How could I add this?

[School]

I notice that the tram in Hong Kong (a city in China) has double tram in service. http://www.hktramways.com/en/home.html
Take a look. I don't know if there is a way to import this.

[Loewe13]

you could take the double öevel bus and make it drive on the tram tracks (not a big conversion because the pixels are the same, just the tracktype must be changed

[natethegreat]

I notice that the tram in Hong Kong (a city in China) has double tram in service. http://www.hktramways.com/en/home.html
Take a look. I don't know if there is a way to import this.

I did something like this already. Look under the topic RailBus & RailTruck.

[metalangel]

The Coronation is already a double-deck tram, but I guess the HK one would be nice to have at the start of the game (something else CS missed - trams and streetcars in 1900 were not the tiny pieces of crap we're given in Locomotion)