postgis - How to split OSM roads into individual segments at intersections?

I want to create a road-network for use with pgRouting using OpenStreetMap data. I loaded a shapefile from GeoFabrik into a Postgres table (with PostGIS enabled). However, one problem I had was that the roads do not always end at intersections, so I decided to split them all at every intersection or crossing.

To identify all the interesections where roads crossed or intersected I used the following SQL (similar to a previous question):

CREATE TABLE split_points as
SELECT DISTINCT    
   ST_GeometryN(ST_Intersection(a.geom, b.geom),1) as geom      
FROM
   roads as a,
   roads as b
WHERE
    ST_Touches(a.geom, b.geom)
OR

    ST_Crosses(a.geom, b.geom)    
    AND a.gid != b.gid
GROUP BY
   ST_Intersection(a.geom, b.geom);

I now want to split the roads using these points. I used the following approach:

CREATE TABLE split_roads as
SELECT     
    ST_GeomFromEWKB((ST_Dump(ST_Split(g.geom, blade.geom))).geom) As geom,
    generate_series(1,ST_NumGeometries((ST_Split(g.geom, blade.geom)))) as gid

FROM    
    split_points as blade,
    roads as g
WHERE
    ST_Intersects(g.geom, blade.geom);

The problem with this split approach is that the full road length remains in addition to all of the split pieces. To remove these un-split road geometries that were included I used the ST_Equals() function to identify them, and to delete them:

DELETE FROM split_roads USING roads
WHERE ST_Equals(split_roads.geom, roads.geom)

However, this approach does not remove all of the original unsplit geometries (although it does remove some of them). Is there a better approach for deletion (or overall) so that I have only the split geometries in a table?

Answer

Not a real solution to your problem, but try osm2po ... it creates perfect SQL code for routing in pgrouting: http://osm2po.de/