Atlas deck truss bridge modification

[davefoxx]

JDB,

Here's what I did in a similar circumstance.  I flipped that Atlas through plate girder bridge upside down and glued a piece of styrene to the bottom (now top).  I glued two small pieces to the sides of that piece of styrene as curbs to hold the ballast on the deck.  I painted the bridge silver and the "trough" a [poor] concrete color.  I installed the bridge on two Chooch abutments, which I cut a course of block out of where the bridge sits to get the proper depth.  My radius was also around 13-14".  I installed the track and ballasted right across the bridge.  Oh, when I set the height of the bridge, I made the deck even with the top of the cork roadbed, so the track could flow right across the bridge.  You could set the height so that the cork goes over the bridge, but, in my case, I was worried about the depth of ballast being too deep.

I don't think that I even pulled the rails out of the Atlas bridge, so if you got at a low enough angle, you could see the old "track" on the underside of the bridge.  But, this was at an extreme angle that did not show under normal circumstances.  I think I was the only one who knew it was there.



Hope this helps,
DFF

[Bsklarski]

Dave Fox has a good idea there use an HO bridge, as it is wider for the curve and you can find one that is short and thin. My idea was move that RH switch to the left onto the straight section that runs the long side of the door, just after the curve, run that siding all the way around the top curve and down part way the other straight edge and tie it into the main up past the other bridge. this in turn will give you a longer passing siding and basically make the only "single track" portion where the two bridges are and in between them. If you place your other sidings correctly off the main siding, you can run a train on the main nonstop and run another train on the siding working other sidings located off that. Dont forget to cut in a switch somewhere else so you can add or install staging. Believe me you WILL need staging 

[nkalanaga]

Shark_jj:  Thank you!  Yes, the valley itself is a poster from a photo I took from the old highway bridge over the Spokane River in Post Falls, ID, below the dam, looking north towards I-90.   The Interstate gives a nice flat edge to the top, and I cut it there, except for a few trees.   Oddly, the river on the layout is flowing towards the camera, and in the photo away, but the current doesn't show, so it all works.

That part lines up with the 3-D scenery on either side.  Above that is the main backdrop, which here is a series of photo posters taken looking more-or-less north from near Silver City, MT, on the Great Falls - Helena GN (BNSF) line.  Since that's where the scene is supposed to be, it's a perfect match!  However, there's no river there, as I modified the geography a little.  Geologically, there once was, eons ago, and there could be today, if there was enough water. 

The sky is the back side of a roll of vinyl flooring painted blue.  The foreground river is a much better match looking down, in person, and when I get the front panel on (someday) the edge won't show.  It's a piece of hard plastic "floor protector" that went under a roll-around office chair, and has a very nice "water texture" on top. 

This is the third layout for the bridge, and the second for the plastic river.  The rest of it is still in our "junk shed".

[vt_railroad_guy]

DFF, the more I look at your bridge, the more I like it.

[nkalanaga]

Agreed.  I've seen deck bridges on curves done just that way.

[Ian MacMillan]

Curved tracks on a steel truss bridge would be highly unusual, and wouldn't look right to me--but I am sure it's been done!

The B&M did it so often that straight track on a truss bridge looks odd!

[nkalanaga]

The Milwaukee had a fairly sharp curve in a through truss in Western Washington, with overhead wires no less.  The bridge was considerably wider than normal, and did look a little odd...

[Bsklarski]

The B&M did it so often that straight track on a truss bridge looks odd!

Two I can think of off the top of my head is the old bridge at Brattleboro VT that went over to New Hampshire and another on the Conn River in Holyoke.  It is very much an S curve. The spans on both sides of the trusses are straight and set up on the piers so its basically a curve. Interesting note is the bridge ties. Each one was cut to fit, stepped in such a way to make super elevation in curves. I can say it must have been a major task to do each one. Sorry about the picture quality, but I took that with a cell phone a Canon point and shoot. I shall return there one day when I bid back to Brattleboro perhaps this summer.

[nkalanaga]

That's even worse than the MILW's Cedar River bridges.  They at least kept it to a simple curve!  Bridges on curves really weren't uncommon.  The prototype isn't going to put a straight section in just to make the job easier for the B&B gang.

[wm3798]

I spliced two of the Atlas deck trusses together to get a rectangular shape and the length I needed, and I used Micro Engineering 40' deck plate spans to effect the curve.  Part of the trick is to run a slightly tighter radius in the approaches to the bridge, then you can use a gentler curve to get across the gap.  Sometimes we modelers get hung up on our uniform radii and flat and straight right of ways.  If you spend some time out in nature observing what REALLY happens when a railroad gets built, you'll find all kinds of interesting solutions to geological problems.





Lee

[Bsklarski]

I love that scene Lee, It came together very nicely.

VT railroad guy, just remeber the golden rule, the rails cannont be outside the main beams or girders of the bridge no matter what

[pnolan48]

Two I can think of off the top of my head is the old bridge at Brattleboro VT that went over to New Hampshire and another on the Conn River in Holyoke.  It is very much an S curve. The spans on both sides of the trusses are straight and set up on the piers so its basically a curve. Interesting note is the bridge ties. Each one was cut to fit, stepped in such a way to make super elevation in curves. I can say it must have been a major task to do each one. Sorry about the picture quality, but I took that with a cell phone a Canon point and shoot. I shall return there one day when I bid back to Brattleboro perhaps this summer.

Oh wow!

Is that bridge still standing? If so, in Brattleboro or Holyoke? I think the alignment of the bridge piers is also interesting, but I can't tell what's on the right, off the image. It's worth a special trip to see it when I'm east in early July (if it's still there).

I should modify my observations to say that long-span bridges were rarely build on a curve. I'm seeing that short-span bridges, or long bridges with multiple short spans are indeed built with curves!

[Zox]

Is that bridge still standing? If so, in Brattleboro or Holyoke?

I think this is it:
http://www.bing.com/maps/?v=2&cp=42.83748931802123~-72.54600429704524&lvl=18&dir=0&sty=h&where1=Brattleboro%2C%20VT&form=LMLTCC

Unfortunately, the birds'-eye view doesn't bring up additional detail in this area (it just tilts the overhead image).

However, Google Maps offers an insane level of close-up here:

http://maps.google.com/maps?q=Brattleboro,+VT&hl=en&ll=42.838147,-72.546187&spn=0.000932,0.000945&sll=39.099275,-76.848306&sspn=0.126291,0.121021&oq=brattle&t=h&hnear=Brattleboro,+Windham,+Vermont&z=20

You can actually see the space between the guard rails and the running rails. 

[Ian MacMillan]

Yes that's Brattleboro and it is still standing.  It was double track. There are also some along the B&M NH mainline like the one in Nashua, NH that was triple track (3 single track bridges side by each)

[nkalanaga]

Brian:  Keeping the rails inside the supports has always been my rule, simply because it looks stupid otherwise.  Good to see that it actually IS a rule!

Years ago I built a deck girder bridge for a curve.  Nothing special, about 60 ft long, but the girders are on nine foot centers.  It wasn't any harder, and looks much better, than the narrower one I tried first.  It's still in use on my latest layout.