Sources: Port TEU figures from port authorities and port associations. Air cargo figures from Airports Council International.
The global gateways index is the weighted sum of the global share of the container and air cargo traffic of a metropolitan area. It considers a sample of 198 cities that are either having significant container or air cargo traffic. The weight attributed to the container and air cargo components is related to their share of the value of global trade (85% and 15%, respectively). A metropolitan area having a share of 1.5% and 0.8% of the global container and air cargo throughput (as handled by its container ports and airports) will have a global gateways index of 1.395 (1.5 * 0.85 + 0.8 * 0.15).
The global system of freight circulation is articulated by major gateways that are composed of a cluster of port and airport terminals within a metropolitan area. This does not mean that ports and airports are functionally integrated (they are not), but that the region they service is a major load center serviced by a variety of globally oriented supply chains, some using the ports while others are using the airports. The global gateways index represents the relative importance of a metropolitan area in the global container and air cargo transport system; two long-distance trade modes. The index does not include crossborder traffic, which would make cities such as Detroit rank much higher. Global gateways show a high concentration level, with the 25 largest gateways accounting for an index of 50% of the containerized and air freight activity and the 50 largest gateways with an index of 65%.
Gateway regions are groupings of gateways that are organized along a major corridor. The most important gateway region is the Pearl River Delta (Hong Kong, Shenzhen, and Guangzhou), with a combined index of 10.5% of all the world’s containerized and air cargo freight. Other significant gateway systems concern the Yangtze River Delta (8.4%), the Strait of Malacca (Singapore, 7.6%), the Rhine / Scheldt delta for Western Europe (e.g. Antwerp, Rotterdam, 3.9%), and Southern California (Los Angeles area, 2.6%) for the American West Coast. There are significant variations in the modal composition (and importance) of the gateways. While in most cases, containerized traffic dominates the gateway function, air cargo carries a high share in gateways such as Dubai, Seoul, and Bangkok. Each of these is a major air cargo hub with an adjacent concentration of high-tech industries.