In this picture, the back track will be hidden behind a mountain/hill, and between there and the existing Truss bridge will be a Micro Engineering Viaduct. I don't really like the single curved track on the double truss bridge and feel the size of the truss bridge will take away from the viaduct, so am thinking of replacing the truss bridge with a single deck girder bridge. Looking for opinions...
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Personally, I'd get rid of the straight section through the truss bridge, go with a full curve and use a trestle. The curve through the bridge doesn't look right. Or, you might try narrowing the "gorge" at that point so you have a shorter straight bridge, like the girder you've suggested.
It takes an iron man to play with a toy iron horse.
Thanks. Thinking of narrowing the crossing there and using an Atlas Plate Girder bridge flipped upside down with ballasted track over it which would allow a slight curve like this:
I have several of that exact same bridge on the existing part as well as for the planned future part of my new layout and I can say without hesitation that bridge does not work in the location where you have it shown in the picture. A prototype would never have a curve on a straight bridge. How would you support the track?, how would you work in the bridge abutment? If you could move the bridge back farther and possibly use a ballasted deck bridge or an skewed plate girder bridge as seen below.
Aralai,
Keep in mind that the railroad will always settle on the cheapest distance between two points. The type of bridge used is frequently, if not always, determined by two factors: the distance to be spanned, and the required vertical clearance below the structure.
A box truss bridge, such as the one you've got there, is probably the most expensive option, but would be the most likely the one used if there was minimal clearance below the structure for say, another rail line or a highway. If the only consideration below was the potential flood stage of a river, then odds are a simple plate girder deck bridge would be used.
Remember, any structure below the track is preferrable to a lot of structure above the track, as it adds to maintenance costs, reduces clearances, and is more expensive to build. Consider the following... The Western Maryland's Keystone Viaduct in southwest Pennsylvania.
The bridge was abandoned in 1975 or so, but you can still see how a single track was installed on a curve within the bridge... the reason for the box truss?
The line crosses over the B&O main at a narrow angle, which lengthens the necessary span, and also at a fairly close clearance, requiring minimal structure below the track. The same bridge also crosses a state highway and a creek, which were far less critical for clearance, so the curve is made up of several short plate girder deck spans.
The bridge is now part of the Allegheny Highlands Trail, built largely on the former WM rail bed. Photos 1 and 3 courtesy of the Western Maryland West Sub Website
My guess is for the short span you have there, you could do a simple girder plate bridge and have a very plausible scene.
Lee
Route of the Alpha Jets www.wmrywesternlines.net
Allegheny2-6-6-6 I have several of that exact same bridge on the existing part as well as for the planned future part of my new layout and I can say without hesitation that bridge does not work in the location where you have it shown in the picture. A prototype would never have a curve on a straight bridge. How would you support the track?, how would you work in the bridge abutment?
I have several of that exact same bridge on the existing part as well as for the planned future part of my new layout and I can say without hesitation that bridge does not work in the location where you have it shown in the picture. A prototype would never have a curve on a straight bridge. How would you support the track?, how would you work in the bridge abutment?
Say WHAT????
If I had a dime for every straight prototype bridge with a curved track on it, worldwide, I'd have enough small change to buy a locomotive - 1:1 scale. In fact, the only kind of bridge that can be built curved is a masonry arch. Even a wood trestle is a series of straight sections that meet at an angle at the bents.
The bridge abutments would be perfectly straightforward engineering (don't forget the bridge shoes!) As for supporting the track, the floor structure would be modified as necessary to get solid support under the rails - once again, perfectly straightforward engineering.
Actually, there were (in 2001) a series of bridges at the Indianapolis Union Station that, seen from the underside, appear very similar to an inverted through girder. Those bridges supported specialwork as well as plain jane tracks. I rather suspect they are still there.
My modeling plans include a number of deck girder bridges, single and in series. Almost every one of the tracks on those bridges will be curved - just like their prototype.
Beware of words like always and never. All it takes to blow the thesis is one contrary example. In this case, the contrary examples are legion.
Chuck (Modeling Central Japan in September, 1964 - including curved tracks across straight deck girders)
Ya beat me to it...
http://www.railpictures.net/viewphoto.php?id=298723&nseq=1070
Aralai, the bridge you're using will work just fine, but to make it look more realistic, some surgery may be needed. the track through the bridge should be replaced with bridge track that uses longer and more closely spaced ties, and the curve should be continuous. The stringers (or whatever you call the longitudinal beams under the track) should be located under the rails, and the trusses should be brought closer together.
