The 20ft Shipping Container is no longer the main size used for international shipping but its still utilized as one of the standard ISO sizes. When talking about Twenty Foot Equivalent Unit (TEU) its often how the standard sizes are discussed in the shipping industry. The size may vary in length but will still be recognised as 1 TEU the only constant being the 8ft width as height can go from 4’ 3” to a high cube of 9’6” and even the volume space would not make a difference to the terminology of it still being 1 TEU. Once it gets over 40ft in length however it suddenly becomes 2 TEU in size part of the imperial measurement system. Odd thing is with a container being of 40ft or more it becomes rated as a Fourty Equivalent Units (FEU). May seem a bit odd but it came down to War and a standard “estimated” size had to be implemented because there were too many variables on things being moved by the military that one size fits all simply didn’t work but getting a system as close to was needed and its why the FEU and TEU exist today.
Gross mass maximum rating on a 20ft shipping container is 24,000kg and a 40ft container is 30,480kg regardless of height.]
Payload Maximum weights are 21,600kg for 20ft and 26,500 for the 40ft.
The 20ft shipping container was the standard unit size used by Matson and other shipping companies as it was convenient size for goods shipped between the West coast of the United States and Hawaii. More importantly they sat inside the converted World War II C-3 cargo ships Matson used for many years. It was however in 1957 that Matson then decided to start using containers at 25ft as this maximised his transportation potential for his purposes. His freighters could then transport the units six high inside the cargo holds and on the top deck of the freighters. For trucking purposes a 20ft shipping container was too short as loading two of them onto a bed often would break road weight limitations meaning the trucks could only haul one 20ft at a time. The optimal size for a single bed truck is 24 – 27ft in length.
In todays world we see shipping containers of up to 48 and 53 feet in length which are popular for international shipping as loading time for 20ft takes just as long as a larger shipping container but obviously takes twice as long to load a ship, time is money and why many 20ft shipping containers are being abandoned for the larger units as its not economically viable to use in comparison to the larger containers or in fact the improved road structures we see today that allow easier freight transportation.
20ft shipping containers are still available and are even still being manufactured, yet its the bigger shipping containers that are mainly used due to the reasons above.