Using heatmap.js with Google Maps

The Electramedics Real-time Service Area is an interesting Google Map that is using heatmap.js to create a real-time heat map.

I'm not exactly sure what the heat map represents or even what an elctramedic does but the map is a good example of using heatmap.js with Google Maps. The map also has an interesting polygon feature that manages to create a boundary box for the heat map on the fly.

I assume the heat map and bounding box are being used to visualise the current area that the team of electricians are covering in real-time. But then I could be wrong.