In Maryland they are rectangular instead of round....but it was round in Illinois though... and nice streetlight shadow!

The loops here are rectangular too, there are some similar diamond shaped ones used to detect congestion on the freeways too.

Round (or square) loops are usually for presence detection only. It detects when a vehicle is over it...or passing over it as it drives by. Rectangular loops do that as well, but also have the option for V+O (Vehicle and Occupancy) control to adjust the coordination plans for nearby intersections when several cars are waiting in a queue

This is where video detection is your friend...since you can design whatever size "loop" you want since its all virtual!

Well one of my friends has reported that he went through 3 cycles waiting for a left turn and it never did a left turn!

Sounds like a broken loop wire...still should go into failsafe mode