4 track bridge

[cacmage]

I've been working on an N scale around-the-room layout. I left a section open to avoid a duckunder, but I still need to get trains across.

I want to build a removable bridge. I've got 4 tracks to get from one side to the other, 2 on the main level, and 2 about 6" higher.

Has anyone tried building a double decked bridge? Does any one have suggestions on how to keep it steady and have the tracks line up exactly but still easy to get out of the way? I also haven't figured out how to wire it so I don't have to unplug it when I need move it.

 

[Matthyro]

I haven't seen a double decker like you need cacmage. That could be tricky to make removable. Is there any way you could make it fixed and duck under it. I have a two track bridge on my layout that is fixed and the duck under is easy because it is 56inches above the floor.
Welcome to the Gauge and hope someone can provide you with better ideas.

 

[cacmage]

Right now its about 48" off the floor. I could shave off an inch by not using foam, but I doubt that would make much difference. As a last resort I could make it fixed but not untill I've at least tried the removable route.

I'm not worried about making a realistic bridge, might not even ballast it. That's a ways off though, the track's just sitting on it right now.

 

[60103]

One of my friends built a 2-level gate into his HO layout. It's hinged at one end and cut at an angle at the other. We have had a few problems with alignment as the wood expands and contracts with the seasons. (and this is HO -- N might be worse.) The tracks aren't above each other but 4 or 5 inches apart.
I have an idea for wiring the bridge (I'm about to put in a single track liftout for mine) so that trains stop if it's been removed.

 

[scoobyloven]

cacmage

how long would it be

i have a t single track bridges on my layout and building a nother the longest one i hav would be 30 inches when it is done as for powering mine i use the hook up parts for a rc car the ones you see on that hooks the battery up and as for making the bridges i used old o scale track i found at a flea market. and as for lineing the track up i used a grove i cut into the bench work and ran a gide rail that would slide into it two gides on each side but you would want to build the bridge and put the track on it and use a pice of rolling stock (like a box car) and make sure you have it lined up and everything rolls free and with the bridge in place mark at each corner for a gide into your benck work( i used a holes in my bench work with pins at each coner that would go into them) then run your wires and temp hook them up ans run a full train over it to work out the bugs then when everything is how you want it put the rc car battery hook ups on the wires they are male and a female conector or use a you can use a copper plate under the bridge and one on the bench work.. i'll post some pics of what i have

 

[cacmage]

The gap I need to cross is about 3 feet, the bridge itself is 45 inches. I'll probably shorten it to make it easier to put in/out. The 2x4 base doesn't need much overhang to keep it sturdy.

The approach tracks are wired to toggle switches right now. Eventually, I'll put in a switch that will cut power when the bridge is out. Still not sure how I'll connect the bridge wiring yet. I'm leaning towards pins or plates as you mentioned.

 

[ezdays]

Ya know, Verne Niner has what I thought was a neat solution. His layout goes around the room and at the doorway he has a section of double track that swings down instead of up. He said he first built the swing-away section so it fit really tight, laid his tracks over it then cut the track once everything was in place and working. I've watched trains run over that section over and over without once having a problem, it lines up perfectly every time. I didn't ask, but I'm sure he has those sections of track wired to the mating tracks.

It could work for a bridge.

Don

 

[jdh]

i am using a "swing down" bridge for my around the room layout which is shoulder height from the floor.

this is a piece of 5ft long plywood with a stiffener [think T girder].

hinged on one end, swings down to the floor.

now two feet of this "swing down" runs UNDERNEATH the shelf layout then spans the gap, then attaches to the other side.

MMMMMMMMMM MMMM
--------------------bbbbbbbbbbbbbbbbbbbb-------

MMM = shelf layout

---- = swing down

bbbb = bridge upon the swing down.


the swing down is sceniced [minimal] to look like a river with a bridge over it.

i made the bridge and track removable so i can have different looking bridges on it. [bridge and track adhere via friction and gravity to the swing down].


another idea might be a "pull up".

you could use pulleys [or eye screws for that matter] to RAISE then multi level/track above and out of the way.

a pull up would eleminate the angle issues.

you could also just keep on with the insert method you are using now too.

 

[Mike R]

cacmage;
I don't know where you are located, and whether your layout room is subject to varying humidity between seasons, but most of us have to deal with that, even if our layouts are up on a ground floor.

No offense, but the lumber as shown in your photograph looks to be of a type that will expand and contract between seasons, and will twist and warp as it fully dries. This is not knowledge speaking, it is experience...I have had more than one moveable bridge....swinging, liftup, and swing-down, and all gave some degree of problem.So did the adjacent benchwork, even when built of kiln-dried #1 pine.

As stated before here, having two levels complicates things further.My advice would be to make the bridge out of an engineered material [like MDF or Particle board], rather than lumber. For the first couple of full years, just have it as a lift-out section, not a hinged one, to see if you get distortion or not.Make it as short as is feasible, 32" to 36" wide maximum.
For wiring, it depends on your control system, but automotive-type trailer plug connectors work fine for 4 wires at a time.
good luck & regards / Mike

 

[cacmage]

I'm in northwest Ohio. My layout is in a room I built in the basement. I hadn't been worrying about expansion/contraction much. Maybe I should. Is there as much of a problem with the foam or plaster expanding? The base has a little wiggle room, and I'm sure I could make the foam float on top of it.

I'm still not comfortable with the double decked bridge idea, I'll probably make 2 separate bridges a few inches apart, one higher than the other. I'll probably experiment with a swing up/down design too. I don't have enough room for a sideways swinging bridge, and I don't see the advantage of a pulley system over a lift out. (except maybe to store the bridge somewhere when it's out)

Electrically, I like the idea of a swing up/down. Wires with a little slack at the pivot point and I wouldn't have to worry about a connection there.

Thanks for all the ideas, I hope to work on it this weekend. I'll take a pic if I get something working.

 

[shaygetz]

Looks to me like you're off to a good start. One of the things you could do is, at the end of each track, both on the layout and on the bridge, solder the ends of the rails to screws driven into the wood under the track. Since you're not scenicing it (I wouldn't, just an added complication), I would wire up a multiplug harness, one for each lane of track. It would provide for continuity, avoiding the need for rail joiners in well laid track. I would wire the leads up to the gap in such a way that the last 18" or so would be electrically dead whenever the bridge was out ( don't want to see your best loco pulling a full string into oblivion ). Finally, I would add guard rails, much like you see on turnouts, on the bridge and on the leads approaching the bridge. Hope that helps some.