Why aren't NEC based commuter railroads using ALP-45DP's? - Trains Magazine

MidlandMike

 NJT does not have the option of 3rd rail in the Hudson Tunnels.

Well, yes they do; there's just little point in adding the DC equipment and shoes just to allow diesels to transit the tunnel.  (They could use something like a P32DC from Empire service for that, as the things are 'hangared' right there at NYP, so if there were an advantage to it, I suspect that would have been tried.)

Much more sensible (and, arguably, economical with respect to operating cost) is to make the diesel operable as a full AC electric when under catenary, where it can develop very high horsepower under conditions third-rail locomotives could only dream about.  In part this pre-assumes a well-developed AC overhead-wire infrastructure... which exists for both NJT and SEPTA in a number of contexts. 

Note also that there is a somewhat restricted number of services that involve trips over trackage that is not fully wired, and not economical at this time to wire fully, but that require high speed and no engine change.  One example of this was the Atlantic City Express operated with an electric at one end and a diesel at the other; this would have been a perfect service for an ALP-45DP... but would it generate sufficient revenue to justify the capital expense?

Big place I'd expect this sort of power to be used by NJT would be service up to the 'fourth airport' at Stewart, with quick service to 'the other airports' via operation through the tunnels or over the portion of the NEC going to Liberty whatever-it's-called (I still just call it Newark Airport).  Again, the politics of making this trick workable will likely outweigh the high first cost of the locomotives... at least, I certainly hope so.  On the other hand, what you do with service to Stewart from a new line laid across at Tappan Zee is far less certain -- time to break out the tripower blueprints?