My Scratch Built Modern Signal Bridge With Picture

Because I see the forum is very busy this evening, I'll try again about my topic.

While I cannot give you exact dimensions, the height to the bottom of the bridge must be at least 23 ft. the signal heads are at least 2 ft tall each. The width and height of the cantilever section(where the heads are) has to be big enough for a person to work on them when necessary. hopefully, someone else may have actual dimensions available. 

This signal bridge was kit bashed from a couple of MTH (2) Track bridges.  Works pretty well.  There are (4) double head displays.   Track spacing is 4 1/4" center to center. 

Here's a drawing of a PRR standard signal bridge.  The height of the bottom of the bridge is 22 feet above the top of the rail.  The http://prr.railfan.net/ site has plans for PRR equipment and structures.

Jan

BLMA makes the bridge you want, but not in O scale of course.  HO, N, and Z are available.  BLMA has a reputation for producing accurate models.  A worst case scenario would be to purchase one of there models and scale off it for measurements.  A pricey alternative of course.

Jim

The BLMA model is one way to go but a set of drawings to print to scale is best.  I'm trying to do modern signal bridges too. 

I found your request interesting, so I researched it. I found what I expected.

Each railroad hires engineering services to design the structures.

Each railroad determines their specifications based on their needs.

Each State has design requirements when you get near highways or for grade crossings.

The signals and their specifications seem to standardized. The support structures have basic engineering standards that must be followed for structural integrity, but each installation seems (or needs) to be designed for that location.

You may have to borrow from BNSF or search for the railroad that you are modeling. There are multiple patents for walk-out cantilever trusses that you can access, but the vertical support seems to be unique for the application.

The height would be determined by the clearance needed for trains and the distance from which the signal would be visible. I can only find old plans. AAR.org has publications, but members only access.

Perhaps a phone call to the railroad or a railroad engineering firm would provide some general specifications.

Just guess, SD70 height to top of cab 15'-7.5" + 6" of rail compared to height in photo. Have a photo of it under the signal? That one looks like it is at least 30' to the bottom of the walk-out truss.

Have fun! I learned a lot. Thanks.

Thanks for everybody's replies. Last night I started working on my new modern signal bridge and the picture below is what I have so far. I printed the picture off the internet to get a good front view. The height to the bottom of the top part of the signal bridge where the trains clear the underneith is 7 Inches and a quarter making 7.25 inches. Which in real life would be 29 feet. So I've decided to make it so it clears my MTH double stack cars. I know it's not exctly the same looking, but I'm trying my best. So I'll keep you updated with more progress of this signal bridge I'm making with pictures.

I'm not looking for a modern signal bridge, but just a good working model of a bridge that would have been around in the 1950's.  Of course, anything built then could very well still be around on present day railroads.

The style of bridge that Plasticville/Bachman would be just fine, but I'd like it make a bit sturdier plus have operating lights or semaphore mechanisms.  I like the Custom Signals/Atlas type of signalling system, but I do need a few signal bridges for certain locations.

Paul Fischer

Here are a couple of pictures of a signal bridge I built spanning the passenger yard tracks inside of the train shed...

Alan

Very nice builds, gentlemen. There's a seller on eBay that makes inexpensive ($5 each roughly) signals in plastic. These are so cheap that you could buy them for their signal heads. They sell 3-over-3 signals with LEDs and a resistor on the common connection for 12-volt operation. Their called "We_Honest". I've bought some of their signals and like them.

Here's the progress of my signal bridge. Thanks Matt for the information, but I've already ordered some LED lights that will go with my signal bridge. So here's a picture I took today of what it looks like. I'm still not finished with the silver paint. The next picture I'll take is when I have the lights in. The bowl behind the signal bridge is to hold it up to get the picture.