Hi Folks, I was looking for suggestions about a bridge I need to build. I have a door leading to my train room and I would like to put a draw bridge of some type across it. The area is about 38’’ wide and i was thinking about a bascule bridge because as it opens it would roll out of the way, But 38’’ seems wide for that kind of bridge (I model in HO scale). If that is to big of an opening for that kind of bridge anyone have any other suggestions? I most likely will have to scratch build this and Ive never done that before so I have alot to plan for. Joe A.
Realistically, that’s too big a span to cross with a drawbridge. This is something that needs more engineering “solidness” than good modelling, anyway. I would start with a good piece of kiln-dried, straight 2x4 lumber. On top of that, put 2 Atlas Chord bridges. Each bridge is 18 inches long, and they are relatively inexpensive. (Curiously, I can’t find them on Walthers.) Alternately, 4 Warren Truss bridges would fit the same space. Atlas makes (or made?) an extension called a “pony truss” that would add an additional 9-inch section on to the ends of these chord bridges.
First of all, this is low-cost, but nevertheless solid, solution. Remember, this needs to be totally removeable to get through the door, so it needs to be “forgiving” of the occasional bump, grind and fall to the floor. These relatively inexpensive bridges aren’t bullet-proof, but even if they shatter completely you’re only out a few dollars to replace the whole thing. Also, while they are OK as models, they just scream out, “Please paint and weather me!” It’s a great opportunity to practice some of those techniques.
Most important, these bridges provide inpenetrable side walls, so your trains will not end up on the floor if they derail crossing the bridge.
This is a particularly nice thread on a bridge that ran over the past week:
Thanks For the bridge thread. I figured I would start with a temp lift out section, but would like to fill that in later with something more automatic and realistic in the future. Looks like my span is about 233’ To long for a bascule but how about a lift bridge?
I’ve got a bascule bridge across a door opening that spans 18". How about 2 drawbridges facing each other. That would give you around 40" span. I also have a swing gate that spans a 38" gap with electical interlocks that kill the power 3" on each side of the gap
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I was just reading MODELRAILROAD BRIDGES & TRESTELS and saw a double bascule bridge. Each half could be 18’’ and that would give me 36’'. Thats close enough. A swing bridge would be great if it wouldent put the pivit right int the middle of the doorway. I was going to use a magnetic door lock on the room door so when the bridge is down the door could’nt be opened and a intercom for the kids to call the bridge operator for a opening.
Why not change the door to swing out instead of in, may not work in your situation but a thought.
I was thinking that a more “prototypical” solution would be to replace the intercom with a boat whistle, a nice deep one that sounds like a fog horn from across the bay.
The lift bridge that crosses the Cape Cod Canal is over five hundred feet long, but only raises to about 130 feet above mean high water - plenty long enough, but deficient in height unless your roadbed is less than fifteen inches below the height of the tallest person likely to use the passageway.
You might want to engineer MrBeasley’s suggested string of bridges as a bascule with the whole business rotating around a single pivot, either up (best - it protects the modeling better) or down. The pivot could be in the base 2x4 (I would use a 20 gauge steel stud instead of wood, but wood has issues in the desert that may not affect your layout space) about 8 inches out from the land end of the moveable section. The graphic below should give you the idea.
===|==================================|===== left end down, right end up.
FFF| ^pivot point |VFFFFF fixed frame, alignment pin fits in V.
I’ve included a similar design for a different purpose in the staging on my layout - gives me a track to fiddle open-top loads, which then disappears when not in use. Mine drops down, but the theory is the same.
Good luck
Chuck (modeling Central Japan in September, 1964)
Very intristing idea! I might be able to make something like that work. I could try to rotate the bridge like a gate also. Ill look into this idea more. Thanks Joe A.
This interesting indeed. After reading the replies a thought comes to mind about a double lift bridge though. If they are placed on each side of the doorway and drop down to the middle of the doorway, what would support the ends when they are in the down possition? Ken
Ken, I was wondering the same thing. I think misterbeasley’s idea might be the best. A nice strong bridge but with some kind of motor to rase and lower it. Anyone try this? Joe A.
Is this just a longish span along your layout someplace, or is it actually a functioning lift-out or swing up/down that you need for access generally? I just spanned across my 40" operating layout centre with a diagonal swing-down so that I can turn entire trains; it forms the centre of a reversing loop, essentially. What I did was use a span of 1.5" foam framed with two parallel 1X3’s below, running along the foam’s outer edge. It is glued and screwed for security. Most of this long span is built up and scenicked foam, but the bridge crosses a substantial shallow river. I had to use the Micro Engineering 160’ combination through and deck girder kit.
This foam span is hinged at one end to one side of the operating pit, and is secured by two barrel locks at the other side of the pit. Since it is so light, it is easily swung down to open up the area for quick movement. If you are interested, I will post a picture.
Sure I would love to see a picture. The span is across the doorway leading into the train room. This room is also the playroom so the door sees alot of traffic. I would like to be able to automate the opening and closing of this span. Unfortunatly this bridge connects my lower classification yard and engine terminal with the helix to the around the room layout. So it too is a very busy part of the layout action. Joe A.
Okay, here it is. I shot this hastily for your use…it is a work in progress, so I have not set up a decent shot of it. You should be able to get an idea of its construction. As you can see, it is not straight across, but diagonal so that I can keep the shape of a reversing loop with substantially wide curves. Two brass hinges are fastened just below the 1X6 facing you at the far side of the pit, and they attach onto ends of the wooden 1X3’s that you see below the blue foam. On the closest side to the viewer, there are two brass barrel locks. I will hook up a PSRev in series to the bus, then have it send feeders to the barrel locks. The half of the barrel locks on the span will have feeders running hidden behind the 1X3’s to the far hinges, and then up to the span rails. The layou halves of the hinges will have soldered feeders running to the tracks on that side of the loop. Should all work like a dream.
