With a single mode (road), a gateway services its hinterland through a capillary / tree like structure where flows converge at the terminals (A). In time, many transport terminals have become surrounded by various economic activities, many of them freight related, which poses challenges in terms of local and regional road access. Congestion increases and terminal access becomes increasingly problematic, which may negatively impact the efficiency and reliability of regional freight distribution. This problem is compounded if the terminal is surrounded by a large metropolitan area, as most ports are. Port-related circulation conflicts with the circulation of other urban activities. To cope with a growing level of congestion which undermines the reliability of freight distribution as well as imposing additional costs and delays, two interdependent strategies can be implemented (B):
- Modal shift. Involves a closer integration with an alternative transport mode with a share of the shipments entering or exiting the terminal through another mode, which commonly involves rail or barge shuttles. These modes are likely to be much less congested and convey better economies of scale. Still, this requires the setting of inland terminal facilities to act as load centers.
- Freight diversion. Satellite terminals enable the interception of freight shipments which instead of entering a congested metropolitan area is bound to terminals easier of access. The same rationale applies for outbound freight flows. This can also have the advantage of expanding the hinterland of the gateway, particularly since flows have an intermodal alternative.