Reach factor meaning and calculation

Aaron-JE · May 13, 2020, 9:02am

Morning!
What does reachfactor mean and how is it calculated?
Thanks!

amandus · May 13, 2020, 9:40am

Aaron-JE · May 18, 2020, 11:39am

Perfect! And any information on how it is calculated?

amandus · May 18, 2020, 2:42pm

Basically it’s the isochrones proportion of a circle generated with a mean speed for the specific profile.

Mean values per profile are:

profile	mean speed (km/h)
cycling-regular	15
cycling-mountain	14
cycling-electric	20
cycling-road	25
driving-car	100
driving-hgv	70
foot-walking	5
foot-hiking	5
wheelchair	4

If you have a 10 min isochrone for car you would have a radius of 360 * 600 m for the circle the isochrone is compared to.
It’s area would therefore be: (216000)^2 * pi
Then divide the actual 10 min isochrone area by this value and you have your reachfactor.

For further infos check the code:

github.com

GIScience/openrouteservice/blob/master/openrouteservice/src/main/java/org/heigit/ors/isochrones/builders/concaveballs/ConcaveBallsIsochroneMapBuilder.java

/*  This file is part of Openrouteservice.
 *
 *  Openrouteservice is free software; you can redistribute it and/or modify it under the terms of the 
 *  GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 
 *  of the License, or (at your option) any later version.

 *  This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 
 *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
 *  See the GNU Lesser General Public License for more details.

 *  You should have received a copy of the GNU Lesser General Public License along with this library; 
 *  if not, see <https://www.gnu.org/licenses/>.  
 */
package org.heigit.ors.isochrones.builders.concaveballs;

import com.carrotsearch.hppc.IntObjectMap;
import com.carrotsearch.hppc.cursors.IntObjectCursor;
import com.graphhopper.coll.GHIntObjectHashMap;
import com.graphhopper.routing.util.*;
import com.graphhopper.storage.GraphHopperStorage;

This file has been truncated. show original

github.com

GIScience/openrouteservice/blob/master/openrouteservice/src/main/java/org/heigit/ors/isochrones/Isochrone.java#L93-L97


public double calcReachfactor(String units) {

    double r = getMeanRadius(units);

    double maxArea = Math.PI * r * r;

    hasReachfactor = true;

    return FormatUtility.roundToDecimals(area / maxArea, 4);

Best regards