Since freight terminals act as buffers between different systems of circulation, a notable amount of inventory can be found at terminals at any given time. Occasionally, the inventory remains for a short duration (a few days of dwell time for high turnover terminals), but terminals can perform a storage function for several weeks and longer for bulk cargo. Irrespective, the inventory is considered to be in transit, but stored at the terminal. Six major categories of inventory in transit can be considered according to the type of freight and load unit:
- Containers (stacked). Most container terminal facilities store containers as piles that are handled using specialized equipment such as reach stackers, straddle carriers, and gantries. This is particularly the case for ports where container yards act as a buffer between maritime and inland systems of circulation. It is possible for cargo owners to use container yards as a temporary warehouse, particularly if the terminal offers free or low-cost dwell time.
- Containers (chassis). Several rail terminal facilities and occasionally ports, store their container inventories on chassis. This allows for a quick drop-off and retrieval for drayage but has a much lower density than a stacked container yard. The advantage of chassis is that containers can be stored at a variety of facilities, including rail yards and distribution centers.
- Vehicles. Trading vehicles, mostly internationally, requires a substantial terminal footprint as vehicles need to be parked as they are rolled on and rolled off from a vehicle carrier. On the import side, once the vehicle has been readied and at times customized, it can be delivered to dealerships directly by truck or through rail.
- Dry bulk. Due to their ponderous nature, raw materials such as iron ore, coal, and fertilizers are stocked in piles adjacent to terminal facilities. This inventory can be traded and shipped to points of demand.
- Liquid bulk. Similar to dry bulk, the storage of liquid bulk is ponderous and requires storage tanks for different products and grades (crude oil. chemicals, vegetable oils, fertilizers).
- Neo bulk. Various types of cargoes such as construction materials and project cargo (e.g. windmills), that need to be handled with specialized gears. While waiting to be sent to the point of use, terminal facilities can be used for storage and even for repair and assembly.