Inside an Amazon Fulfilment Centre

Amazon LTN4 in Dunstable

On Bank Holiday Monday my family and I visited our local Amazon fulfilment centre for a factory tour. It was an eye into the future of robotic automation, and an opportunity to see how something as traditional warehouse stock picking can be reinvented from the ground up.

We visited LTN4, which is in Dunstable (near Luton, Hertfordshire) in the UK. Amazon fulfilment centres are named after their nearest airport codes (Luton airport is less than 10 miles away), and we visited the 4th building on the industrial estate.

From the moment you arrive at the car park, safety is a priority. There are signs every few metres instructing drivers to reverse into spaces.

Inside the warehouse, there are safety signs everywhere. The second priority is security. Employees and visitors need to leave everything except keys, wallet and phone in a locker. There are hundreds of lockers for the 1,200 permanent staff. And there’s even an Amazon locker in the reception area. There are airport-style metal detectors which all staff need to pass through on the way in and out of the warehouse.

Once on the tour, we watched the stock fillers, stock pickers, and two sets of packing teams – for customers who ordered a single item, and on the opposite side of the warehouse, pickers for customers with multiple items. We weren’t allowed to take any photos during the tour, except in the room below.

Stock filling

A decommissioned Amazon Robot

Amazon’s approach to laying out the stock in the warehouse is not just unconventional. It’s revolutionary.

The majority of the warehouse is a caged area, filled with 2 metre high, four-sided, multi-shelved yellow units called pods. The pods have elastic tape around the perimeter, keeping items from falling out. There are a few people standing at platforms on the perimeter of the cage, either filling stock or picking it.

Items arrive at the warehouse and a stock packing person labels individual items, or even a pack of smaller items with a QR code. They then scan the code and place it on a shelf on the pod, wherever there is space. At this point the packer then scans another code on the shelf. This has told the stock computer that a specific item is on a specific shelf on a specific pod.

The item might be a single book among other random stock, or a pack of notepads among many other random items. And they are totally random – similar items are kept apart, to stop the wrong item from being picked later.

Once this is done, an Amazon robot, which is the same footprint as the pod, picks the entire pod up and moves it elsewhere in the warehouse. The packer then turns to take the next item to be stocked, and by the time they’ve picked the item up and turned around, another robot has brought another pod.

Stock picking

It’s easy to imagine the stock pickers, collecting customer orders, running around the warehouse. But the opposite is true.

Pickers stand still. An Amazon robot brings the correct pod across to the picker, who has a screen on their left showing the next item to be picked, from a given shelf. The screen clearly shows a photo of the item too. Once the picker has taken it from a shelf (a couple of seconds), they scan the code on the item, which tells the picker if the correct item has been selected. Our tour guide said mistakes are very rare, “I might have picked the wrong item once a week” she said.

The items are placed in a black plastic box, which then joins a conveyor belt running around the warehouse, about 4 metres high. We were in the 4th building in Luton, and there were 3 floors in just this building.

Once items are picked from a pod, the pod is whisked away, a new pod arrives, and a new item appears on the screen.


The black boxes are then sent to a packer, who is told which size box or envelope (or none at all) to use. With more labels and more scanning, the error rates are very low.

Wrapped items are then put on another conveyor belt where an address label is stuck to the parcel. Every packed item on the conveyor belt were totally uniform, with the Amazon smile pointing the same way and none were upside down.

Customer first

Inside the large caged area of the warehouse are thousands of pods moving around, being transported by the Amazon robots. Some are being sent to be packed with more stock and some to be picked for customer orders. There are no people inside the cage. When two robots want to go the same way, the one who is about to fulfil a customer order has right of way over a pod to be restocked.

Out of stock

The picking process is so efficient, and yet constantly being tweaked. A week before we arrived, the system had been upgraded to allow multiple, same items being stored on the same shelf.

If a customer orders multiple items from Amazon in one order, but Luton doesn’t have all the items, Amazon will ship remaining items from other fulfilment centres to Luton. One these items are transported from say, Manchester, they are stocked in a pod as usual, until the full order is available from Luton, and then they are picked.

Thinking beyond retail

The tour was eye opening, to show what can be achieved through robotic automation and people together. There are 2,000 Amazon robots on site, recharging themselves when necessary. Amazon still needs 1,200 people to pick items.

A friend who works for Amazon’s AWS (Web Services) division comments how everything, everything, within Amazon’s data centres and support needs to be automated. His teams must not use manual processes – they have to script them from the start in an easily  repeatable way.

During the factory tour, I kept thinking about other industries, such as banking, or insurance, which are struggling to implement automated processes – and they don’t have usually have anything physical to move around like Amazon does.

You can book a tour of an Amazon fulfilment centre here.

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