“…Ports are often classified according to their operational differences, such as the dominant commodity handled (Bichou and Gray, 2005), which is an essential element of their activity. The contemporary specialization of maritime transport and port operations resulted in a variety of local combinations, each port handling a different set of commodities, from the most specialized to the most diversified, with many ports becoming redundant for a few large gateways concentrating all kinds of traffics (Mayer, 1973;Von Schirach-Szmigiel, 1973).…”