Just throwing this out there, but how about Philadelphia Transportation Co.?
Seriously though, I think Septa is a pretty cool sounding name as far as American transit systems go, and hands off the shield - it's badass and classic. Like I've mentioned before though, having a top-notch system identity with smart stylish branding and a unified simple systemwide aesthetic seems to be a real challenge for Septa. They should hire a talented industrial/graphic designer to help them with this. I think when the time comes to replace the Kawasaki cars with more modern tram stock, this may be a component.