Commenter Noah asks the following:
Do you know more about this, from Wikipedia?
“SEPTA’s Market-Frankford Line (also known as the “El”) and all of SEPTA’s Subway-Surface Lines stop at the 30th Street subway station, less than 1/2 block (< 1/10 mile) from the southwest entrance to 30th Street Station. A tunnel connecting the underground subway station and 30th Street Station was closed due to crime and vagrancy concerns."
http://en.wikipedia.org/wiki/30th_Street_Station
Whose decision would it be to re-open this tunnel? I've always been surprised they're not connected underground.
I’m not quite sure if SEPTA or Amtrak owns that tunnel, but the portal on the Amtrak station side now has Bridgewater’s Bar on top of it, so it would be a significant disruption to reopen the tunnel to the public. On the SEPTA side, you can see the stairs down to the passageway underneath the stairs up to street level at the Northwest corner of 30th and Market.
Honestly, the decision to close the tunnel was correct at the time. It’s too far from SEPTA-side cashiers and Amtrak-side shopkeepers, and there’s no good sightlines into the tunnel, for it to have eyes-on-the-street security. Today, the option of cheap cameras supplementing occasional foot patrols exists, to possibly provide a middle ground between 24/7 patrolling and closure. I would recommend separate cameras, controlled by Amtrak PD, SEPTA PD, and PPD, for operational clarity and redundancy.
There is one very good side benefit of the closure, although I will be the first to admit it doesn’t look like a benefit when you’re there: because all connecting passengers have to cross 30th Street on the surface, it creates a large flow of foot traffic across that intersection, which helps calm traffic coming in from I-76 and re-acclimates drivers to the city street grid. That’s a hard benefit to quantify, but it’s there. It also tends to create a lot of delays for vehicles coming off of 30th Street, thanks to aggressive mass jaywalking, which I approve of, because jaywalking is the sign of a civilized society. Unfortunately, buses also get caught in those delays. Can’t win ’em all…
Sic Transit Philadelphia 
Umm, you’re kidding, right? I’m supposed to be happy about having to cross 30th and Market because it’s my job to calm the traffic. I should be thankful about the opportunity to perform this public service while navigating through rain/cold/slush/etc., often with luggage. There are plenty of existing underground passageways that are more desolate than that tunnel would be — under Market from 13th St. to BSL, and for that matter the diagonal cut from Suburban Station to the Clothespin area in the evening after the shops are closed. If reopening the tunnel is really a problem, how about an enclosed foot bridge over 30th St.?
I use to use that connecting tunnel all the time in the late 70s and early 80s. SO convenient in inclement weather. Would love to see it reopened.
At this point reopening it is likely to require installation of elevators. Which would probably make it nicer. There’s got to be a way to do this, though.
This tunnel had been approved to be opened by 2020. Very excited this finally came to fruition!