[OSRM-talk] 'penalty' for snapping

Steven M. Ottens steven at minst.net
Tue Apr 19 19:39:28 UTC 2016


Hi all,

I am working on a tool that will calculate the travel time from villages 
to for instance the nearest hospital for rural accessibility analysis. 
So far I have build a tool which will calculate this for 215.000 
villages in a few minutes, thanks to the help of Daniel P. However I 
realized that not all villages are on a road, actually quite a few are 
at least an hour walk from the nearest drivable road see: 
http://stvno.github.io/img/OSRM-snapping.png
The villages are typically connected to the roads by informal trails, 
which I do not have as a road network. So I was wondering if it would be 
possible to add a basic penalty to the distance of the point to the 
nearest road.
I am aware that the nearest service will provide me with the distance: 
https://github.com/Project-OSRM/osrm-backend/wiki/New-Server-api#service-nearest 
but before I am going to calculate the extra traveltime for each 
village, I was wondering if it is possible to integrate this with an 
osrm.table request. I am aware this opens quite a can of worms: if there 
is a penalty to snapping, it might be worth it to snap to a road which 
is further away, but in the end quicker to get to the destination. But 
for the moment I'm happy with just the added traveltime for nearest road 
snapping.

Any suggestions on how to handle this?

Steven





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