Big highway bridges, not railroad ones

[Ed Kapuscinski]

A bunch of Plastruct I beams and some "for sale signs" yielded I83:

[aikorob]

http://01f2788.netsolhost.com/ModelTrainBridges/master.htm
these guys do rail and road

[daniel_leavitt2000]

Again with those pesky laws of physics!

I think you mean Peteski laws of physics.
Du-dum tis.

I'll see myself out.

[OldEastRR]

Oh, that Rouge River bridge looks pretty good. I'm looking for what would be a two-lane secondary road (like a state route) over a 8-9" gap about 2" deep of a river and banks (and a millpond and dam, maybe) . Something that looks like a 1920s-30s-built one in New England, crossing a river to feed directly into a town. It should look more substantial than a country road bridge, but not of massive, main route, heavy truck traffic construction. So having arch-supported short spans like the RRM is very close to these requirements. Seeing as it's going to be parallel to piers from an abandoned and removed RR bridge, it will help convey the feeling of time and place I want.
This is a great product I never knew about before. In the "old days", when we needed to check out what was available for our needs we'd just look through the Walthers, Atlas, ConCor, etc catalogs for possibilities. All that's changed there is the catalogs are now websites. But is there some master web listing of these "little" and new technology construction companies like RRM? I know they have websites, but how can you look for some company you don't know exists?

[nkalanaga]

9 inches is only 120 scale feet, not a long highway bridge at all.  Paul Mallery's "Bridge and Trestle Handbook" notes that a lot of concrete through arch bridges about that size were built in the 1920s, and that would be a very simple design.  Two arches, made from wood or plastic, steel beam or rod hangers to support the deck, and steel cross beams under the deck proper.  No trusswork, lattice girders, or other fancy stuff, just rods, beams, and two smooth concrete pieces.  Add a good abutment at both ends and it's done.

Plus, the minimal clearance under the bridge won't matter, as most of the bridge is above the road.

[pdx1955]

Also, during that same period there were a number of steel bridges on now secondary highways of the pony truss variety. These could be single spans, double spans, or used in a combination with concrete or wood trestle pier approaches. Here's an example I built following the US 10 overcrossing of the Teanaway River in Washington (just east of of Cle Elum) which parallels the NP. It's made of Rix railings and roadway sections with basswood trusses/beams with paper gusset plates. I estimated the dimensions from Google Maps/Streetview and made up my own drawings. In the first picture, the bridge is sitting on temp piers for the photo  and the second it is loosely placed on the small portable NP layout.

[chuck geiger]

Same as Ed mentioned, "for sale" sign and plastruct beams and railings.





Rix on HO layout




Lee taught me the fence trick on this one

[davefoxx]

I'm most proudest of this scratchbuilt highway bridge that I built earlier this year.  Unfortunately, after all of my hard work, it never got permanently installed, because I tore that portion of the layout down.  I kept the bridge, though.  It's all styrene sheet, strip, rod, and tube pieces, with the exception of the Rix girders, which gave me a cheat to model the prototype's concrete girders.  By using only the Rix girders, this saved me big bucks over buying the expensive Rix bridge kit.  I also have enough styrene to build many bridges.



DFF

[pnolan48]

I used a Baltimore truss style bridge for an elevated roadway through downtown: (let's see if this  Google+ address posts):

[pnolan48]

Here's a long highway bridge in Alaska, and fairly new:

[SecretWeapon]

The photo does not seem to show any sort of support where the Kato truss bridge ends and the concrete bridge begins. Is that in fact the case?

Its sitting on the scenery at the end. I made the cut for the bridge to fit right into it. I have plans to make a 10' long bridge just for all the cool trucks coming out.

[nkalanaga]

Peter:  We had a bridge very similar to that north of Grayson, KY, until the state replaced it a few years ago.  It was on a state highway (local road), basically a frontage road for I-64, and had a fairly sharp curve at the east end, going into Grayson's interchange business area.  Many of the younger locals didn't know that the road used to go to the right, not left, eastbound, across what is now the interstate, and into Grayson proper, as US 60.  That now leaves town to the west, rather than the north, leaving the old bridge looking out of place.  It was replaced with a plain concrete deck girder bridge, about half again as wide as the road itself, because the state got tired of people running into the sides.

