Inter-range maritime services involve a set of sequential port calls along a maritime range, commonly including a transoceanic service to ports in another range and structured as a continuous loop. They are almost exclusively used for container shipping with the purpose of servicing a market by balancing the number of port calls and the frequency of services. For instance, inter-range services between Asia and Europe have on average 8 to 10 containerships assigned involving 8 to 12 port calls. A service between Asia and the US West Coast would have 5 to 7 ships. Most transatlantic pendulum services have 6 to 8 containerships and involve 6 to 8 port calls.
An inter-range service is fairly flexible in terms of the selection of port calls, particularly on maritime ranges that have nearby and competing ports (e.g. North American East Coast, Western Europe). This implies that a maritime container shipping company may bypass one port to the advantage of another if its efficiency is not satisfactory and if its hinterland access is problematic. The shipping network consequently adapts to reflect changes in market conditions. The structure of inter-range service networks can take many shapes depending on factors such as the markets being serviced, trade imbalances, and regulations:
- Symmetrical. Inter-range routes that involve a similar number of port calls on the maritime facades serviced. Such a structure offers a good level of market coverage if the number of allocated vessels is sufficient, but with the drawback of longer cycle times.
- Asymmetrical. Involves fewer port calls along one of the maritime facades serviced. This reflects several situations, including trade imbalances, market concentration, cabotage constraints, or export-oriented strategies. For instance, a maritime shipping company would be reluctant to offer several port calls along a facade within the same country (such as the United States) if cabotage regulations are present. It won’t be able to carry domestic containers between ports of the same facade, only pick up or drop them off. Trade imbalances also reflect asymmetrical inter-range services as traffic is collected along one facade and unloaded on the other range at a few major gateways accessing inland corridors.
- Inter-hub. These services are almost similar to charter services as they directly connect major hubs or gateways. Their advantages are high capacity and frequency as well as lower cycle time, which can be offered when there is a substantial demand between the few ports serviced. They tend to involve the largest containerships available.