Freight railroads and passenger rail service
The vast majority of the 22,000 or so miles over which Amtrak operates are actually owned by freight railroads. By law, freight railroads must grant Amtrak access to their track upon request. Amtrak pays fees to freight railroads to cover the incremental costs of Amtrak's use of freight railroad tracks.
A freight train is a group of freight cars hauled by one or more locomotives on a railway, ultimately transporting cargo between two points as part of the logistics chain. Trains may haul bulk material, intermodal containers, general freight or specialized freight in purpose-designed cars.
The main disadvantage of rail freight is its lack of flexibility. For this reason, rail has lost much of the freight business to road transport. Many governments are now trying to encourage more freight onto trains, because of the environmental benefits that it would bring.
Railroad companies in the United States are generally separated into three categories based on their annual revenues:
- Class I for freight railroads with annual operating revenues above $346.8 million (2006 dollars)
- Class II for freight railroads with revenues between $27.8 million and $346.7 million in 2006 dollars
- Class III for all other freight railroads including local line haul railroads, or shortlines, that operate less than 350 miles and earn less than $40 million per year (most earn less than $5 million per year). They generally perform point-to-point service over short distances.
These classifications are set by the Surface Transportation Board.
Containerization is a system of intermodal freight cargo transport using standard shipping containers (also known as 'ISO containers' or 'isotainers') that can be loaded and sealed intact onto container ships, railroad cars, planes, and trucks. Containerization has revolutionized cargo shipping. Today, approximately 90% of non-bulk cargo worldwide moves by containers stacked on transport ships; 26% of all containers originate from China. As of 2005, some 18 million total containers make over 200 million trips per year.
Most flatcars (US) cannot carry more than one standard 40 foot container on top of another because of limited vertical clearance, even though they usually can carry the weight of two. Carrying half the possible weight is inefficient. But if the rail line has been built with sufficient vertical clearance, a double-stack car can accept a container and still leave enough clearance for another container on top. This usually precludes operation of double-stacked wagons on lines with overhead electric wiring.
Bulk cargo is commodity cargo that is transported unpackaged in large quantities. Cargo is usually dropped or poured, with a spout or shovel bucket, as a liquid or solid, into a bulk carrier's hold, railroad car, or tanker truck/trailer/semi-trailer body. Bulk cargoes are classified as liquid or dry, but only the latter are normally transported as bulk on rail, the former being freighted in tank cars.
Hopper cars are freight cars used to transport loose bulk commodities such as coal, ore, grain, track ballast, and the like. This type of car has opening doors on the underside or on the sides to discharge its cargo. There are two main types of hopper car: open and covered; Covered hopper cars are used for cargo that must be protected from the elements (chiefly rain) such as grain, sugar, and fertilizer. Open cars are used for commodities such as coal, which can get wet and dry out with less harmful effect.
Several types of cargo are not suited for containerization or bulk; these are transported in special cars custom designed for the cargo.
- Automobiles are stacked in open or closed autoracks, the vehicles being driven on or off the carriers.
- Steel plates are transported in modified gondolas called coil cars.
- Goods that require certain temperatures during transportation can be transported in refrigerator cars, but refrigerated containers are becoming more dominant.
- Liquids, such as petroleum, chemicals and gases, are often transported in tank cars.
Intermodal freight transport involves the transportation of freight in an intermodal container or vehicle, using multiple modes of transportation (rail, ship, and truck), without any handling of the freight itself when changing modes. This method reduces cargo handling, and so improves security, reduces damages and losses, and allows freight to be transported faster.