I like the idea VZ. The only potential drawback I see is the noise from more frequent and potentially 24 hour service going through Mt. Airy and Chestnut Hill. Living near a rail line can be a turn off to potential home buyers who imagine they will hear the train all night. The current commuter trains don't run overnight. Although most persons tend to get used to trains and "don't even hear them" after a while, it could take a bit of convincing to get some on board. I personally love the idea. It would be relatively cheap considering the existing infrastructure.
Another potential idea using existing right of way would be to utilize the Chestnut Hill East line north of Wayne Junction. The area served by the CHE is more densely populated and more dependent upon public transportation. Instead of travelling to Broad and Olney, residents of East Germantown, West Oak Lane, and East Mt. Airy could use the new line (as many currently do with the existing line). Using the CHW would require a new flying junction to built into the BSL. Flying junctions already exist north of both Olney and Erie stations which could be used to connect to the CHW. Yes, the extension between the two would much longer than the BSL and the CHE line. While I understand that cost was your main driver, building an underground flying junction on an existing subway line in an area sandwiched between the NE Corridor and Reading Main line would still take some serious work. Or the flying junction could be built just north of Glenwood Avenue and meet the CHW line somewhere around 17th and Clearfield Streets.
I'm all for replacing some of the commuter lines with high speed lines. However, if I had my pick I would have the Blvd route 1 line running under the blvd all the way to Neshaminy. Not only would it ease traffic on route 1, but it could relieve some stress on the Trenton and West Trenton lines if a park and ride were built near the city line. In my mind it would be worth the 10 billion dollar investment. Let's take the 7 billion needed for I-95 and put it towards a new subway line. I'm sure that will go over well in Harrisburg and Washington.
