osrm-isochrone

osrm-isochrone

Warning: this is experimental

Generate drive-time isochrones from OpenStreetMap data using OSRM.

Install

npm install osrm-isochrone

Build

An osrm file is required for routing. This can be generated using included binaries. (Note: this will take a lot of processing power if you are planning to use the entire planet.osm file, for general use a regional OSM data extract is preferable. More info here)

#first download an osm file containing the area you need 
./node_modules/osrm-isochrone/osrm/lib/binding/osrm-extract mydata.osm -p ./node_modules/osrm-isochrone/osrm/test/data/car.lua
./node_modules/osrm-isochrone/osrm/lib/binding/osrm-prepare mydata.osrm -p ./node_modules/osrm-isochrone/osrm/test/data/car.lua

Usage

Create a file containing something such as:

var isochrone = require('osrm-isochrone');
 
var time = 300; // 300 second drivetime (5 minutes)
var location = [-77.02926635742188,38.90011780426885]; // center point
    // Note: coordinates are E/W , N/S
var options = {
  resolution: 25, // sample resolution
  maxspeed: 70, // in 'unit'/hour
  unit: 'miles', // 'miles' or 'kilometers'
  network: './dc.osrm' // prebuilt dc osrm network file, or use the one just built.
}
 
isochrone(location, time, options, function(err, drivetime) {
  if(err) throw err;
  // a geojson linestring
  console.log(JSON.stringify(drivetime))
});

Run with

node my-file.js

The output will be in GeoJSON format.

Advanced

Alternatively the network parameter can be an OSRM module instance. Allowing setup an OSRM with custom parameters, e.g. usage of shared-memory.

You can too define your own function to draw line/polygon instead of default:

var concave = require('turf-concave');
var Isochrone = require('osrm-isochrone');
 
var time = 300; // 300 second drivetime (5 minutes)
var location = [-77.02926635742188,38.90011780426885]; // center point
var options = {
  resolution: 25, // sample resolution
  maxspeed: 70, // in 'unit'/hour
  unit: 'miles', // 'miles' or 'kilometers'
  network: './dc.osrm' // prebuild dc osrm network file
}
 
var isochrone = new Isochrone(location, time, options, function(err, drivetime) {
  if(err) throw err;
  // your geojson from draw overload
  console.log(JSON.stringify(drivetime))
});
isochrone.draw = function(destinations) {
  var inside = destinations.features.filter(function(feat) {
    return feat.properties.eta <= time;
  });
  destinations.features = inside;
  return concave(destinations, this.sizeCellGrid, unit);
}
isochrone.getIsochrone();