[OSGeo Africa] Travel Time Calculation

[Gavin Fleming]

Hi Uazu

I would use pgRouting (http://pgrouting.org/)

- install pgRouting
- add pgRouting to a PostGIS database
- load your roads and points into the database
- set up network topology by adding nodes with the assign_vertex_id() 
function. Check that you have a properly connected network.
- you can use any value as cost. In this case you'd want to calculate 
the cost field (pgRouting uses 'length' be default) as travel time. You 
could use road length with other information like speed limits to 
calculate or estimate travel time per road segment.
- Set up lists or tables of your villages and urban centres
- Use PostGIS functions to calculate the closest urban centre to each 
village (as the crow flies). It is possible to calculate the closest 
along the network but that is a bit more complicated and straight line 
distance might be good enough.
- Then use pgRouting to calculate the shortest path between each of your 
chosen pairs and return travel time.

To automate this I would write a Python script.

There is good documentation and workshops on the pgRouting site and 
elsewhere.

hth

Gavin

On 14/01/2013 16:20, Uazukuani wrote:
> Dear All
>
>
> I have a problem that I hope someone on this mailing list could assist 
> with.
>
> I want to calculate travel time from (each) VILLAGE to the nearest 
> URBAN CENTER along the road network*.*
>
> The output format could be text or GIS with at least 3 columns: 1. 
> Village, 2. Nearest Urban Centre and 3. Travel Time.
>
>
> I have 3 data sets: 1. Villages (Point), 2. Urban centers (Point) & 3. 
> Roads (Polyline/line) for the whole country (Namibia).
>
>
> I would appreciate if someone refers me to tutorials on this.
>
> I have access to PostGIS, QGIS and GvSIG, ArcInfo, GeoMedia Pro 6.x, 
> MS SQL Server 2008 (Spatial) but am willing to try something else.
>
>
> Rgds,
>
> Uazu
>
>
>
>
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> Africa at lists.osgeo.org
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-- 
regards

Gavin

Gavin Fleming
http://afrispatial.co.za
t: 0218620670
c: 0845965680
f: 0866164820