I don't recall the F train being reinforced with any grenade-deflecting steel alloy in the past few years, and I doubt that any other commtuter trains have been designed to resist anti-tank mines or improvised explosives, let alone an RPG or surface-to-air missile.
I work security at Shea Stadium and Madison Square Garden.
Shea might; and I said might, get a pass, what with the Republican National Convention coming to the Garden. That is the target.
But if we listen to the attack in Spain, they will wait until closer to the election.
On a lighter note, the last episode of "The Sopranos" sucked out loud!
I'm not aware of any MANPADS type system that would a)guide on a train, or b)come under command control in the limited distance between the embankment and the train itself.
Actually, mines/IEDs would be much more damaging- standard US AT mine (M15) carries 20+ lbs of HE, while the AT4's warhead is ~5 pounds HE, and the stinger about the same.
I'd be more worried if we saw evidence that someone had been digging around the roadbed, or stashing a coule of shoe boxes on bridge supports.