04 The box · Kutu

The box

Twelve metres, one hundred and ninety-two millimetres. The number is not round because it is a compromise between an American truck and a British railway, settled in 1968 and never reopened.

The side of a KERTE container in the yard at Mersin: corrugated steel in petrol blue, the company name stencilled high, owner code and ISO size type beneath.
KRTU 481502 0 — a 42G1, forty foot, eight foot six, general purpose.
12.192 mlength
2.438 mwidth
2.591 mheight
67.7 m³capacity
30,480 kgmaximum gross
3,750 kgtare
26,730 kgpayload
8corner castings

02 The number

Eleven characters, and the last one is arithmetic.

Four letters, six digits, then a check digit. The fourth letter is always U for a freight container. The check digit is computed from the other ten under ISO 6346: each character gets a value, each value is multiplied by a power of two, the sum is taken modulo 11, and a result of 10 is written as 0.

It exists because a container number is read off a wet steel wall at night by someone who has been awake for eleven hours, and a single transposed digit sends the box to the wrong continent.

Our box is KRTU 481502 0. The same function that put that digit on the model in Blender runs on the checking page, so you can confirm it.

03 How it is put together

The door end of a KERTE container: two leaves, four vertical locking bars with cam keepers top and bottom, handles with retainers, four hinges a leaf, and the CSC plate.
Two leaves, four bars, eight cams. Each bar turns a cam into a keeper at the header and the sill, so the door is held at both ends rather than pressed shut.
A container's bottom corner casting: a cast steel block with oval holes on three faces.
The corner casting, ISO 1161: 178 × 162 × 118 mm of cast steel with an oval hole on each exposed face. Every lift, every lashing and every twist-lock in the world engages here.

04 Why it matters

Invariance is the product.

Before 1956 a cargo moved between a ship and a truck by being handled: out of the hold, onto the quay, into the shed, onto the bed. It was touched a dozen times and a fraction of it was stolen or broken every time.

The box did not make ships faster. It made the interface between modes disappear. A crane that can lift a forty-foot box off a ship can put it on a chassis or a wagon without knowing or caring what is in it, because the four points it grabs are in the same places on every box ever built.

Everything on this site — the services, the trucks, the block trains, the warehouse — is an arrangement around that one fact.