Beaver Railroad Overpass Model Railroad Bridge

This is an HO scale model of the CSX railroad bridge over the Norfolk Southern railroad in Beaver County, Pennsylvania.  It was built in 1909 and is still in service.  The bridge can carry 4 tracks over two separate double tracks.  The model was developed using information from HistroicBridges.org and Google Maps in Fusion 360.

For more information and photos of the bridge, follow this link:

https://historicbridges.org/bridges/browser/?bridgebrowser=pennsylvania/beaverrailroadoverpass/

The bridge in HO scale is 2' 10" (860 mm) long, 8 1/4" (190 mm) wide, and 4 3/4" (122.5 mm) tall, with a 3" (75 mm) offset.  Print two of each body to make a full bridge.  The approach arches will need to be split in PrusaSlicer to fit on the print bed.  Since the bridge can also be shortened by removing the extension, and where to split depends on the width and offset, I didn't feel it was helpful to force a split there.

For other information such as background and print settings, see my Ottawa River Bridge.  Per PrusaSlicer this bridge should take about 2.1 kg of filament to print.  

This is the second model in this series, and incorporates parametric modeling.  Parametric modeling unlocks the power of 3d printing by enabling the model to be adjusted to the specific needs of a layout.  The model was developed using the free version of Fusion 360 since it is for hobby and non-commercial use.  If you open the model in Fusion 360, under the Design  workspace - Modify/Change Parameters you can change the Width of the bridge and the Offset (from perpendicular).    For example, if the offset is zero then the lower tracks are perpendicular to the upper tracks.  If the offset is equal to the width then the lower tracks are at a 45 degree angle to the upper tracks.  I included a diagram but I don't need to explain more because you can just change the numbers and see the model change.  The height and length of the bridge cannot be changed because the geometry of the sides was too complicated (at least for me).  The model is in mm because I am ‘mercan and understand feet, inches, and fractions of an inch, but decimal inches mean nuthin’.  Millimeters are much easier to work with and translate better to the 3d printer.

The prototype bridge appears to have been built for four tracks on top (there are only two tracks there now).  You can also reduce the width and just have a straight double track on top.  As with the Ottawa River bridge, this bridge would really benefit from a well done paint job to highlight its features.

I did a test print of the bridge at N scale, reducing the width to only handle two tracks (mostly to test the parametric modeling and to reduce filament), and at this scale it would require 240 grams of filament and 40 hours to print.  I only printed one side since I could confirm everything I could think of checking was ok.  Included are photos of how I clamped it while glueing and also the finished test print with a light coat of white spray paint so that the details are more visible.  

Edit 10/1/2022 - lowered the ballast deck, so the parapet is slightly raised to match prototype.