Monday, May 14, 2012

Swampoodle Connection

Web of lines
The Swampoodle Connection was originally proposed in the early 1980s to link the Chestnut Hill West Line (R8) into the SEPTA Main Line--originally the Reading's 9th St. Branch--via the Manayunk/Norristown Line (R6) where the two lines closely parallel each other just south of Allegheny Ave. between the SEPTA Main/R6 line/Northeast Corridor junction complex and the lightly-used Allegheny R6 station. (A disused CHW station sits nearby; you can see its ruins as you pass by.)

CHW was originally owned and maintained by the Pennsylvania Railroad (PRR) and as such accessed Center City via the PRR's right-of-way, nowadays the Northeast Corridor, via Zoo Interlocking and 30th St. into Broad St. Station, nowadays Suburban Station. This routing is highly circuitous and adds a good ten minutes to the line's schedule. It also involves a flat junction across the NEC, such that its outbound trains foul the entire Corridor; this has the side effect of inhibiting its schedule frequency. Clearly, a reconsideration of the Swampoodle Connection is needed in order to optimize existing services.
Phase 1. The dark blue represents the Reading lines, light blue the PRR. Orange is the first junction.
Doing this is relatively simple: a flat junction between the two lines where they are more-or-less level with each other just south of Allegheny station. This moves the primary flat junction to the easier-to-dispatch SEPTA Main, as seen above. But this is not the only use of a Swampoodle connection; rather, it is the beginning of a complex.
Phase 2. The yellow line represents the extensions.
The next step would be inaugurated by the, well, inauguration of diesel commuter rail from Norristown to Pottstown (or even Reading). While the traditional Schuylkill Valley Metro project is deader than the dinosaurs, there is no reason a basic diesel push-pull service would not do well. After all, that was how the Reading (and later SEPTA) ran the line for many years! Such a quick-and-dirty restart would necessarily terminate in 30th St. Station's lower level, but utilize the former Reading main line, and hence would necessitate a second connection at Swampoodle, this time going the other way--from the R6 to the NEC. Phase 2 accomplishes this by using the former interchange track as well as the original R8 flyover; the Phase 1 junction becomes a full crossover.

The problem with this is, of course, that it would (again) create a fouling situation on the NEC, on top of being (again) an extremely circuitous entré into Center City from the north. On top of this, restarting commuter rail along the Reading main is an excellent skeletal framework for reconsidering the (underutilized) Stoney Creek Branch as a route into the city from the North Penn area, as well as the (currently a trail) former Perkiomen Branch, which would offer improved access to towns up the Perkiomen Creek Valley, most notably Collegeville-Trappe, Graterford, Schwenksville, and the Pennsburg-Green Lane-Red Hill area. Passenger service along the Reading main also offers the promise of electrification--to Phoenixville, in particular, shows promise--and possibly eventually Pottstown.
Phase 3: the red line superimposed on the previous works.
While the majority of the issues, longer-term, would be solved by reactivating the Pencoyd Viaduct (more on that later) and converting the former PRR Schuylkill Branch, the remnant of which is the Cynwyd Line (R6), into a cutoff linking the Reading and PRR main lines and offering a much more direct entry into Center City from the northwest, locals to Norristown (Phoenixville?) and CHW will still be wanting to use Swampoodle. Phase 3 thus seeks to eliminate the flat junction between the SEPTA main and the Norristown Line, utilizing the former CHW alignment and the infrastructure of the previous two phases' interlocking. Phase 3, the most expensive addition to the Swampoodle complex, would involve cutting a shallow trench tunnel from the CHW's North Philadelphia station under the Trenton Line's and through a Pathmark parking lot into the SEPTA main line. This would convert the basic interlocking achieved in Phase 1 into a fully high-speed junction.

If management wishes, a shallow tunnel can also be cut under the NEC in order to grade-separate the northbound junction at this phase (especially if Swampoodle can be achieved before Pencoyd), in order to offer full operational flexibility--even though the Norristown Line-to-NEC side of Swampoodle would have significantly less usage than the SEPTA-Main-to-Norristown-and-CHW-Lines side. Once Pencoyd is up and running, the Norristown-to-NEC side will be more a secondary path to be used mainly if the primary Pencoyd path has to be closed for any reason.

Swampoodle, like Pencoyd, is a potential interlocking with regionally-important implications. This post is intended to be a laying-out of a program to develop it to its full potential.

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