The Proposed "Blue Route" I-476

[Beltway]

The PA Turnpike east of Bensalem is slated to be I-95 once the 95-Turnpike interchange is completed.  Had I-476 & I-276 been designated as I-495... maybe Penn and NJDOT could assign what's slated to be a westerly extension of I-195 as I-495 as well  ; especially since the original I-495 in North Jersey was downgraded to NJ 495 decades ago.

I-695 would be my choice for the western bypass of Philadelphia. 

DE I-495 is too close for it to be used in PA, IMHO.

The unbuilt PA I-695 Cobbs Creek Expressway could have been an I-e76 as it only had one terminus at I-95.  Such as I-476.

[Roadsguy]

It would have fed into the Crosstown Expressway and ended at 95 again at the Columbus Blvd. ramps.

[Beltway]

It would have fed into the Crosstown Expressway and ended at 95 again at the Columbus Blvd. ramps.

Per the research I've done, the Crosstown Expressway would not have been an Interstate (although one opinion says yes, I tend to doubt it was the case).

[Beltway]

I-695 would be my choice for the western bypass of Philadelphia. 

Perhaps the reason for the I-276 and I-476 being used, was that perhaps the PTC drove that decision by wanting that part of the Turnpike to have the same base route number as the rest of the Turnpike, for their own form of continuity.  Plus they could have posted 276 immediately in the 1960s, while the "Blue Route" would not be built for many years in the future.

That is my best surmise ...