The WorkpassID app uses geofencing to automatically register attendance based on a worker's physical location, without requiring them to manually check in or out. This article explains how geofencing works, what its limits are, and what to keep in mind when setting up geofences for your projects.
What is a geofence?
A geofence is a digital boundary around a geographic area, such as a construction site. When a worker's phone crosses this boundary, the app detects their presence and automatically checks them in or out.
To determine the phone's location, the WorkpassID app uses a combination of:
GPS location data
Nearby Wi-Fi networks
Mobile cell towers
What the geofence does
Check-in: when a worker enters the geofence area, the app automatically checks them in
Check-out: when they leave, the app checks them out
Notification: workers receive a notification confirming each check-in or check-out
Rules for setting up geofences
To make geofencing work reliably, follow these rules when configuring project locations.
Minimum size
A geofence must be at least 200 meters in diameter. Larger is often better. Smaller zones result in unreliable or incorrect detection.
Distance between geofences
Geofences must be at least 200 meters apart. Overlapping geofences are not allowed. They cause false check-ins or missed events.
Updating an existing geofence
When you update a geofence, workers need to open the app for the change to take effect. The actual update only happens when the app is opened.
Workers are prompted to open the app in two situations:
After any geofence update: workers receive a notification asking them to open the app
At check-in: if the project's geofences have changed since they last opened the app, they're also prompted to open the app at that moment
Important to communicate this to workers. If they don't open the app after an update, they'll still be using the old geofence boundaries.
Limitations to keep in mind
Geofencing depends on factors outside the app's control. Even with a correctly configured geofence, the following can cause delays or missed events.
No or poor internet connection
If the worker has no internet, their check-in/check-out is stored locally on the phone and sent later when one of the following happens:
The worker opens the app
The phone is plugged in to charge
Stored events that aren't sent within 24 hours are dropped and won't be sent
The "Currently on site" overview for gatekeepers may be delayed significantly in these cases
Phone battery settings
Some devices restrict background location updates to save battery. For geofencing to work reliably, the worker's phone must have:
Permission to use location at all times (not just while the app is open)
Battery optimization disabled for the WorkpassID app
Android devices are more likely than iPhones to restrict background location in the background.
GPS and environmental interference
GPS signals may be weak in:
Tunnels
Large buildings
Dense urban areas
Sites with tall metal structures (common on construction sites)
This may result in missed or incorrect check-ins or check-outs.
Type of phone
Geofencing behaviour varies across devices and operating systems. Lower-end or older phones tend to have less reliable location detection.
What to tell your workers
For geofencing to work reliably on a worker's phone, they should:
Open the app at least once per day
Allow always-on location access for the WorkpassID app
Turn off battery optimization for the WorkpassID app
Make sure mobile data or Wi-Fi is available when on site
What this means for attendance reports
Each check-in is matched with a check-out, for reliable attendance data
The real-time "Currently on site" view may be delayed if a worker has no internet at the time