Gateway from the West and North
Though Rockville Bridge is a well noted landmark on the Pennsylvania Railroad, the entire facility associated with that name deserves a close examination. The junction, simply know as Rockville was a complex interlocking that was essentially shaped like a large "H" on both the east and west Side of the Susquehanna River, the bridge spanning the river in between. From the west on the mainline, Banks Tower in Marysville, would set up traffic to Rockville for a number of different scenarios. The two most common, freight arriving or leaving Enola Yard, or traffic to and from the bridge and Harrisburg. At Banks the complex junction began with running tracks dropping below grade between the mainline, essentially "ducking under" the route to Harrisburg so as not to interrupt traffic flow at the west end of Rockville Bridge. This simple concept that we now take for granted in highway construction was something that the PRR developed to keep passenger and freight traffic fluid while sharing the same track system.
Rockville West as it was sometimes referred to, was the more complex and remote part of the junction, providing connection with the massive Enola Yard complex, at one time the largest on the PRR system. The mainline and yard leads to Enola essentially run North - South here along the west bank. At Rockville West the mainline comes up and over the yard leads and turns left onto the beautiful Rockville Bridge, the third bridge built here by the PRR. Much of this infrastructure including the early Enola Yard, flying junction, and the Rockville Bridge itself, comes from a landmark improvements project under the leadership of PRR President Alexander Cassatt, and Chief Engineer William H Brown. The trademark cut masonry retaining walls, bridges and brick lined tunnels are beautiful examples of Brown's preference of these materials, and have become a case study for his belief that this construction style would last a very long time.
Opened in 1902, W H Brown's Rockville Bridge is the longest masonry arch railroad viaduct in the world. Taking three years to complete the 3820′ long span is made of 48 seventy foot arched spans over the Susquehanna River. At the base of the west abutment the "B Track" was added in 1939 to allow Enola traffic access east to the Harrisburg Yard and more importantly the Northern Division by way of the line to Northumberland.
On the east bank of the River there was a uni-directional crossover from the Eastbound #1 Track to Westbound #4 Track, and connection to the north leg of a wye that provided access to the line to Williamsport. Continuing to the East the other side of the cross-over from the Williamsport lead across to #1 track allowed traffic on and off the Williamsport Line from the East. Inside the area of this junction sometimes referred to Rockville East stood the interlocking tower. Originally built in 1898, it was the third in this general location, originally utilizing a mechanical plant to control switches and signals. In 1942 the interlocking complex was rebuilt with a standard Model 14 Union Switch and Signal 43 lever elecro-pneumatic interlocking plant. The tower lasted into the Conrail era until 1986 when it met its demise with Conrail's efforts to close towers and implement Centralized Traffic Control on the former PRR lines.
Today this bridge and a scaled down version of the Rockville Interlocking still faithfully serves the Norfolk Southern Corporation seeing heavy freight traffic and a round trip of daily Amtrak NYC-Pittsburgh service. While the track layout has been altered over the years, changing from the original 4 track system, to three, to the current two track layout, the approach infrastructure and the bridge’s appearance is still just as impressive.