What part of "street" do you not understand? Streets are where streetcars run.

I've only been in that part of Portland once, and the traffic (midday weekend) didn't seem too bad. Of course, we were only trying to get to/from OMSI from the freeway (were staying out of town with relatives) so it was a very limited exposure. Could easily see, though, where things might get crowded; streets aren't all that big to handle cars, trucks, AND streetcars.

Is this the project that will build a new rail/ped-only bridge?