NIMBYkiller wrote:Again, simply asking if it's physically possible, not about the NIMBY or political aspect.
NIMBYkiller, the short answer is yes for 5,6 & 7 if you dive and shift northward, but I'm not sure about 0. As it is isolated to the south of tracks 1,2,3 & 4, incorporating track 0 track into part of a pathway for theoretical NJ Transit service via tunnel under the Delaware isn't really practical.
A previously missing discussion point is what happens when you get to Camden. There is no room adjacent to PATCO & The Riverline to build a portal to make a connection onto the embankments heading south or east, plus the grade change is significant. To access the Mount Holly Branch, you would need to tunnel east beneath the Cooper River to a portal near the Conrail Pavonia Yard.
For the southern branches, you would need to tunnel south underneath Seventh Street to a portal south of Atlantic Avenue. The rough Google Earth estimate for both tunnel branches, assuming the theoretical tunnel is placed under Arch Street in Philadelphia and would pass by Walter Rand T.C beneath MLK Boulevard in Camden, yields approximately 5.4 miles. Add electrification into the mix, and then (for comparison) consider the projected costs associated with the Gateway project in NYC.