The current values for route_type seem a little vague and confusing:

a) What's the difference between a tram and a cable car? b) Would "Subway" be better renamed as "Metro" (urban rail, as opposed to intercity/long haul rail)? c) Would "Cable car" be better renamed as "Street cable car"? d) Would "Gondola" be better renamed as "Arial cable car"? (could become confused with small water taxis - think Venice) e) I guess anyone describing their route as "Funicular" would be familiar with the term, but to save the rest of us launching Wikipedia, why not call it "inclined rail"?

0 - Tram 1 - Subway 2 - Rail 3 - Bus 4 - Ferry 5 - Cable car 6 - Gondola 7 - Funicular