It's just a little 7" radius loop, but boy it was tough to install.
It's made of 3 pieces of Atlas flex-track. The 3/4 loop - and it is a perfect circular arc not the semi-ellipse of that slightly distorted photo - is cut from one piece, the long exit straight is the second, and that entry transition is the third.
The transition piece had a little special preparation before installation. First, Atlas flex has more-or-less all the ties interconnected on one side, and every other tie connected on the other. To make the piece more flexible I removed every other interconnection from the first side, so that it was as flexible as the other. Then the track was carefully wrapped edge-wise around the perimeter of that old tobacco can (I use it for stashing old screws and nuts, so it's heavy). This gives the track a slight built-in curvature. After curving, the track was trimmed a bit so that the rail ends that join the loop have been curved by the can - this helps get a little better joint between the transition and the loop.
That's all the track installed on the new streetcar layout. I hear a soldering iron - and summer vacation - calling my name :-)