public transport

[mind]

Hello, All,

I'm preparing a city public transport scheme and would like to make it a bit more understandable for foreigners, too. Does anybody know if there is a standard (more or less) way of distinguishing bus, tram and trolley lines from each other? Maybe, some color codes, or letters, or some graphic symbols?

Thanks!

[Saaropean]

Of course there are icons for that: