In the 1880's Pittsburgh industrialists conspired with the Vanderbilt Organization in an attempt to undermine the transportation services of the Pennsylvania Railroad. The enterprise, known as the South Pennsylvania Railroad would attempt to construct an alternative rail alignment along the southern tier of the state. As this route lacked a natural waterway to break through the various mountain ridges it would have to rely on a series of 9 tunnels to forge its own path. Work on these tunnels as well as other grading along the right of way commended in 1881, but by 1885 Vanderbilt was learning why the name brand Pennsylvania Railroad had followed the sinusoidal path of the Juniata river. Even with the tunnels and generally favorable conditions for the 50 miles in the Cumberland Valley west of Harrisburg, Vanderbilt faced the reality that even if the South Pennsylvania Railroad were completed, the result would be a lackluster alignment beset with sharp curves and steep grades. The solution was to admit defeat and declare a truce with the PRR, exchanging the SPRR right of way for the PRR's interest in the budding NY Central competitor West Shore Railroad.
For the next 50 years little was done with the SPRR right of way and in a move that may have ultimately proved short sighted the PRR sold it to the newly established Pennsylvania Turnpike Commission in 1938 for conversion into the nation's first inter-city limited access motorway. The most attractive part of the alignment for the Turnpike were the 9 mostly completed tunnels, with 7 being incorporated into the final design. Motor vehicle technology of the time made hill climbing particularly fraught and allowing 1930's cars and trucks to blast through mountain ridges at grade was critical to the highways success connecting the Pittsburgh and Philadelphia markets. However as motor vehicle technology and highway demand increased over the next 30 years, some of the tunnels became both less necessary and increasingly congested. The result was a bypass plan that would replace two tunnels just east of Breezewood, PA and a third at Laurel Hill with new alignments and open cuts. In 1968 13 miles of the original turnpike near Breezewood was abandoned in place and for the next 40 years it remained a curiosity for urban explorers. In 2012 it was re-opened as a bike trail with full access to both tunnels and their related support structures and in 2020 I was able to document the complex with the resulting photographs available here ( mirror ). Also included are some rail photos from Hagerstown, MD.
The abandoned section of the PA Turnpike included both the longest, Sideling Hill, and shortest, Rays Hill, tunnels on 8 tunnel system including the Northeast Extension. The first 4 miles of the abandoned section starting from the eastern end is still owned by the Turnpike Commission with parts being used for storage and police training. The eastern end of the bike trail is adjacent to the abandoned Sideling Hill service plaza, however that is pretty much just a parking lot with nothing to see. The first point of interest is the 6782 foot long Sideling Hill tunnel.
The intact 1938 tunnel portals show off the Art Deco design along with unsmoothed concrete facing designed to imitate the aesthetic of local rock formations. It is important to remember that this is a railroad tunnel adapted for automotive use and the original design makes that a bit more clear.
The headhouse located at each portal used a common design with a two story support building built into the left side of the abutment and a fan plant located on top. The support building consisted of a loading dock on the ground floor and general repair and mechanical room on the intermediate level. Here we have a view of the westbound Sideling Hill tunnel's loading bay with the door providing access to the tunnel.
Each support building had an internal staircase that in most cases have completely rusted away at the base making their use impractical.
Therefore access to the fan rooms is obtained by walking up the slopes adjacent to the headhouse and then circling around behind to enter via the stairs at the rear of the fan plant.
Located on both ends of the fan plant are two e-motor rooms where the electric motors that run the fans were located and maintained.
Each plant has two fans of the squirrel cage type that would provide positive pressure to push the noxious automobile exhaust fumes out from the main portals.
Each fan house provides access to a plenum that runs above the complete length of the tunnel to distribute the fresh ventilation air. Also visible are the remains of a metal trackway that runs just to the right of the plenum centerline. The railroad nature of the tunnel is even more apparent from the profile of the tunnel's true ceiling.
The slab of concrete diving the plenum from the roadway is supported in part by steel rods extending down from the ceiling.
