Just west of the Lewistown station is the first of many crossings of the Juniata river. This, the Granville Bridge, is home to the west half of LEWIS interlocking. The tower was just east of the bridge's end. In that the PRR Middle Division in HO Scale includes LEWIS interlocking, this spectacular bridge will be modeled.
Following my methodoloy for the Sherman's Creek bridge on my former N scale model railroad, I will be building the Granville Bridge on the workbench, as a "module" to place into the benchwork at its final resting place. This provides a lot more accessability and allows me to work on the project concurrent with other layout areas -- specifically Altoona staging and JACKS interlocking. By working in parallel, there will be less left to do when I actually get to working on the LEWIS section of the railroad.
When reviewing specifications of the bridge via the Library of Congress and other online sources, I found the Granville Bridge to be remarkably similar to the Rockville Bridge, just shorter. The Rockville Bridge featured a thicker abutment pier every eight arches for added strength; the Granville Bridge contained one, in its center. Consider the following measurements:
|Length||624' 0"||3,791' 0"|
|Width||56' 0"||52' 0"|
|Number of Arches||8||48|
|Arch Width||70' 0"||70' 0"|
|Arch Radius||40' 7.5"||40' 7.5"|
|Arch Rise from Springing to Crown||20' 0"||20' 0"|
|Rail Bed Height Above Arch Crown||7' 0"||7' 0"|
|Pier Width||8' 0"||8' 0"|
|Middle Pier / Abutment Pier Width||16' 0"||19' 0"|
Upon realizing how close these two bridges were designed, it was a "no brainer" to contact Bob Jans for a custom version of his Rockville Bridge kit just prior to his retirement from Model Railroad Stoneworks. I purchased eight arches with one abutment pier. My Granville Bridge will be four feet narrower and three feet longer -- attributable to the center pier -- than the prototype. Given that this is HO scale, I'll challenge anyone to call me on it!
The Granville Bridge also features 3' 0" by 16' 0" corbeled projections from the spandrel walls, providing safety areas for personnel on the ground. I will have to scratch build these features.
Over the coming months I will post status updates on the bridge's construction.
You can view more photos of the prototype bridge here.