My two level track arch bridge project

I drew the arch portion to scale on brown wrapping paper over a piece of puzzle board. It’s hard to see the lines but click and enlarge. I will cut the 3D printed beams to these sizes to make the arch. It will be crossbraced based on photos I have of the New River Bridge and on a book I am referencing: “Model Railroad Bridges and Trestles: A Guide to Designing and Building Bridges for your Layout” by Bob Hayden.

Here is the first arch assembled. I will make an exact copy of this arch using the template and first arch. Then the two arches will be attached together and cross braced.

I’m the previous photo notice that the larger beams are a grayish color. These are the 3D printed beams of various sizes. The white beams are various sizes that Ali already had an inventory of from Evergreen. It just so happens that some of the 3/8” I beams from Evergreen fit perfectly in the grooves of some of the printed beams. Got lucky.

Trying to get caught up with where the project is currently so here are some more photos of the arch portion progress. Have begun attaching the two arch structures together at this point.

In these photos I have finished the cross bracing on the two arches I’m ready to start the upper portion onto which the modified Pratt Trestle will be placed.

We have made it to where I am currently at in terms of construction. I have finished placing all the gusset plates at beam junctions. I think these plates give the project some realistic detail and they also make the structure that much more rigid. I have carefully cut and adjusted the vertical supports for the flat portion that will hold the modified Pratt Trestle. I need to spend a couple days 3D printing more large beams. Made too many mistakes hand fitting all the beams to this point and uses up my supply……lol. Hoping you can begin to see what at least the bottom arch portion of this bridge project will look like. I’m planning on a coat of gray primer and then flat rust color topcoat fairly close to the New River Gorge Bridge color for the entire bridge project.

Impressive.

I think you have done a great job in design and construction.

Fantastic work, Poncho. Keep the updates coming.

Update on progress

While I am printing more beams for the arch structure, I decided to work on the upper truss portion of the bridge. I am using an Atlas 40” Pratt Truss kit (the black portion of the truss in the photos) and bashing it make a double decker bridge. I have started by adding printed beams on the sides of the atlas truss to square the structure. I was able to design and print these beams the same dimensions as the main beams in the atlas truss bridge. I think this will look more uniform once primed and painted.

I then began placing the substructure and girders that will support the upper train track. Notice that this portion of the bridge extends out from the Pratt truss bridge as this will interlock with the top level of the layout. There will be pins or some sort of guide mechanism as the entire bridge will be able to be lifted using synchronized electric linear actuators. This will allow guest to walk under the bridge to an inner display area of the layout. It’s all in my head and drawn on napkins at this point…..

Especially for the upper girder and beam support structure, I am referencing: “Model Railroad Bridges and Trestles: A Guide to Designing and Building Bridges for your Layout” by Bob Hayden. I used  his beam layout. The track will be set right on top of these beams in between the side skirt girders. I’m still contemplating placing any crossbracing on these beams as the book does NOT show examples with crossbracing. This design is very strong and should support the upper track and train loads very well as is. Testing will be needed to be sure once the build is ready.