Originally Posted by Critic

AirTrain serves as the landside link between the terminals, rental car agencies, parking and mass transit (Amtrak/NJ Transit). Similar to the Airtrain at SFO, if you're familiar with that.

As much as I used to think it was overkill, I'm starting to think PHL did the exit lanes right when they built their D/E connector complex. Coming out of the D gates, if you want to exit to landside, you have to pass through a set of automatic doors, followed by a subway-style automatic faregate (DC Metro/ATL MARTA/BART style, not NYC style) into individual lanes (think the Eliminator from the old American Gladiators), then finally through another set of automatic doors. There's no visible TSA presence, but I imagine the airlock is being monitored by CCTV, and TSA could lock down individual lanes or the whole system remotely if they needed to.