OK. This has been discussed before. From Jamaica there is a little used branch to Long Island City (near the IRT Vernon-Jackson station) that runs through Richmond Hill, Glendale, Middle Village, and Maspeth. Though there is freight traffic, and the LIC station is used for storage of the disel fleet, this line is mostly unused. It's called the "Lower Montauk" branch, presumably becasue it's a place where diesel trains from Montauk could go west of Jamaica (though to my knowledge they don't curently.)
So it has been suggested that this could make a good subway line. Though it would take some work, it would have to be relatively cheap to convert considering how many miles of new subway would be added. The tracks are already in place!
Some things to consider:
1. It has to be electrified.
2. There has to be some kind of connection at the Long Is. City end of the line. If it's to be a new extension of an existing line, it wouldn't be quick to build (consider the one mile long 63rd St. Extension and how long that took!) And it would probably have to bypass the LIC station (since it is presumably needed as an LIRR yard.)
The nearest existing line is the 7. It would be perfect if this could be the route of, say, a number 8 IRT to cut off from the 7. But unfortunately the Steinway tunnel is already overcrowded.
E and F riders might be pretty upset if they lost even part of their connection to the Queens Blvd line--BUT I think the 63rd St. line could easily carry the F, and thus free up some space on 53rd St for a new line-maybe the "P".
Perhaps it could be a new life for the Queens end of the G--but then it would presumably lose its connection to the Queens Blvd. line as the Court Square station is out of the way. You could establish a transfer to the 7.
Or of course there's probably room on the 60th St. tunnel, since it only carries the N ("Never") and R ("Rarely"). But by then we're talking about a noticeably longer connection than from Steinway, Brooklyn, or 53rd St.
In the meantime it could function as a stand-alone line (at least it could have a free tranfer to the 7 as well as the M and J further down). It's better than nothing.
3. Grade crossings would have to be eliminated. They're only acceptable as it is because the line has next-to-no usage.
4. Freight traffic. I have no idea what to do about that. I suppose it could travel via the LIRR main line durring off hours.
5. Stations would have to be built--with transfers to the 7, M, and J/Z.
6. The NIMBY's. I tend to think they wouldn't mind too badly though, since subway trains just aren't as noisy as the LIRR diesels. And because the service would actually bennefit their neighborhoods.
Any thoughts?