Bridge on a curve, solution?

I'm going to begin laying track this week on my new layout and totally over looked the bridge over the highway. It's right in the middle of a 2MT curve with 1.5in spacing. How do you tackle this problem? I was looking at Atlas's plate grider bridge, is it possible to fit the curve on that bridge. What options are out there. Thanks in advance.

 

My first concern with a curved bridge is the clearances needed for the overhanging portions(s) of locomotives and rolling stock. The longer the equipment and the tighter the radii... the more clearances your have to accomodate. If the bridge will be a trestle type... without vertical surfaces along the sides... the clearance issue is not a factor. The plate girder bridge has vertical surfaces and is rather narrow, giving you little room for curved trackwork.

 

An option would be to build the bridge with a piece of wood, carefully taking into consideration car overhang on the curves (you can run your longest cars through the curve and mark their spots, just to be safe). Then cut the sides off an Atlas girder bridge and mount those to the side of the wood. You could also mount them below track level, basically in a deck girder bridge style, then you won't have to worry so much about the car overhang. But this method would require the underpass being lower to clear the bridge deck.

 

Build a stone arch bridge:

 

I haven't yet built a bridge on a curve, but I have cut the floor out of the Atlas plate girder bridge and built a new floor with Styrene H beams and Angles to stagger the girders to span a roadway on an angle. Make it wide enough to clear your longest equipment. Use stripwood to make a wooden walkway. Or you could use 30 or 40 thousandths styrene to make a solid floor that can be ballasted.

 

What's your vertical clearance over the highway?

If there is a 'typical', it is that a railroad will try to put on a deck girder, not a through girder, in a series of shorter spans. Only the critical span that has a vertical clearance problem over the highway might be another kind of structure like a through girder. And mostly, just widened out.

Taken to complete excess, consider the SP bridge at Redding, CA: http://blogs.lib.ucdavis.edu/specol/files/2011/05/train.jpeg
That's a monster, but same idea. Deck girder, series of spans, slightly widened, fully curved. Notice the 'spread legs' on the piers.

I have a nice shot of the curved girder bridge on the PRR in Irvine (Irvineton) PA, you can see it in Google Earth - it was a two track, three-span bridge over the Brokenstraw creek and one track remains. On one end it goes over a road - and there is only SEVEN FOOT clearance under it, trust me, that's why it is a through girder. It is simply widened out. The bridge basically has three straight spans on a curve, widened out for clearance and spacing.

The bridge is still a clearance problem on long dimensional loads today. I've got some nice end shots of it if you decide that's a prototype you want to focus on - PM me. It's about seven miles away from where I live.

 

I saw an N-trak corner module once that had utilized HO scale bridges. It looked fairly convincing.

 

You may be approaching this from an angle that will be creating more problems. Are you working off a track plan? If so, can the plan be altered a bit to allow for a straight run on the bridge? It looks like you are doing only one 6" or 6 1/2" bridge. Perhaps extending the layout six or eight inches on one side will alleviate the problem? I had a similar problem with adhering to a track plan which created a steeper grade than what would be desired. If I extended one side by a foot and a half, there would have been no problem.

I know there is a desire to get that track down and run a train. Be patient and explore other alternatives. If you have proven skills in doing what is suggested above in the thread, go ahead. If not, you will be filling your frustration quotient rather quickly.

 

I had a similar situation but solved it using Kato Unitrack curved viaducts. They come in double track spacing radii too. They also make, I believe (but don't quote me), a double track curved viaduct. I know they make the straight ones in double.

I've also seen a photo of a plate girder bridge (like the Atlas one above) on a Chicago railroad. Although not on a curve, per se, there was a sharp curve just before crossing the bridge. The railroad alleviated the rolling stock overhang problem by trimming the end of the vertical plate on the inside of the curve.

Wish I could remember where I saw it though...

 

Get a double track bridge, redo the deck for just one track with the center of the curvature of the track in the middle of the bridge. Should work with not a lot of fuss.

 

I have 2 1/2in from the bottom of the roadbed to the highway. This curve is the only place the road can go.

 

I apologize, but I'm sure if I understand this statement, so maybe my reply was not very helpful. Is that 2 Mainline Tracks on a curve spaced at 1.5" apart?

I guess we haven't really asked you some of the most important questions about the 'use' of this portion of your layout. First... what radius will the curved track be at the bridge? What kind of locomotives and rolling stock will be the predominant use on this part of the layout. The reason I bring this up [from my own experiences] that often we fill an area with trackwork without realizing what we are actually going to run on that trackwork... pretty much what Fotheringill mentioned... and the topic of many of his "Lessons Learned ".

2.5" between highway and bottom of roadbed might be enough to do a credible deck girder (as mentioned b Randgust). 2.5" equates to an N scale vertical clearance of about 33' prototype... and most prototype clearances are 14' to 18' for railroad bridges over a highway... sometimes less as noted by Randgust. Will the span of the bridge be buttressed on each end with retaining walls or will this be on bridge piers which gradually ascend and decend?

 

Calzephyr-

You have captured the essence of my pain and my desire to see others NOT in the same position.

It took me about a year and a half to find Trainboard. Since then, I have asked first and done later. Lately, I have NOT:

1. strictly adhered to a trackplan (I originally was faithful to the 30+ year old Atlas N-17 plan).
2. assume every train will run on every piece of track, curve, turnout and grade before permanently laying the track.
3. Continued with my original "monkey see, monkey do" approach to wiring and have attempted to understand the basics.
4. Dropped hot solder on my chest while under the layout soldering, completely ignoring some dead great thinker's ideas about gravity.
5. thought I could handle an airbrush like I have been working in a nail place for a decade or two.
6. attempted to make decals on white paper trying to match RBG mixtures.
7. dismissed chalk weathering as being temporary and easy to rub off.
8. ever again attempted to dismantle and reassemble a steam engine. I now know my personal limitations.
9. assume I can still work without an Optivisor.
10. done a lot of other stuff that had, in the past, filled my frustration cup to overflowing.

 

Thanks for the advice guys. I found the Monroe Art Deco bridge http://monroemodels.us/9003.htm. It looks like it wont have a problem for my application and if I have to I can cut it and widen it. Has anyone here dealt with this kit?

 

this is a sample of custom made bridges by David Stockwell. a very nice older gentleman who's been model railroading a very long time. i don't think he's on this site, so i had to link him form another. he does beautiful work at a great price in whatever scale you need. sorry i can't find his phone #, but he can be contacted through this link

http://www.modeltrainforum.com/gallery/showimage.php?i=2248&catid=member&imageuser=3233

i don't have any interest in these bridges except thinking more of them need to be built

 

I saw a easy flexable bridge the other day. Basically the roadbed for the bridge is in small 1 inch sections and each section is connected to the next by a single screw. This allows the bridge deck to be in any shape. Then you just add the piers.

I am trying to find what the product was called. More to follow.

 

Another possibility and one not often modeled is having the railroad on a fill and the road tunneling underneath. This a very common way of having a road underneath a large railroad fill. Try googling "Railroad underpass" for some other ideas.

http://www.dhr.virginia.gov/registe...-0573_Virginian_Railway_Underpass_VLR_4th.jpg

 

Yeah, I was thinking about this before. This is how they did it when they took out many of the grade crossings where I lived. Here's a link to Google's street view of one of those crossings. The view is facing the underpass with a two-track mainline crossing over at ground level. Notice how they used concrete sides and just dropped the road underneath.

 

wow, I love this layout it's something that'll fit into my small bedroom.