Other, more specialized marine containers are available in the market, including open-top containers, refrigerated containers and tank containers for liquid product. The second type of container commonly used on Canada's rail and highway system is the domestic intermodal container. This container is designed to maximize payload on the domestic transportation system. They are longer than marine containers, ranging from 45 to 53 feet in length, and are not designed for use on ocean vessels. When marine containers are scarce at inland points, or when transporting relatively low value goods that can be moved more efficiently in longer equipment with higher payloads, it is common for a domestic intermodal container or a standard highway trailer to be loaded at an inland point, moved by rail or truck to port, and the contents transloaded to a marine container at port.
China is one of the world's leading, low- cost manufacturers of containers.
In addition, many container operators lease containers from one of numerous companies that specialize in container leasing. The typical 20 foot dry container has a rated payload capacity of 21.8 tonnes, or 32 cubic metres. When loading a grain product in bulk into this type of container, allowance must be made for the insertion of temporary grain doors and the need for adequate space to manoeuvre a bulk conveyer over the doors. Consequently, the average bulk payload in a 20 foot container of a commodity with the density of trapper peas would be about 20 tonnes. There are two basic functions performed at these ports with respect to marine container traffic.