Maritime shipping lines offer scheduled services commonly organized as loops calling ports along several maritime ranges that eventually end at the ‘starting port’, which is usually the port that generates the largest amount of export cargo. To maintain fixed call days, shipping lines usually employ what is colloquially called the “Rule of 7: The number of vessels in a rotation is a multiple of 7. So a rotation of 28 days would employ 4 vessels while a rotation of 56 days would employ 8 vessels.
The world’s largest container shipping line, Maersk, maintains several inter-range services servicing the world’s major freight markets. The three main serviced markets are Western Europe (Atlantic and Mediterranean facades), North America (Atlantic and Pacific Facades), and Pacific Asia (mainly China’s main coastal ports). Each is serviced by a series of port calls where containers are transshipped to offshore hubs or to hinterlands, depending on the function of the port and the destination of the cargo. The time it takes to complete a full loop is a function of the nautical distance involved as well as the number of ports called. Transatlantic loops tend to be shorter (about 32 days for the TA2 service), while Asia-Europe loops are among the longest (73 days for AE11).
The itinerary of inter-range service is carefully selected to ensure distribution strategies that reflect the global and regional trade framework. Ports of call usually involve a combination of gateways and transshipment hubs. For instance, several Mediterranean port calls of the AE11, such as Port Said and Gioia Tauro, are major transshipment hubs. For the United States, cabotage regulations (Jones Act) forbid a foreign-owned maritime shipper to carry traffic between American ports, so port calls are at major gateways. Also, high capacity ships can be used for inter-range services (such as across the Pacific), supporting the profitability of long-distance shipping. Express services are also offered