Indeed, strange how that's not mentioned at all. Or whether any transportation engineers have evaluated what kind of traffic reduction would occur from using all these tunnels for a subway system instead of just moving a few cars around.

Edit: The more I think about it, the worse it seems. Compare how much space is eaten out of the road above for a few cars... per minute?...to go up/down to this tunnel vs. how many a stairwell could take up/down to the subway. Even if the car's were relatively crammed close together in the tunnel, I can't imagine it would be anywhere near the density you could fit on subway trains. The economics of this make no sense.... unless you consider that this will be something that only the incredibly elite will be able to afford. The majority of people in rush hour LA traffic will remain stuck there, the rich will go down I guess.