Dave
Just be glad you don't have to press "2" for English.
http://www.youtube.com/watch?v=zQ_ALEdDUB8
http://www.youtube.com/watch?v=6hqFS1GZL4s
http://s73.photobucket.com/user/steemtrayn/media/MovingcoalontheDCM.mp4.html?sort=3&o=27
My main issue is the size of the truss bridge in the foreground taking away from the viaduct which will be behind it. I have another spot on my layout where I can install the truss bridge with a parallel double straight track, and now that I understand the prototypical reasons for installing that kind of bridge, can make it realistic by making clearance the reason for installing there - probably a road. Thanks for the advice!
I appreciate the photos - It makes things much more clear!
One other thought... large truss bridges are also employed to cross navigable waterways, again, to maximize span and clearance below...
Glad this has been helpful.
I read somewhere - I think in this MR PDF download - that you'd generally see through truss bridges being used for spans of 100' and longer
Here's a fairly low through truss on the former Pere Marquette, built across the Cass River in Bridgeport, MI. The river is not navigable at this point, but it does have a tendency to flood.
Picture is from www.historicbridges.org
Odave,
The PM bridge you posted appears to have a truss primarily to the low clearance based on the level of the grade, as well as the span. It looks like a fairly light structure, so it was probably cheaper to build than to add a pier in the middle of the creek for shorter girder spans. The flooding issue probably also played into the design, as flood waters can more easily pass through a truss bridge, where they might be likely to push a plate bridge off it's foundations.
This is what makes the Model Railway hobby interesting to me - learning about prototypical reasons for things like types of bridges etc.
Obviously I COULD make the truss bridge work in the place it is, and even justify it with some prototypical examples and reasoning, however as my main reason is to draw attention away from that track and more to the track behind, I think it will also be easy to justify the smaller bridge based on what you guys have told me. Realistically, with the river size I have, and that it is neither navigable, nor prone to flooding, the railway would probably not have built a truss bridge, and certainly not a double track one for a single track.
I look forward to learning more prototypical stuff - hopefully before I install things, although I have no problem making changes if it is a learning experience and makes things better....
Well, here's another thought... consider that most railroads are built along side of a stream, and in a lot of cases, competing railroads built their lines along opposite banks of the same stream... and you might think about the flow of your scenery a little differently.
It's easy to visualize a model stream emerging from the back drop and flowing toward the fascia board, but in reality, is that the norm? Obviously, tributary streams will come in perpendicular to the track, and flow into the river that the tracks are following. But when you have two parallel rights of way, what are the odds that they'd be stacked up the way you have them?
I faced a similar dilemma, as do most of us who like a little bit of meatballs (scenery) with our spaghetti (track)... So I reconfigured my river to follow the main tracks, and used bridges judiciously, again, following my prototype's practice... From left to right...starting up-stream.
The river "enters" the scene at this bridge, then flows to the right. Meanwhile, the track with the west bound B&O train bends to the left after the bridge, and follows the river along, the WM train in the next picture is headed eastbound from just to the right of the picture above. Note the industry in the background, on the left side of the river.
Further down stream you can see the double truss bridge in the distance. There is also track on the left side of the river, just off frame. You can see it a little better here...
That's the same plate girder bridge there on the left side. Below, the same line crosses under the truss bridge, then curves around to cross the river again. Now the track from the upper line is on one side of the river, and our original track is on the other.
I'm working now on an expansion plan that will extend the river around the peninsula, which will provide a backdrop for a longer valley, again accommodating the right of way along the stream bed.
Note that first segment of the river in the photos isn't shown, but it runs from roughly the big black arrow at "East Staging" to where the green river is shown just above that.
Anyway, I find it easier to think about the terrain as if it was there first, and the railroad had to work itself into the scene... Again, following the prototype!
Great information! Thanks!!!
Hope you don't mind... I took a few liberties with your plan...
By moving the river around a bit you can accomplish a few key things. First, the linear nature of the river will help camouflage the circular nature of the track plan. This will help maximize your illusion of distance.
Second, by running the river from the mountain on the left to the town on the right, you get a better feel that railroad is "going somewhere" too. You could even tinker with the idea of including some sort of port scene in conjunction with the town.
Here's an important one, you can now shift the smaller, less impressive bridge "down stream" to the right a bit, to get it out of the way of the larger more important steel trestle. It will also have a more realistic view, where it could be imagined that the low line is a competing railroad sharing the valley with the high line, or, perhaps the low line is the original alignment of the railroad, and the trestle represents a later "grade reduction project"...
Your double track truss bridge can be located over on the right side, where the river "escapes" to the sea beyond the benchwork, so you can utilize "existing assets".
