How to place guard rails on bridge - the MRH Forum

how they should be placed on my 50's bridge?

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Hi Dee,  The s era bridge rails I recall seem to have been a bit closer to the running rails ( but not as close as turnout guard rails are) than that photo but it might just be local practice. You might be able to find some 50s era CN bridge photos and see if the guard rails are visible. ...DaveB

Short answer

HI Dee,

My short answer in that if your bridge/guard rails are between the running rails then

1. they should be far enough inboard of the running rails to trap the full width of a derailed wheel.
2. they should not be the that far away from the running rails that would allow the outside of the rail vehicle on the side were the derailed wheels are outside of the running rails to contact the side of the bridge structure. Any impact to the side of the bridge structure by a derailed might weaken the bridge enough to cause its structural failure and collapse. 

I just checked one of our local (Australian) standards - It gives the distance between the inside rail face of the running rail and the rail face of the guard rail as 380 mm or about 3 to 4 mm between the railheads for HO model track.

Do a quick check of the thickness on a couple of your model wheels. The gap should be wide enough to allow your model wheels to fall into the gap and become trapped between the running rails and the bridge guard rail, thus preventing the other side of the derailed vehicle from wiping out your bridge.

You are off to a great start with your bridge, keep up the good work,

Not to hijack this thread...

...but HOW or WHAT IS the best way to glue that guard rail, keeping proper spacing, and not ending up with a huge mess.  I have made several attempts gluing the guard rails and I ruined 6 pieces of that Micro Engineering flex track.  Although it's a great deal more expensive, I am thinking of just buying the sections of bridge track from Walthers, but then all my bridges would have to be straight.

Thanks for indulging me.  

Ken L

making bridge guard rail

An alternative to glue that might work better would be to spike down the middle rails, if what's underneath them can accept spikes.

For myself, I'd do the whole thing the fast-tracks way with soldered PCB ties every inch or so. I'd do all the soldering at the work bench to make a bridge-length section of track with 4 rails and spaced out PCB ties, then lay wooden ties on the bridge in between where the pcb ties will go and the rails and pcb ties on top. This would enable a really nice look with the bridge ties spaced together closer than the non-bridge ties or different-sized bridge ties if either of those are prototypical for your era.

I'd build the bridge track straight, and then 'flex' it when laying it down. 

You can get a 'straight track' fixture from fast tracks, but it's probably not that helpful, as their stock straight one won't have slots for the guard rails. So if you had the fixture, you could only solder 2 rails, then you'd have to solder the guard rails in between, which is going to be harder than working far side to near side. 

Guardrail

The purpose of the guardrail is to keep the wheels from running off the ends of the ties or getting into the structure.

Put a wheel set on the track with one flange on near the end of the tie.  The other flange is where the guardrail should go (or actually that's the furthest from the running rail, it can go closer).

With the ballasted deck bridge, the object is to keep the wheel from running off the edge of the ballasted deck, since that's wider than the ties, the guard rails can be further from the running rail.

Matt, Very informative. I was

Matt,

Very informative.

If you want to learn more, please visit our website bridge guardrails.

I was just winging it, and now I have a good idea.

My rails about 14 inches inward from the rail and the extended guard rails are only 25 feet beyond the edge of the bridge. None of it has been glued down and I have more code 55 rail.

I'm guessing the extended rail is that way because it is the average length of a freight car?

I have seen some prototypes with shorter extended guard rail, but are modern scenes.

Here I am again!...

Get ready to laugh at me. Why not use DAP Alex caulk to "glue" the guard rails in place? Since I used it to glue the track to the roadbed, both plastic, and there's no damage to PECO ties. Unless ME has some "other" plastic. Or whatever track is used. I've gotten used to using that caulk for several places. It may not be permanent, but does hold sufficiently. My track and roadbed have been in use long enough to assure me, so I have to assume that gluing guard rails would be no problem. The other thought from me is that as you know, I am not in favor of permanence. I like to be ready to change things or repair them or move them around. ?? I might add, using caulk is a lot less messy than any glue. Especially Gorilla. I find that stuff a little "iffy" when I use it. For one thing, you have to hold the items very steady for a long time before Gorilla sets. And IMHO this caulk is cheap enough to satisfy this old frugal 82 yr old getting to 83/around the corner.

That sounds like...

ME rail on PECO plastic ties. The caulk should work just fine. I know you probably still have some DAP Alex still around. Try it! And what I said about it would be ideal. If that don't look right, you will be able to pry it up and relay and re-caulk. With no damage to either the rail or the ties. And when you are finally sure everything is just right, you can leave it alone. The caulk will hold those rails for a long time.