Overview#
A category-four hurricane is approaching a coastal region. Emergency managers need to establish an evacuation zone around the most exposed coastal strip, a shelter-in-place zone for areas further inland, and a search area for the bay where offshore vessels may be sheltering. All three boundaries need to appear on responder devices within minutes, track how many residents are affected, and expand automatically as storm surge projections worsen. The Geofencing domain handles the complete lifecycle of those boundaries: creation, activation, population estimation, auto-expansion, and the entry or exit notifications that fire when personnel or devices cross them.
This domain handles the more complex, operationally rich geofencing use cases: emergency management, public safety response, and critical infrastructure. Where the Geofence domain covers investigative surveillance boundaries, this domain covers population-scale event management boundaries with lifecycle state, version history, and real-time device matching built in.
Key Features#
- Multiple geofence types: evacuation, shelter-in-place, search area, restricted, alert zone, critical zone, surveillance, hazard, and custom
- Geofence lifecycle management: active, pending, expired, cancelled, and draft states
- GeoJSON polygon and multipolygon support with spatial indexing for fast queries
- Auto-expansion over time with configurable rate and maximum limits for modelling spreading hazards such as flood inundation or chemical plumes
- Device location recording with automatic entry, exit, and dwell detection and notification triggers
- KML import and export for bulk boundary management and sharing with external agencies
- Population estimation and address counting within boundaries for resource planning
- Version history tracking for all boundary changes
- Buffer zone generation from existing geofences
- Geofence overlap analysis with percentage calculations
Use Cases#
- Creating and managing evacuation zones during natural disasters with auto-expanding boundaries that track projected hazard spread
- Recording device and personnel locations to detect automatically when responders enter or exit active geofence zones
- Importing search area grids from KML files for search-and-rescue operations using existing GIS toolsets
- Estimating the affected population and address count within a geofence boundary to plan resource deployment and mass notification campaigns
Industry Context#
National emergency management agencies use evacuation geofences during floods, wildfires, and industrial incidents to define affected areas for public warning. Search and rescue coordinators import sector grids into the platform for systematic area coverage tracking. Utility operators define hazard zones around gas leak sites and restrict access automatically when a zone is active. Military and civil defence planners create restricted zones around critical infrastructure and receive alerts when civilian devices enter. Public health authorities use hazard geofences to track movement in and out of quarantine zones during disease outbreaks.
Integration#
The Geofencing domain integrates with Alert Campaign for notification targeting, Incident for emergency response, Location for POLE profiles, DOC Location for duty-of-care tracking, and Map for visualisation. Spatial queries run against PostgreSQL with PostGIS indexing.
Open Standards#
- GeoJSON (RFC 7946): All geofence boundaries are stored, validated, queried, and exported as GeoJSON Polygon and MultiPolygon geometries, with conversion from KML on import.
- OGC KML 2.2: Boundary data is imported from and exported to KML using the OGC namespace
http://www.opengis.net/kml/2.2, enabling interoperability with GIS tools and external agency datasets. - OGC Simple Features Access (ISO 19125): Spatial operations including containment testing, intersection, overlap percentage, buffer generation, and area calculation are performed using the PostGIS implementation of OGC Simple Features SQL (ST_Contains, ST_Intersects, ST_Buffer, ST_GeomFromGeoJSON, ST_Area).
- WGS 84 (EPSG:4326): All coordinates are expressed in the World Geodetic System 1984 reference frame; point geometry is explicitly assigned SRID 4326 in spatial queries.
- SAME (Specific Area Message Encoding): Geofences carry SAME geocodes to support IPAWS integration, allowing boundaries to be correlated with EAS broadcast areas for public alerting.
- ISO 8601: All timestamps for geofence lifecycle events, version history, and device location records are serialised in ISO 8601 format to ensure interoperability with external systems.
Last Reviewed: 2026-02-23 Last Updated: 2026-04-14