paid no federal income tax.

Amazon is constantly recruiting new workers, especially during the rush to fill Christmas orders, when demand is at its peak. During the visit in September, the recruitment office where the tour kicked off had a line of new hires, and there were ads on job-seeking websites looking for entry-level associates as well as management positions.

To sign up for a tour, visit aboutamazon.com.