In the SitStat Monitor, users can see the relative drivetime measurements of particular units.
Drivetime Logic:
- Individual units must be identified in the unit lookup data with the "showDrivetime" flag = 'true'; by default, this flag is set to 'false'.
- Only "showDrivetime" units with an Intterra status of “Available” or “Station” status have isochrones/drivetime polygons associated with them. All other known, or unknown statuses, will not display a drivetime polygon.
- Drivetime polygons/isochrones promptly go away when a unit status changes.
- Use the selections within the drivetime menu to further refine by the provided filters. Filters are configurable!
- Drivetime parameters (# of minutes) and colors are configurable.
- If using Density: Five overlapping isochrones/drivetime polygons will show a completely opaque area.
How Drivetime Works:
Our new SitStat tool will provide drivetime polygons out of the box! These polygons provide an estimate of how far a vehicle can travel from a location in four and seven minutes.
Please keep in mind that there are some inaccuracies associated with computing drive time from OSM data. The algorithm itself has inherent inaccuracy. We update our copy of the OSM vector street data set annually, so recent changes to roads may not be captured. Real-time conditions including construction, accidents, weather conditions, and traffic patterns are not factored into these shapes either. Also, the polygons are also somewhat rounded and smoothed out from their computed "spider-web" shape to provide a more meaningful interpretation of coverage.
All these caveats aside, the drivetime shapes represent a useful approximation of coverage for a department, especially for identifying coverage gaps.