An introduction to using pgRouting with Ordnance Survey Open Data in QGIS with the pgRouting Layer plugin. Presentation given at the 3rd QGIS UK user group meeting in Edinburgh on 5th May 2015.

1. PGROUTING IN QGIS
How to tame your network - Ross McDonald @mixedbredie

2. Here be dragons
Get
Merge
Load
Update
Populate
Build
Analyse
Get lost
http://ghost.mixedbredie.net/pgrouting-with-strategi/

3. Get the data
Open Data Download
http://bit.ly/1I0Fwz3

4. Merge the roads
There’s a QGIS tool for
that!
Select: Motorways, A
roads, B roads, primary
routes, minor roads and
local streets
Vector > Data
Management Tools >
Merge Shapefiles to
One…

5. Load into PostGIS
QGIS DB
Manager
Schema
Table
Primary key
Geometry
SRID
Spatial index

6. Update the network table
Add the required columns for pgRouting
Build the indices to make it fast
ALTER TABLE os_strategi.strat_rds
ADD COLUMN source integer,
ADD COLUMN target integer, etc., etc.
CREATE INDEX strat_rds_source_idx ON
os_strategi.strat_rds USING btree(source);

7. Populate the network table
Start and end coordinates
Length costs
Speed (average driving / walking speeds)
Time = length / speed
Reverse costs

8. Build the network topology
Creates a node table used for start and end
points
SELECT pgr_createtopology(
'os_strategi.strat_rds', 0.001, 'geometry',
'gid', 'source', 'target');

9. Analyse the network
Checks for errors
MULTILINESTRING v LINESTRING
SELECT pgr_analyzegraph(
'os_strategi.strat_rds', 0.001, 'geometry',
'gid', 'source', 'target');

10. Get Lost
© Crown copyright and database right 2015 100023404

11. Djikstra Shortest Path
© Crown copyright and database right 2015 100023404
Strategi Network

12. Driving Distance (10min)
© Crown copyright and database right 2015 100023404
Strategi Network

13. Alpha Shapes (isochrones)
© Crown copyright and database right 2015 100023404
Strategi Network

14. Astar heuristic shortest path
Meridian2 Network
© Crown copyright and database right 2015 100023404

15. Turn Restricted Shortest Path
Integrated Transport Network with RRI
© Crown copyright and database right 2015 100023404

16. Geoserver WMS + TRSP
http://ghost.mixedbredie.net/combining-pgrouting-functions-in-openlayers3/

17. ITN+RRI=TRSP
'select to_cost, teid as
target_id,
feid||coalesce('',''||via,'''') as
via_path from
itn_turn_restrictions‘
Directed = true
Has reverse = true

18. Guides
http://anitagraser.com/?s=pgrouting
http://ghost.mixedbredie.net/pgrouting-with-
strategi/
http://ghost.mixedbredie.net/using-
pgrouting-with-os-meridian2/
http://ghost.mixedbredie.net/building-itn-for-
pgrouting/