I think people are a bit confused about the whole Penn South story. There are several parts (not necessarily in chronological order) to the Penn South plan.
Part 1. Penn South Upper level station with six tracks terminating just around 7th Ave. together with connections to the Gateway Tunnels and the original North River Tubes. The connection toe the Gateway Tunnel through the tunnel boxes that have been discussed in this forum elsewhere, at length I might add, actually connect through a bellmouth, one for each tunnel. More on the reason in Part 2. These bell mouths will be near the river bank for later additional construction.
Part 2. Penn South Lower level station, a four track deep station built using TBMs deep below Penn South Upper, this one with four tracks, connecting to the Gateway Tunnels via the bellmouths mentioned in Part 1, and no connections to the original North River Tunnels, together with deep bored tunnel exiting to the east. The exact routing to be determined by NEC Futures plans.
Part 3. Possible eastward tunnel from Penn South Upper to Queens under the East River. This has also been mentioned as something that will be decided later, but the vertical placement of the tracks in Penn South Upper is carefully designed so that such an eastward breakout will not interfere with the 7th Ave and 6th Ave Subway Lines and 6th Ave PATH Station.
There are no water tunnel issues with the breakout from Penn South Upper. It is relatively shallow tunnel at 6th Ave and follows the same contour as the 33rd and 32nd Street eastward exit tunnels from Penn Station. It is just that they would be under 31st St. The water tunnel issue was with an eastward breakout from the ARC terminus station which was designed to be much deeper than the proposed Penn South Upper station. There may be an issue with it with respect to the Penn South Lower station, but the details of it are fuzzy enough to know for sure. In any case that is way out in the future as far as anyone can tell.
It looks like at least the 6 terminating track South extension to Penn Station, making it a 27 platform track station will become reality. The rest of it is stuff that is being designed in, but whether it will be built or not is a separate issue. Penn Station South will be almost exclusively used by NJ Transit according to early operating plans that have been mentioned, and they will not have any direct access from Moynihan concourse. There may be a long tunnel built along the edge of 31st St to connect the M Concourse to the Mezzanine concourse to access those platforms, or it may just be something tacked onto the proposed passageway from the M Concourse to the platforms for tracks 1-4.
Edited by jis, Yesterday, 05:48 PM.