Isochrones for transit in New York City in QGIS

kyle.bell · 2019-04-03 20:14:33 UTC

Is there a method for including transit travel time isochrones via the ORS Tools plugin for QGIS (or via any other existing plugins)?

I’m new to the use of APIs and can’t seem to figure out whether ORS or Google Maps will let me do this calculation.

Thanks,

Kyle

nils · 2019-04-03 20:22:32 UTC

Nope, only GraphHopper and Valhalla can do this at the moment! And not in QGIS via plugins, only normal ‘add vector layer from GeoJson protocol’ and a valid query URL from one of those providers. Valhalla is available over Mapbox, though a little hidden: https://api.mapbox.com/valhalla/v1

kyle.bell · 2019-04-03 20:48:14 UTC

Much appreciated! I took a look at Valhalla, since I already have a Mapbox account.

I’ve reached the point of Add Layer > Vector > Protocol > GeoJSON

Is there any documentation on how to set it up?

nils · 2019-04-04 07:06:32 UTC

github.com

valhalla/valhalla/blob/master/docs/api/isochrone/api-reference.md

# Isochrone service API reference

An isochrone is a line that connects points of equal travel time about a given location, from the Greek roots of `iso` for equal and `chrone` for time. Valhalla's isochrone service computes areas that are reachable within specified time intervals from a location, and returns the reachable regions as contours of polygons or lines that you can display on a map.

Isochrone maps share some of the same concepts and terminology with familiar topographic maps, which depict contour lines for points of equal elevation. For this reason other terms common in topography apply, such as contours or isolines.

This is an example of isochrones showing the travel times by driving from a location in Melbourne, as depicted in Mobility Explorer.

![Isochrones for travel times by walking in Lancaster, PA](/images/isochrone.png)

## Inputs of the Isochrone service

An isochrone request run locally takes the form of `localhost:8002/isochrone?json={}`, where the JSON inputs inside the `{}` includes an array of at least one location and options for the [route costing model](/turn-by-turn/api-reference/#costing-models).

For example, you can use the isochrone service to find out where you can travel within a 15-minute walk from your office building. The API request for this uses `isochrone?` as the request action, `pedestrian` costing, and a single contour for a 15-minute time interval. The response is GeoJSON, which you can display on a map to visualize where you might be able to walk.

```
{"locations":[{"lat":40.744014,"lon":-73.990508}],"costing":"pedestrian","contours":[{"time":15,"color":"ff0000"}]}&id=Walk_From_Office
```

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Good luck with that haha one of the worst APIs I’ve ever seen! Genius service, but clearly overengineered API. Mapbox can do POST, QGIS can’t though. Watch out URL encoding.