I’ve decided that a creek runs through it - a small, slow creek (or as they call it here, a “Run”)will now go through my layout for visual interest and scene separation, and I’m cuttin’ into the plywood. It’s a small, slow running, marshy-type creek, a low spot in the landscape about 30-40 HO scale feet wide and probably 10-15 scale feet deep or so. There are two parallel tracks that will go over it, mainline and branchline (recently spun off to a shortline) that switches off of the main just prior to the creek.
The question I have is how would a real railroad deal with this…would they build a short wood trestle to bridge the creek, or would they just go ahead and make a fill (with a culvert) for the short distance…which is more effective or preferred, and would there be a difference on how main vs. branch lines would be treated?..would they do a fill on one and a short trestle on the other, or just fill both? Is a trestle or a fill more expensive and time-consuming to build and/or maintain for the prototype?
I could go either way, fill or trestle, or have one of each. Just want to know which would be more prototypically plausible.
There is a prototype for everything and you would probably find both. Fill with a concrete culvert is much less expensive to maintain in the long run over a trestle. Over a small creek you may also find a steel girder bridge.
I’d say it may depend on the (virtualized) maximum flood volume of the creek - if it would get very heavy it could swamp a culvert if the culvert is not big enough (it could swamp a small bridge too, of course, but less likely). Around tri-state NY nowadays I’d say culverts are more common (easier to maintain in general - a number of them have steel bars/grating across the upstream entrance to a) catch big debris, so they can be readily cleaned out by maintainence crews, and b) help prevent teenages/homeless from using the culvert as an underpass/hangout. Most culverts around here are concrete…not as many of the corregated pipes very popular among modelers.
Prior to 1880, you could count on a trestle…or fill. After that time, steel bridges were put in place, especially to replace a substantial wooden trestle,…or fill. Generally, if it could be filled in at most a few days, it was done. The railroads hated to bridge, especially wooden trestles.
Thanks ~ Would love to have one, but a steel girder would probably be too wide.deep for the spot. The creek is only about 2 inches deep from the shore, and a micro-engineering deck girder is about 1/3/8 wide, and that’s not enough clearance i think for the occasions that water would rise. A through girder would probably be overkill for the spot, prototype-wise, yes? It’s really more of a marshy area with a small stream line rather than a fast-flowing river or bustling creek.
So you see why I’m thinking then of wood trestle vs. a fill with culvert.
Chutton, I would think that this creek doesn’t flood. There is marsh land nearby that handles water overflow before it floods. It’s a small pasture stream.
So Selector, a steel bridge would be built to replace a fill? Interesting. I would imagine that in the 1940s or 50s my railroad probably would have done something to replace or retrofit the crossing. Are fills prone to break down or maintain, or is a steel bridge a more permanent solution? I would think this would be a small, short span…probably a few days to fill, yes. I saw a short (in terms of depth) wood trestle bridge in Harpers Ferry that I was thinking of, CSX,…RRs still use wood trestles a fair amount for simple spans?
Aside from what the prototype does, what strikes your fancy??? You did not mention the kind of railroad you are modeling; is it a small short line or a big class 1 RR? ALso the scale.
Your question actually reminded me of my book about building the transcontental railroad. When they had to cross a valley or river, they used a trestle because it went up quick and cheap - the government paid them by the mile of track surveyed and laid. Later they came back and buried many trestles with fill because it was more reliable and could not burn down.
Following this logic, the small RR would probably use a trestle because of inital cost, and for modeling, it would look better because of the rustic look. The big RR would use a fill with culverts or a bridge because they could afford the inital investment. For a bridge, you might look at the Atlas truss bridge http://www.walthers.com/exec/productinfo/150-590 this is HO and code 83; they make similar bridges in code 100 and N scale.
On the North Valley Sub we have many small Trestles to cross small creeks. Maybe not as small as yours, but they are small enough. There also is a deck girder on the south Valley Sub that is very close to the top of the water.
I think fill would be more proto-typical, as, like every one else said, it is less expensive to maintain. But just south of Wausau there is a Town Called Stevens Point. Just west of Point there are a few long deck girder spans. The creeks are very small, but they have these longs spans. I’m pretty sure it’s because of flooding; a lot of water gets in the ditches along the ROW. So maybe you could put in a Deck Girder for the length of the creek/marsh. (The girder doen’t have to be very big. It could be just a couple of " I" Beams supporting a seck of conrete. As that’s what the Bridge is like by Point.)
A small wood ‘pile’ trestle with wood cribbing/abutment would be used in early construction. A ‘fill’ with some kind of culvert would be an ‘upgrade’. Wood structures need lots of maintenance and the pile legs are a place for debris to collect in flash floods. On the DM&E line East of me are a lot of fills with very nice cut stone culverts - they have been around for over 100 years and are still good.
