Tracks Perpendicular to NEC

So what are the intriguingly complex array of freight trackage that runs beneath the NEC after SJ? In addition, who uses the two tracks that pass under the NEC right outside of the Hudson tubes? I spotted a dark blue locomotive, painted for Susquehanna, and at other times I saw regular freight and couple of CSX (?) engines down there as well.

In one observation, in the blizzard of 2003, in February, these two tracks were covered well above the trackbed in the afternoon, which might have meant there was no traffic there that day.

Any other helpful input is appreciated.

When you say after, do you mean East? If so, you are looking at the remnants of Croxton yard. Its owned by either CR or NS, and used primarily as an intermodal terminal; with the exception of the Flexi-Flo portion. At one time, it was EL's class yard.

And if you're continuing East, you'll cross over the NYS&W and CR's Northern branch. The trackage on CR was once referred to as the bathtub. Should be obvious why.

West of SJ, the trackage that you go over is actually the former Boonton Line right by DB

Outside the tubes is the NYS&W and CSX parallel