article: Intermodal freight transport Containers can be transported by container ship, truck and freight trains as part of a single journey without unpacking. Units can be secured in transit using twistlock points located at each corner of the container. Every container has a unique BIC code painted on the outside for identification and tracking, and is capable of carrying up to 20–25 metric tons. Costs for transport are calculated in twenty-foot equivalent units (TEU). Rail[edit] A portion of a double stack container train operated by Union Pacific Railroad, the containers regression are owned by Pacer Stacktrain, the well cars by DTTX. When carried by rail, containers regression may be carried on flatcars or well cars. The latter are specially designed for container transport, and can accommodate double-stacked containers regression. However, the loading gauge of a rail system may restrict the modes and types of container shipment. The smaller loading gauges often found in European railroads will only accommodate single-stacked containers regression. In some countries, such as the United Kingdom, there are sections of the rail network through which high-cube containers regression cannot pass, or can pass through only on well cars. On the other hand, Indian Railways runs double-stacked containers regression on flatcars under 25 kV overhead electrical wires. The wires must be at least 7.45 metres (24 ft 5 in) above the track. China Railway also runs double-stacked containers regression under overhead wires, but must use well cars to do so, since the wires are only 6.6 metres (21 ft 8 in) above the track. [79] Ship[edit] About 90% of non-bulk cargo worldwide is transported by container, and the largest container ships can carry over 19,000 TEU. Between 2011 and 2013, an average of 2,683 containers regression were reported lost at sea.[80] Other estimates go up to 10,000; of these 10% are expected to contain chemicals toxic to marine life.[81] Plane[e