…not a modern one. Sure it’s cute, and it goes under the Viaduct and they extended it to go to the International District (all the way to King Street Station), but it’s not modern, and doesn’t attract the ridership that would be useful because:
a) It doesn’t go far enough. It basically serves the waterfront and that’s it. It would have to go to at least the Seattle Center to actually be useful.
b) It is rickety and slow. It’s more of a tourist attraction than a useful transit scheme.
I think the streetcar’s usefulness is exhibited by how empty it is everytime I ride on it. For contrast, the Elliot Bay Water Taxi has been packed each time I have been on it.
c) It doesn’t serve a corridor that is populated by businesses or inhabited by people. If it actually went through Belltown, it’d be a different story, but as it is now, it’s only useful for going to the waterfront.