Now, the best part... you have a wonderful stream bed to detail with rocks, trees, fishermen, what have you. I get the impression that you're looking forward to having fun with your scenery as much as you're looking forward to running trains. It will be a lot of fun to work "on the water."...
Let me know what you think?
Thanks Lee! I don't mind at all! It is a very good idea and I like it a lot. The only issue I have is that because of my original plan, the section where the river is planned now is a drop down from the benchwork on either side. I'm not sure that is really a show-stopper, since it seems like a river doesn't really require a huge valley, but I'm not sure how to deal with the valley which will have a fairly high viaduct, and then allow the river to flow to the right where the benchwork is higher...
...unless the flow of the river ran from right to left and there was a waterfall or rapids to account for the drop right after the small bridge... the only problem with that is that prototypically you would expect the river to originate in the mountains and flow out towards the town and a larger river, lake or sea.
I'm not sure what geography you're modeling, but it sounds pretty similar to the part of the world I'm working on... Appalachia.
I'm including Cumberland Maryland, where the Potomac River flows from west to east generally, but there are lots of ridges and oxbows, so at any given location it could be going in any given direction. Nearby is Wills Creek, which flows north to south, and just across the ridge is the Casselman River that flows toward the northwest, ultimately joining the Youghiougheny, Monongahela, and the Ohio at Pittsburgh. When you're in the mountains, the rivers don't follow a map... they follow the terrain!
I dig what you're saying about the change in elevation in the benchwork. I had to hide the same thing, that's what the waterfall next to the track here does...
Here's the same scene under construction...
You can see the 2" or so drop where the river bed has to fall to meet the lower level, otherwise the lower bridge wouldn't work unless it was a pontoon bridge!
Here's a look at a very early phase of construction, which shows the upper portion of the river.
You can see there's only 3/4" of separation between the railroad and the river surface. I hope this helps.
The good news is that while rivers have to run downhill, they don't have to follow the same kind of logic a road or a railway do...
Originally I was modeling Southern Ontario Canada, near where I live, and that's still the intention, although I have changed my mind from my layout being true to prototype to being more free-lanced. I have a feeling a lot of the scenery may tend to end up looking a little more New England, since I have a soft spot for New Hampshire, although we certainly do have valleys here that are a good size, as well as rivers and terrain like I am modeling.
I think I can make it work by reversing the flow of the river from right to left, and perhaps put a small waterfall or rapids to drop a bit near the top center, and then a larger waterfall as the river falls into the valley just to the left of the small bridge. That would not be unprecedented here, as there are many hard rock formations and falls over them.
You are correct that I am as excited (or more) to work on the scenery than actually operate the trains.
I appreciate your advice and hope I can tap on your experience as I build.
Aralai, Even after many years of doing scenery, I have learned quite a bit from Dave Frary and Joe Fugate.
Dave's latest book on scenery covers the gambit of all techniques, materials and will help to eliminate some of the common mistakes we will always encounter. http://www.mrscenery.com/Scenery_Book.html
I since find that Joe Fugates tutortorials fron the Siskiyou Line are linked to DVDs For some strange reason none of those links will Copy/paste.
Modeling B&O- Chessie Bob K. www.ssmrc.org
Thanks Bob - I just picked up that book!
Spent the weekend doing some reconfiguration based on the ideas from Lee about changing the river. Moved the Truss Bridge over to the new location behind the town, and started to carve the riverbed.
The Truss Bridge looks MUCH better over there, especially with a nice double straight track on it!
The river at that point looks like I could put a road down to a small boat loading ramp and/or dock - getting some scenery ideas!
I am going to have to perform some magic to make the river disappear to the left or right after it goes under the viaduct, with limited space, but I'm confident I can make it happen. There is more room to the right, so I may turn it that way, although I also had a thought of putting a break in the hidden staging at the back so the valley continues backward - so the train would be seen crossing the valley at the back. Will have to do some thinking about that.
Will try to take some pics and post tonight.
I know this is a bad edit job, but this is an idea for the valley continuing back:
Looking for some ideas for a potential bridge at the top left back - would span a valley or canyon:
http://cs.trains.com/trccs/forums/t/170242.aspx
There have been a couple of posts in the forums about bridges. I am planning on building a plate girder bridge wide enough to support a ballasted curved tracksimply because there isn't the vertical clearance to do anything else. In the research for this type of bridge I came across this web site and was amazed at the number of pictures of historic bridges and they show that just about anything is possible. This site also has a pretty neat search feature as well. Anyway, I pass it along.
http://www.historicbridges.org/index.htm
There's never time to do it right, but always time to do it over.....
Awesome site! Thanks for posting!