In QGIS 2.16.3, I have a series of bus routes (with different attributes), all in the same shapefile. For simplicity, they all run every 30 minutes. They often share sections of route - for example, bus #1 and #2 use the same road out of the city centre. On this section, therefore, buses run every 15 minutes.
I want to select these roads where two or more buses run (i.e. where lines in the same shapefile intersect). Along roads with two or more buses, the lines overlap perfectly.
The best I've got so far is to reduce transparency, so that roads with more than one bus appear darker than those without - but it isn't what I'm looking for.