According to the Ontario drivers hand book:
U-turn
Before you make a U-turn, check to make sure there is no sign saying not to.
To make a U-turn safely, you must be able to see well in both directions. It is illegal to make a U-turn on a curve in the road, on or near a railway crossing or hilltop, or near a bridge or tunnel that blocks your view. Never make a U-turn unless you can see at least 150 metres in both directions.
To make a U-turn, signal for a right turn, check your mirror and over your shoulder and pull over to the right side of the road. Stop. Signal a left turn and when traffic is clear in both directions, move forward and turn quickly and sharply into the opposite lane. Check for traffic as you turn.
I can't recall seeing any signs for no U turn. The tracks - -Street cars, which move really slow. It was an advanced green so little chance of being hit by the street cars or traffic in the opposite direction. Even driving a regular car, I rarely do a U turn as to me its a such a grey area. This is the first time I looked up the clause in the handbook, but even now, I would be reluctant to do one.