I wonder if there was a standard design, and companies built them as kits?

[OldEastRR]

I notice that most of you scratchbuilt hiway bridges, I assume because no matter what length or type you needed you found nothing commercially available. I lucked out with the rogue River bridge, as it's perfect for my use. No worry about clearances underneath because its going over a non-navigable river.
That NP layout bridge looks a lot like a larger version on I-5 just north of Smokey Point, WA. In fact there are a number of such bridges -- thru truss, Rix railing sides -- on I-5 in the northwest. I/m wondering if the interstate planners didn't just use existing 2-lane US Route 99 bridges  (I-5 basically runs over the old 99 ROW for miles at a stretch) for one direction of travel. Especially since the bridges they're paired with are of much later designs.

[pdx1955]

I notice that most of you scratchbuilt hiway bridges, I assume because no matter what length or type you needed you found nothing commercially available. I lucked out with the rogue River bridge, as it's perfect for my use. No worry about clearances underneath because its going over a non-navigable river.
That NP layout bridge looks a lot like a larger version on I-5 just north of Smokey Point, WA. In fact there are a number of such bridges -- thru truss, Rix railing sides -- on I-5 in the northwest. I/m wondering if the interstate planners didn't just use existing 2-lane US Route 99 bridges  (I-5 basically runs over the old 99 ROW for miles at a stretch) for one direction of travel. Especially since the bridges they're paired with are of much later designs.

Railroad bridges tend to be too narrow unless you convert a double track one, but then they can be too tall unless you need a long span. Here on the SP, you can go a long way with wood trestles, deck girders, and short thru trusses. Highway bridges tend to be a bit unique in most cases especially if you are trying to match the local flavor. Color is also important - highway bridges tend to be a shade of green versus the black/silver of railroad bridges and different states use different shades. If this bridge that I made was for an Oregon placement, then I would have used a more vibrant green, for example. In WA and OR steel thru truss bridges are typically the Parker truss type (rounded top) versus the more rectangular RR types so to me, it always look wrong when someone uses a RR bridge straight for a highway bridge around here (for other parts of the country this might work better). WA prefers use of steel and thus has lots of through and pony style bridges on its system. On I-5, they repurposed the old highway as the northbound lanes - sometimes building matching steel bridges in the southbound direction, sometimes using more modern concrete and sometimes the old bridge is wide enough for four lanes.

The actual Rogue River bridge that the kit is modeled on has like 9-10' lanes...trucks have to go down the middle (assuming that they are not too heavy) and the bridges crosses the river on a heavy skew. It's a neat prototype and would fit well in many places. Single-span concrete deck arch versions of that bridge are dotted around the NW and CA.

Truss bridges are easy to make - my dad showed me how to do this with balsa when I was a kid. Make a drawing, tape it to a board, put wax paper on top then measure/assemble the sides with using stripwood (or styrene/brass if you prefer). Add gusset plates from paper or styrene. Add the cross-beams for the deck and for the truss (if through style) and finish up with adding diagonal roof/deck braces.

[pdx1955]

Peter:  We had a bridge very similar to that north of Grayson, KY, until the state replaced it a few years ago.  It was on a state highway (local road), basically a frontage road for I-64, and had a fairly sharp curve at the east end, going into Grayson's interchange business area.  Many of the younger locals didn't know that the road used to go to the right, not left, eastbound, across what is now the interstate, and into Grayson proper, as US 60.  That now leaves town to the west, rather than the north, leaving the old bridge looking out of place.  It was replaced with a plain concrete deck girder bridge, about half again as wide as the road itself, because the state got tired of people running into the sides.

I wonder if there was a standard design, and companies built them as kits?

Not sure about the kits, but many highway and local road departments have standard designs which can account for a lot of the same type of bridge in many places. Here in Oregon, the pony truss is typically used as an approach span paired with though truss spans on the state system. You'll find plenty of these on the county roads and even on Forest Service routes. I've seen a number with wood decks (many with lower sides than the one that I used) on some pretty empty local roadways out in eastern OR. Some (many?) of these were old state highway bridges that were moved to their current locations replacing older wooden bridges.