PC: Rail Road Routes

["jfulham" <jfulham@xxxxxxxxxxxxx>]

OK, PC fans, here is a question for you all....
I take the AMTRAK between Providence and NYC (I live in Cape Cod) and
something has intrigued me.
The New Haven owned the route between Boston and NYC but, as I recall, they
went in to Grand Central. AMTRAK goes in to Penn Station which was the old
PRR. I think that AMTRAK seems to connect off of the New Haven to the Penn
Station line just south of New Rochelle -- am I right? Also, the route the
train follows from there -- the Bronx, across in to Brooklyn, and through
the Sunnyside Yards -- who built that connection? Who built that huge bridge
next to the Triboro Bridge? I'd love to hear from you truly dedicated types
who also know the NYC and PRR.
Thanks,
Jay Fulham