Which material is commonly used for constructing modern shipping containers?

Steel is commonly used for constructing modern shipping containers due to its strength, durability, and resistance to harsh marine environments. Steel containers can withstand the stresses of stacking and handling during transport, making them ideal for intermodal freight, where they can be seamlessly transferred between ships, trucks, and trains. The use of steel also allows for standardization in size and structural integrity, which facilitates efficient loading, unloading, and storage.

Wood, while historically used for shipping crates, lacks the durability and resistance to weather elements that steel offers for long-term marine use. Plastic containers, although lightweight and resistant to some corrosion, do not provide the same level of security and strength needed for heavy cargo shipments. Copper, on the other hand, is not a practical choice for container construction due to its high cost and potential for corrosion in marine environments.