A ‘ballasted’ deck bridge is the standard currently for replacement of many bridges. Last years flooding in SE Minnesota wiped out a lot of bridges on the DM&E. Even some steel bridges ‘floated’ off of their piers! It took about 2 months for the DM&E to replace all of the damaged line. 2 of the multi-span plate girder bridges(like the Atlas one) were destroyed. The existing piers/abutments were removed and new concrete ones were installed with a ballasted deck bridge built using prefab ‘panels’. Many of the smaller wood pile trestles got new concrete abutments or even were replaced with a steel girder to span the waterway so debris could not pile up against the structure.
That generally seems to be the practice around here, although a lot of smaller waterways (mostly drainage ditches, well below the level of fill that the line sits on) were bridged by cut stone culverts with 10’ or 15’ of fill atop that. For your situation, I’d suggest putting the track on some fill extending out from both banks, then a low pile trestle, topped with either heavy wood or steel I-beams to cross the actual water area. You could also use the situation to emphasise the difference between the two lines, with a more elaborate solution for the mainline track, and something a little less sophisticated for the branch. The pile trestle could work for either track, then build something else, either simpler or fancier, as required, for the other.
On my layout, I used a small concete arch bridge to span a drainage creek - from eye-level, both the bridge and the creek are almost invisible.
When the UP built the Lane cutoff west out of Omaha, they built a wooden trestle over the valleys, then filled it in and installed culverts. The roads went through big culverts/tunnels. then in the 1990’s the roads had to be widened so they opened them up and installed bridges.
So in this case the prototype order was a wood trestle, a dirt fill with culverts, then a steel bridge or trestle.
In my area (Tampa Bay) since the late 1980s CSX has been gradually replacing the small wooden trestles with small concrete bridges that are ballasted. At least one replacement bridge that I saw is about 25ft in length running over a small, nearly dried up grassy creek.
Whether the RRs liked them or not, you will see that they sure had a lot.
I would go with a trestle. For one thing, on marshy ground, a fill might get infiltrated with water and undermined. A short trestle might therefore be more plausible than a short fill. For a long distance, it would be worth installing the drains etc. to make a fill hold up. For a short distance, a pile trestle would solve it more easily; the driven piles work by friction.
On a model RR, a trestle is much more interesting. A fill just looks like a wall.
There still are lots of low, short pile trestles around. If you want to be more modern, perhaps you could use a concrete pile trestle.
No, sorry, I was artless in my response. What I meant was that you always had the choice of bridging or filling. Once filled, it was not sensible to empty it and then bridge it…unless it turned out that the filling solution was a mistake in the first place…engineering goof.
Or unless it was discovered that the fill (despite being in place for over 100 years) was encroaching on the habitat of some obscure waterfowl which had recently been placed on the endangered species list… [:-^]
You are modeling a marshy low wetland with a small-flow stream. Does it flood? If so, how fast do the floodwaters run?
Many years ago, there was an article in MR (Modeling a pony truss, IIRC) that explained that the railroad used a short truss bridge with low sides because the frequent floods would push a plate girder off its foundations.
There is also the thought that prestressed concrete deck sections were frequently installed when older short-span bridges needed replacing. The grouting process would make the entire bridge, floor and piers, into a monolithic structure very resistant to flood stresses. That type of structure is usually built with a ballasted deck and ordinary ties, even superelevated if on a curve.
My preference would be for a concrete panel bridge under the main track and a pony truss with open deck under the former branch now short line. But then again, I’m something of a bridge freak.
There was a spot just east of Banff, Alberta where a new plate girder bridge had been built over a small stream like the one you are describing. Next to it you could see some pilings still sticking out of the water where the old wood trestle had been. The local beavers had built their dam around these old pilings and I was thinking that they may have been the reason for the new bridge. CP may have thought it cheaper to build a new bridge than doing endless battles with the beavers. So you could have an old crossing (in ruins) next to your more modern crossing. It would let you have the best of both and make for an interesting conversation piece. The beavers must have loved the smell of creosote to have those pilings going up through there little living room… Don’t get any ideas Crandel
Hmmm… a short pony truss and a concrete bridge. I did think that my span was too tight from the deck to the water to have a deck girder bridge. While i fancy that there isn’t too much flooding from this creek, it seems tight.
I’ve got to take a look at Walthers and see what is available in short pony truss and short concrete bridges, and also options for the short pile trestle. I think Atlas makes a pony truss. I do like the idea of another truss on my layout - I already have a large through truss that’s now ready for painting- they certainly add interest.