Geofence

A geofence is a defined area — a circle around a point, a drawn polygon, or a corridor along a route — that the tracking platform tests every position report against. Crossing the boundary generates an entry or exit event; staying inside generates dwell.

The useful implementations treat the fence as a workflow trigger rather than a notification. Entry at a consignee can start the detention clock, notify the customer and open the unloading task. Exit can close the trip leg and release the vehicle for its next allocation. A fence that only sends an alert to a supervisor's phone is doing a fraction of the available work.

The design detail that determines whether it works is fence size. Too tight and GPS drift causes repeated false entry and exit pairs; too loose and the vehicle registers as arrived while still on the approach road. Sites with poor sky visibility — covered yards, urban canyons — need larger fences and a minimum dwell before the event is treated as real.