I confess that I don’t pay a lot of attention to shipping containers. When two miles of double stacked containers roll by, my eyes glaze over a bit and I don’t look at individual containers. There are just too many and most are fairly generic.
Sometimes, one catches the eye.
I was watching a CN train departing Winnipeg on the Sprague subdivision at Navin when I spotted this CMA CGM container. The container itself is unremarkable – your basic 40′ can, painted in unassuming blue – but the lettering caught my eye.
“eco container bamboo flooring”
Bamboo flooring? Containers have floors? And why bamboo?
Off to the
Google machine DuckDuckGo machine to do some searching.
Shipping Container Structure
A shipping container is almost always made of steel, and is a basic steel box in various standard lengths (20′, 40′, 45′, 48′, 53′ and new 60′ containers). The height and width is standardized so you can stack many containers together interchangeably. There are locks on the corners so that you can lock stacks together for additional strength.
Container capacity is measured in TEUs, Twenty-foot Equivalent Units.
- 20′ container = 1 TEU
- 40′ container = 2 TEU
- 45′ container = 2.25 TEU
- 48′ container = 2.4 TEU
- 53′ container = 2.65 TEU
- 60′ container = 3 TEU
Inside the container, there are steel cross-members reinforcing the four sides of the container, spaced every 4 to 6 inches, and they are about 5 inches high. You can imagine that it’s hard to pile material in a container on top of these cross-members, so you need a floor.
Traditional Container Floors
Traditionally, container floors have been made of marine-grade plywood. As you probably know, plywood is made of several thin layers of wood sandwiched together with glue to provide additional strength.
Marine plywood is treated to be waterproof and insect proof.
This page has some great photos showing the inside of a container and the flooring.
Containers can hold more than 60,000 lbs., so you need a good strong floor. Marine-grade plywood has provided that. It’s also used in truck trailer flooring and many other applications.
So What’s the Problem?
Marine grade plywood is usually made with tropical wood – apitong trees in particular. These trees were common in the Philippines and found in Borneo, Indonesia and other south Asian countries. It is often known as “keruing” in shipping applications.
The problem is that so much of this tropical wood has been harvested that it has become a big environmental problem. I’m sure you’ve heard of Amazon rainforests being cleared, and although shipping container floors aren’t the only source of the problem, they are part of the problem.
Several alternatives to marine-grade plywood floors have emerged: recycled plastic, composite floors, thin steel floors and bamboo floors.
This article discusses some of the alternatives.
You need a floor that doesn’t add a lot of weight to the container, has the same dimensions as the traditional floor, and lasts a long time.
Bamboo has emerged as a strong contender because bamboo grows very quickly – a bamboo tree grows to maturity in three to five years – and it is biodegradable.
You can tell that CGA CGM is proud of their bamboo floors! Their web site says that 11% of their containers use bamboo flooring. Considering that they have more than 4 million TEUs of containers, that’s a lot of containers!
Maersk, the giant Danish shipping line, has required the flooring of new containers to be made of responsibly sourced flooring since 2011.
Other shipping companies like OOCL have started using bamboo floors as well.
It’s a start.
I know I’ll be keeping a closer eye on containers in the future, looking for interesting things like these bamboo-floor containers!
Just One More Thing
If you’re interested in learning more about shipping containers, I highly recommend The Box by Mark Levinson. This book goes into the history of shipping, and the development of shipping containers to solve the many issues with traditional break bulk shipping. It’s a lot more interesting than it sounds! (I wrote a review of the book a few years ago)