Does anyone know of a complete kit for a double-wide truss bridge?
Unfortunately, I have been concentrating my search for suitable bridges to models a bit more complex to assemble than what you are looking for, so I don't have any quick recommendations for other
bridge models (or even know if others are out there, I've always had the impression that Atlas had about the closest to a line of pre-assembled bridges of any HO manufacturer).. But based on my
experience as both a model railroader and structural engineer, here are some ideas to consider:
You can always cut down the width of the river -- say from 27" to 18". And use four of the Atlas bridge models I referenced above (2 on each track = 18"). Add a bridge pier (Atlas makes one, as do
others) between the two spans. Hey, no one says you have to follow the Atlas plan exactly, right?
It seems you can use 27" of the bridge models referenced above to make the span (3 on each track = 27"). You don't necessarily have to use a double-track section for the center span. Railroads often
crossed rivers as a single-track bridge first, and then added a twin set of spans when traffic and finances increased enough to justify it. You don't need to use the same bridge for all three spans,
often there are different circumstances that require one span of a multi-span bridge to be different from the rest -- often navigation clearances would require something like a Warren Truss bridge
for the main span over the navigable part of the river that has boat traffic, and Deck Truss bridges for the other spans, which were usually a little more cost efficient, with the trade-off being
less clearance above the river. Or a Through Plate bridge might be used for the main span, because they can be erected more quickly than a truss bridge can.
There are plenty of scenarios -- every bridge has different factors that go into selecting what type of bridge is used for each span.
Mark
I am looking for supplies to model a train trestle. Does anybody know a company which produces a good real looking trestle that is adaptable so that as I change my setup I can reuse it?
Have you considered scratchbuilding? There is probably nothing simpler than a trestle to tackle as a first project.
Model Railroader has had numerous articles over the last 50 or more years. And your hobby shop will probably have a couple of project books. A trestle is particularly appropriate for an early
railroad, one in timber country, or when a long but low bridge crossing a swamp or wide valley is required. I have never seen a specific rule of thumb, but it seems that a trestle looks wrong if the
distance across the valley at the track level is less than twice the height of the tallest bent -- in other words, about a 45 degree slope down on each side.
The key is to make yourself a "jig" or template, using a 12" piece of 1x8 or wider shelving and wire nails or brads. Lay out the 6 post centerlines, spaced about 2 scale feet at the top and battered
(sloped) outward from the center line approximately 1 in 12 for the first pair, 1 in 6 for the second, and 1 in 4 for the outermost. Use scale 12" x 12" which is readily available in any scale. If
you do this, all the bents will have the same slope and top width. Of course the bottom width will increase with height.
A heavier piece is used across the "cap" or top of each of the "bents" or supports, perhaps 12" x 16" with the greater dimension vertical. A similar horizontal member called a "sill" is used at
intevals of 12 to 20 feet, and the posts of each "story" rest on one such sill and support the next higher one (or the cap, in the case of the top story). More stories were used in the earlier years
of railroading than in current practice.
The bottom cap can rest on individual round piles driven into the earth, on masonry or concrete piers, or even on the ground if it appears that erosion has piled up earth around the footings.
These bents are generally perpendicular to the track and spaced at intervals of ten to fifteen feet. Stringers run from one bent to the next, grouped in equal sets under each rail. (Three to four,
approximately 12"x16" each). The ties, generally longer and thicker than standard, rest on these stringers. The caps were sometimes sloped up toward the outside of a curve if a trestle was built on a
curve, or superelevation was built in by shimming the ties up off the stringers on the outside.
Diagonal bracing is used on each story of the bents (sometimes two stories together), forming an X when viewed along the track center line. It also is used to connect adjacent bents, running from the
upper cap of a given story of one bent to the lower sill of the next.
For variety, you can run a roadway or track under the trestle. In this case one or more bents may be omitted, requiring the span between the bents on either side to be increased. A wood truss or a
steel girder bridge may be supported on these two bents. Because they must support both the heavier bridge span and a greater length and weight of train, these bents are typically doubled -- two
identical bents as close together as possible.
Keep in mind that trestles were a cheap and quickly built solution and you won't go too far wrong.
Alex
I would like to weather an Atlas black truss bridge!! You know make it look rained/snowed on - old!! I have tried using chalks, however when I apply Testors Dull coat to seal it the chalk all but
disappears. BTW I am using good all American blackboard chalk!! I run it over some sand paper to powder it. I have applied the chalk using a small brush, a rag and my fingers (not all at the same
time). I haven't used the rust paint yet, my guess would be dry brushing!! I'd appreciate any suggestions.
If your bridge is already a dark gray or black color then your set to go, for any other color first spray the bridge with Floquil Grimey Black from a spray can, and allow to dry over night. The next
day take a can of Floquil Rail Brown and spray the bridge with a covering of Rail Brown make it dark in some areas and light in others so the old color shows through. Use short quick bursts and allow
to dry over night. Next day mist the structure with water from a spray bottle the water will act as a mask so the finial color woun't cover compleatly while its wet spray the bridge with a can of
Floquil Engine Black again using short bursts, when your about half way through mist the bridge with water again and finish painting, then allow to dry.
When its dry you should have areas that look like the paints has pealed away leaving exposed metal to rust beneath, now hit a few areas with a Grimy Black Weathering spray 1-part Reefer White to
5-parts Grimy Black and dry brush some rust streaks onto the structure using Rust, Roof Brown, Rail Brown and Orange, now you should have a nasty looking old worn out bridge ready for any scrap
heap.
booker1067
Another neat technique I've seen for weathering vertical steel surfaces (car sides, ship hulls, oil tanks, bridge girders) is to paint the surface with a good coat of paint. When it is thoroughly
dry, get a tube of burnt sienna oil paint, not acrylic, oil.
Dab very small spots and smears of the oil paint on the object to be weathered. Let the paint set for a while, the exact time requires some experimentation. Load up a fairly large soft brush with
turpentine and drag it down across the oil spots. It dissolves the oil paint and smears it down, softening the splotches and giving rusty streaks down the side of the object. With practice its highly
effective.
Dave H.
Chalks provide nice weathering but fade out when dullcoated, as you've already found out. I get around this by using powdered pigments and then overcoating with Lascaux Fixativ, a Swiss product
recommended by the local artist's supply store. There is very little fade out with this fixative. Polly scale flat finish lightly applied with an air-brush works faily well too.
Alternately, you may want to try this combination of weathering,
Paint the bridge a faded out black/dark grey color, apply a deep rust color (like freight car oxide) to deepen the color in the crevices and corners, thicken up the rust wash to lightly briush paint
in some rusty streaks below the raised details like rivets and panels. A light downward stroke that pulls the brush away from the surface at the end of the stroke works well for this. Light gray
streaks can be added as well to represent chalky paint or the effects of bird droppings. Then dry brush with a lighter color of grey to enhance the raised surfaces. As an option you can spray down on
the model with a dirt color to represent dust and dirt that has settled on the upward facing surfaces.
After the paint has dryed for a day or so spray it with dullcoat if you want and the job should be finished.
Peter B
I know it's not prototype, but I need to find both 9 3/4 and 11 radii curved bridge girders or bridges. Anyone know of a source ???
Protoptype curved trestles are made from "deck plate girder" units, and those are always straight, unless the trestle is made from timbers, in which case a curved trestle is possible.
The famous Keddie Wye (true name: Spanish Creek Trestle) is made from all straight DPG sections. Only the decking is curved.
Peter
If the deck girder was curved, the torque when a train went over would rip it from it's mountings....
Jeff Scarbrough