Note: Although the above map relates to a real port complex, the geofences depicted are fictitious.
Geofencing creates virtual boundaries that act as notification events when they are crossed. To do so, location and status data of mobile assets (e.g., ships, trucks, containers) must be collected in real-time by a platform, which cross-reference these locations with set virtual boundaries. Once one of these boundaries is crossed, a log and notification are generated. Geofencing boundaries are commonly points, lines, or polygons. For points, geofencing is usually expressed as a radius from a defined coordinate. Lines involve at least two connected points that can be used to geofence a well-defined corridor, such as a channel, a terminal gate, or a road. Polygons enclose a defined area that can be a jurisdiction or a complex facility, which allows to define if an asset is inside or outside more clearly.
Geofencing can be used at several scales and for several functions. On the above map, a port complex can have several geofences used for different purposes. The port area (polygon) can be enclosed by a geofence, allowing to know with AIS data if a ship has entered or exited. Individual terminals can also be geofenced, giving a better level of precision about ship performance, including turnaround time. Specific facilities, such as warehouses or depots (polygons), can be geofenced to track cargo or empty containers. Another type concerns preset boundaries (lines), such as strategic road locations that can monitor traffic and truck turnaround time. The decision to set geofencing boundaries is related to the specific information needs of shipping lines, terminal operators, cargo owners, and port managers.