The article in the Daily News by Jerry Gottesman and Steven Spinola raises some issues worthy of discussion. The article in question can be found at:
http://www.nydailynews.com/opinion/extend-7-train-secaucus-article-1.1504464
It has been stated by some that there would be a funding conflict between any further extension of #7 with all that is already on the plate of MTA. From a funding angle this is not necessarily so. In all likelihood any extension of #7 to Secaucus will not involve any funding from MTA. The funding will come from somewhere else just like the funding for the current #7 extension. It was not from the MTA budget but from the city budget. MTA had basically said it can't be done until Bloomberg gave them a pile of cash and said - go do it, if you want to keep that money. So in principle there is little conflict as far as source of money goes between SAS and ESA etc. and whatever happens at the Hudson end of #7. In all likelihood funding for such a venture would involve the PANYNJ since it is their bailiwick - indeed one of their missions - to provide trans-Hudson transportation links.
But that discussion involving only #7 extension belongs in a different thread.
However, the primary thing that is proposed in that article actually places it squarely within the scope of this thread. The thing proposed is a combined tunnel with four segments, two of which are used for Amtrak/NJT and two for #7, similar to how the 63rd Street tunnel is set up. However there are technical issues with that. EPA and Army Corp of Engineers have summarily rejected the tunneling method that was used for the 63rd St. tunnel for use in case of Hudson because of the amount of buried environmentally hazardous stuff that sits in the river bed that no one wants to stir up. So using the cut, drop tunnel segments and cover method is out.
Given that it has to be a bored tunnel, the difficulty of boring a huge diameter tunnel large enough to encompass four tracks in 2x2 configuration presents its own challenges and cost elements which probably surpasses what it would cost to just bore four separate tunnels. The one with civil engineering in their professional expertise list here, is PRR60. maybe he can give us his perspective on this.
Anyway the implicit danger in what is proposed is that it will inevitably lead to possibly another 6 additional years of studies before anything can happen. At present the #7 proposal pretty much reuses the ARC EIS in toto for most of the Hudson tunnel alignment. The Gateway alignment is relatively well understood though still requires an EIS. And the two can proceed independent of each other on different time lines. This proposal mixes both up and puts a completely new and additional thing that must be studied starting from scratch.
It is almost like if I was trying to delay everything by many years while appearing to be well intentioned, I'd do something like this.