Dobermann:
As I said earlier, a "Y Track" consists of two diverging D16 curve tracks. Your trolley may have trouble getting into the "Y."
Former forum member Lee Willis has two books out on the subject of 'Tracks. He covers the original K-Line Superstreets, the K-Line by Lionel Superstreets and the Bachmann E-ZStreets (all essentially the same). I recommend his book "'Streets for O-Gauge Model Railroads." It's on Amazon for $14.95.
In his book, Lee shows that the Atlas Trolley, the Williams Peter Witt Trolley and the MTH PCC will not work on D16 curves. (The MTH PCC will work with modifications to the PCC.)
I would go with the turnouts, OR---make a dogbone within your space, so that the trolley turns on a D21 circle at each end and goes back in the other direction. Then, you do not have to worry about the trolley not fitting into the "Y" and you don't have to worry about making the turnouts non-derailing.
You would wind up with two parallel lanes of Streets, which Lee says in his book, look more realistic than a single lane. You could even do what he calls a "crushed" dogbone where the lanes are next to each other.
John Knapp