but what's the point of having to wait to cross, then having to wait to go again 
waste of gas and time that i would not be too happy about in reality, but interesting function in-game though
As far as I can remember, the setup is actually quicker for going straight or turn right (when right hand driving) because you eleminate a complete signal phase at the main intersection.
My guess is, that the left hand turners actually do not loose mutch of their time (if any), because the 2 signals for them have only two signal phases which can be managed pretty efficiently.
From an engineers point of view and looking at the simulation results, this intersections is more efficient than a normal setup. It's not very common in most parts of the world because of increased consumption of space, higher cost of construction and possible confusion of drivers unfamiliar with this type of intersections (what might actually be a very good point).
