From the PATCO website:

Released: 7/7/2005

DRPA/PATCO SECURITY STATEMENT

Following the attacks on the London public transit system today, officials at the Delaware River Port Authority and PATCO High Speed Line at approximately 6:15 a.m. began to activate increased security at all DRPA facilities including the PATCO High Speed Line and the Benjamin Franklin, Walt Whitman, Commodore Barry and Betsy Ross bridges.

Our customers today are seeing increased police presence at all of our PATCO stations on the platforms, in the station lobbies and in parking lots as well as along the PATCO line. We have activated our K-9 Unit to patrol the PATCO line as well. In addition to the increased police visibility, DRPA has activated a number of security measures that will not be detected by the public.

We will continue to be in constant contact with law enforcement authorities both locally and nationally to keep up-to-the-minute on the situation as it develops.

Since September 11, 2001, DRPA and PATCO Police have been on high alert. We have increased the number of police officers, conducted several security drills and introduced a number of specialized police units such as the K-9 Unit to further our security efforts.

The Delaware River Port Authority is a regional transportation and development agency. DRPA owns and operates the Benjamin Franklin, Walt Whitman, Commodore Barry and Betsy Ross bridges, and the PATCO High Speed Line, the AmeriPort Intermodal Rail Center, the Philadelphia Cruise Terminal at Pier 1 and the RiverLink Ferry.

Number of police vehicles I saw outside PATCO stations today on my way both in and then back from the 15th street stop: 4.

Number of stops where I saw police vehicles: 1 (Ferry Ave, coming home).

Number of actual police officers I saw during the entire trip: 2

Number of actual police officers I saw at PATCO stations: 1, getting in his car to depart the Ferry Ave station.

I don't feel entirely safe on the SpeedLine, but that's becuase I'm an 18-year-old female and there are many crazy and/or not-kind people in this world. Some of them, who I've thankfully never encountered, would have no qualms about trying to alleviate my burden of my purse, wallet, MP3 player, or doing worse.

The reason that I don't feel safe has absolutely nothing to do with the fact that some lunatic, on their own or with a fringe group, could theoretically blow up the train. I'm certain they could do a substantial bit of damage, too, especially if they did so on the Ben Franklin bridge. However, why are we increasing security right now? I'm no expert but I do have common sense (which some government/military officials certainly seem to lack), and common sense tells me that a terrorist bombing in London does not in any way mean that someone is going to try to repeat that the next day in, say, Philly.