So I’ve figured out how I’m going to model an arched stone bridge–at least from the bottom and sides. But I’ve come up with a couple more questions.
How wide should I make the top of the bridge if I plan on having a dual track run across it?
What does the top of a stone bridge look like? All the pictures I’ve seen are from the side. Okay, my guess is that there are beams running the length of the track and and the ties are nailed to those beams. I would also assume a catwalk of some type at least on one side (although I’ve never seen a handrail). Am I close?
Does any kind soul have a photo of the top of a stone bridge (or even a photo of a model from the top?)
If it is a solid stone bridge, I’d assume some sort of fill on top of the stone, ties, ballast. The stone is going to carry the weight and the ballast will hold the ties just as it does off the bridge. The fill would just sort of level up the top of the stone layer.
Here is the plan for a PRR concrete bridge. It should be about the same, except stone bridges will have batter, that is, be wider at the bottom than at the top.
A stone bridge would almost always be a ballasted deck bridge, so from the top, the only thing visibly different would be stone curbs rather than concrete or I-beams.
The things to replicate from this plan are the 24-inch wide curbing and 78 inch wide min distance from the outermost gage line to the outside of the curbing.
This was a 4-track Pennsy mainline at the time of the picture. You can see the Johnstown Traction Company PCC to the left on Roosevelt Boulevard near the Point Stadium in the 1950s.
The Stone Bridge traverses PA 56/PA 403 on the left, with 2-arch entry to one of the Bethlehem Plants on the right and the original Cambria Iron Company mills that supplied much of the nation’s initial railroad rails, and the Stoneycreek River has a total of 5 stone arches. The bridge deck surrounding the mainline roadbed is stone ballast as if it were the standard roadbed.
The latter link cracks me up. Greater Johnstown is large enough to headquarter more than one TV-network affiliate, and has the only Level One Trauma Hospital between Pittsburgh and Harrisburg.
It’s like I said before and as shown on the the plan. The min distance from the outside edge of the curb to the gauge line of the outer rail should be 78 inches; let’s go with 87 so it will be 1 inch even in HO. The HO gauge is ~.65 and the recommended track spacing is 2 inches between centers. So, from outside of curb to outside of curb you’ve got:
1 + (.65/2) + 2 + (.65/2) + 1 = 4.65 for a double track.
The top should look like any other ballasted deck bridge: two curbs with ballast and tracks between them.
Thanks for the info. I didn’t get the measurements from your previous post because couldn’t make out what the top drawing represented. But I can work it out from your math. This particular bridge is N-scale by the way.
Mr Gindy,
I’ve seen that bridge many times and never associated it with this project. It’s about 45 minutes from my place and I have to pass under it to get to my op session. I guess a road trip is in order.
Some pics of a short stone arched, width adjusted due to the curved track
Carved plaster veneer to match the WS retaining walls. Castings are glue to a 1/4 ply base shape.
A future project of a double track curved stone arched viaduct is to be more of a challenge. I believe this to be more on the lines of what you’re doing. No pics yet, don’t know if the plaster castings are to be formed for the curve or take the simple way out and have the sections just straight and angled to the radius. Curved would look so much better though.
The double track in the forground is the proposed stone arch bridge.
