In typical GI systems, reachability tests are usually carried out via Point-In-Polygon tests. Several problems occur due to these tests:

  1. We need to generate the polygons first
    • Depending on the complexity of the polygon, especially for transit polygons and high travel times, this can be a time consuming task
  2. We need to transfer the generated polygon over the wire (unzipped polygons for large travel times can be >2MB in size) and we have to render them
  3. The Point-In-Polygon test (PIP) needs to be performed
    • This is actually a complex task and can take a lot of time in case of a large number of targets and huge polygons
  4. Point-In-Polygon tests won’t give you precise travel times for your targets
  5. Our polygons render at different levels of precision for performance and readability, depending on the zoom level.

“To sum this up: Our polygons are great for visualizing travel times. For analyzing them, use our Time service.”


  • Get precise travel time to all of your source points
  • Measure for multiple sources
  • Configure travel options to finetune the results

The most powerful part of the Reachability service is that we can get actual measures - not classified distance groups. So we know exactly how far away each point is. In the demo below, we use that precision to determine symbology by applying a d3 color scale to the points, to really visualize precise distance. You can use this for filtering by distance as well..

How to use the reachability service to fetch precise travel times to multiple target locations.