[pgrouting-users] Splitting a network to create intersections

[Stephen Woodbridge]

On 5/6/2013 8:16 PM, Greg Allensworth wrote:
> A few weeks ago, Steve Mather posted, and one of his questions was about
> splitting up a trail network so as to create intersections, but without
> splitting unnecessarily.
>
> http://pgrouting-users.974093.n3.nabble.com/pgrouting-users-A-vs-Dijkstra-and-the-nature-of-the-A-implementation-td4025099.html
>
>
> The reply was basically "it's not that hard" which is good to hear,
> though I'm still trying to wrap my head around how exactly I would do
> this. Any explanation of the logic would be helpful there.
>
>
> This fellow at StackExchange posted some code, but but he says that it
> has problems that again I don't quite follow.
>
> http://gis.stackexchange.com/questions/34687/how-to-split-osm-roads-into-individual-segments-at-intersections
>
>
> Any comments on his approach, and what would be going wrong with it also
> creating the unsplit original segments?
>
>
Greg,

I think you want to look at this thread:

http://postgis.17.x6.nabble.com/Break-lines-at-intersections-td4663814.html

If you using postgis 1.5 then note 2nd & 3rd posts from the bottom.

select st_astext(st_dump(st_union(the_geom)).geom) from lines;

-Steve