They posted the feasibility study of the four options they failed under the existing Penn Station, but require additional studies on extended properties to meet the 48 trains per hour goal.
https://pennstationcomplex.info/wp-c...Considered.pdf
Briefly, as I understand the problems:
They couldn't find a way to build cheaply under the existing station, and they couldn't solve the problem with through running. The two huge obstacles for through running is the requirement of 30 feet wide platforms for both loading and unloading passengers at a platform at the same time which reduced the number of tracks and platforms, and having difficulties for turning reverse trains during peak rush hours because reversing the trains requires running through four tunnels vs two tunnels reducing throughput, or turning the trains at the platforms without gaining the time advantage of through trains.
It will be interesting to see what the planners arrive at in the future, and how much more it will cost.
Typical governmental agency boondoggle. Build several tunnels to increase capacity, then have to build a larger train station to put the extra trains in.
A few Billion for new tunnels, a few Billion for a new train hall, and another few Billion for an expanded station capacity. Billions and Billions of more money needed to reach the never ending final project.