Whether you do it after the light goes red (illegal) or immediately on green (also illegal), it's the same underlying problem: the intersection needs a protected left turn in the signal sequence.
Then the laws in Pittsburgh are just bad. Not a design question at all.
Here you oull into the intersection on green, turn slightly ti a big white cross on the road for exactly this purpose and go when it is clear. This happens when the oncoming side has red, but before the crossing cars have green. The time between red and green is long enough for all two or three cars to clear the intersection.
Get better laws i guess?