Join intersecting lines with PostGIS

I believe the code below is a little cleaner solution than the selected answer for a couple of reasons. First no table joins are necessary and thus an addendum to the 'ON' clause is not needed for each of the street attributes, and second the above methodology can potentially produce multi-linestrings if there are multiple, non-contiguous clusters of streets that have all of the same attribute values, whereas ST_Dump takes care of that issue in this solution.

SELECT (ST_Dump(geom)).geom AS geom, "road_id", "road_type"
FROM (
    SELECT ST_LineMerge(ST_Union(geom)) AS geom, "road_id", "road_type"
    FROM "RoadCentreLines"
    GROUP BY "road_id", "road_type"
) AS street_union

Seems this works

SELECT a."Road_ID",a."Road_Type", ST_LineMerge(ST_Collect(a.the_geom))
FROM "RoadCentreLines" as a 
LEFT JOIN "RoadCentreLines" as b ON 
ST_Touches(a.the_geom,b.the_geom) 
    AND a."Road_Type" = b."Road_Type" 
    AND a."Road_ID" = b."Road_ID"
GROUP BY ST_Touches(a.the_geom,b.the_geom), a."Road_Type", a."Road_ID"