given sets of vehicle passing on each edge, how to get most used vehicle to avoid transition?

Question

I have two tables: one, the resulting table from converting osm.xml via osm2po so I can use pgRouting, and another one that contains information on what edges each public vehicle passes through (|vehicle_code|edge_ids|). Note: one edge_id might contain many public vehicle codes.

So after executing pgRouting shortest path query, I want to know which vehicles are the best to use to navigate the shortest path to avoid too many transitions.

I'm kinda new to SQL; please help. Thanks!