[OSGeo Africa] Travel Time Calculation

Rainer M Krug r.m.krug at gmail.com
Tue Jan 15 01:04:04 PST 2013

Hash: SHA1

On 15/01/13 08:24, Paul Scott wrote:
> On 15/01/2013 08:53, S Coetzer wrote:
>> Hi
>> If I can suggest a quick an easy way to get estimated time travel.
>> Get your x,y coordinates from point A to point B and plot it on Google maps. Use the GET 
>> DIRECTIONS facility, this would give you an estimated travel time and distance along with 
>> several possible alternative routes.
> For a group of GI professionals, I am bitterly disappointed in these types of answers. Has 
> anyone heard of Djikstra's algorithm (http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm) or 
> a* or Shooting-Star distance algorithms? 
> (http://www.policyalmanac.org/games/aStarTutorial.htm)
> From that, we can infer that distance * average speed = time right?
> Come on ladies and gents! Let us foster an environment for new thinking and innovation, not a 
> forum for consumption of predefined OTS products.
> OSGeo = Open Source = hack and pick and modify = change = new = better = share.

Well - if there are "out of the box" solutions, why not mention them so that they can be used?
Easier in many regards (although not that satisfying and challenging...)

But here are two ideas:

1) You could use R. I wouldn't wonder if there is a package for that.

2) Use GRASS:
a) Rasterize your road network (NULL values for "not on road")
b) use r.cost or r.walk to calculate the least cost paths along the road network (see
http://casoilresource.lawr.ucdavis.edu/drupal/book/export/html/96 "Simple Comparision of Two
Least-Cost Path Approaches" for a comparison of the two)

Warning: I haven't used this approach yet, these are just ideas, but they could work. To get motre
info, I would suggest to google and ask on the GRASS user mailing list.



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Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology, UCT), Dipl. Phys.

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

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