Topology created by osm2pgrouting leaves some ways with identical source and target nodes, making them un-routable about osm2pgrouting HOT 5 CLOSED

Currently experimenting with different snapping tolerances on the pgr_createTopology function. Will report back with findings.

from osm2pgrouting.

Ok, ran the following (changing the tolerance in Export2DB.cpp from 0.00001 to 0.0000001):

SELECT pgr_createTopology('ways', 0.0000001, 'the_geom', 'gid');

Followed by:

SELECT pgr_analyzeGraph('ways', 0.0000001,'the_geom','gid','source','target');

Which stated that the topology was "OK"

Now there don't seem to be any ways with the same source and target, as verified by running:

SELECT * FROM ways WHERE source = target

I need to continue testing to see if this causes any other problems with my routes, but so far so good.

from osm2pgrouting.

Thanks for looking at this. The "snapping tolerance" is an attribute of the pgRouting function and if there exist tiny ways as you mention, then this looks like a data issue. If these ways are valid though, then the tolerance needs to be smaller.
But this means that other areas, where mappers are not careful with connecting ways would get disconnected networks.

Probably it would be best to make the snapping tolerance an optional parameter of osm2pgrouting.

from osm2pgrouting.

The ways mentioned were definitely legitimate (tiny bits of road wedged between 2 slightly-offset junctions), however I understand that changing the tolerance has an impact on others who may not have these issues.

Having the tolerance as a user-definable parameter (and mention in the documentation) would be perfect.

from osm2pgrouting.

With the alpha version this no longer happens
Test on Washington dc area:

select gid from ospr.ways where source = target;
 gid 
-----
(0 rows)

from osm2pgrouting.