Atlas Double Track Truss Bridge

John, center to center is 4.5"

Dan

Thanks Dan, is there a way to modify that?

Not easily, the tracks are a part of the bridge deck.

John, my normal distance is 4.75" center to center.  I just gradually brought them together as I approached the bridge.  No one notices.  Also, you need to have 10"+ of straight track on approach to the bridge or the longer, 18"+, passenger/freight cars may hit the bridge on approach as Andy L found out on his layout. The distance needed depends on the tightness of the curve.

Dan

I second that be very careful of any curve tracks leading to the bridge.  I had to move one of mine to prevent sideswiping.

Art

Thanks for the heads up... I did see quite a ways back a person that removed the deck and track and replaced with Gargraves? It actually looked pretty good. maybe I could squeeze a 1/4 per side. Reason I ask is I am in a tight real estate area where the tracks are spaced 4 inches from center to center apart.... I have 3 ft of straight track on the approach so I wanted to keep them parallel as well.

Art has a very good point about the approach to this bridge. This is an O63 and O54 approach.

silkcity can make any center you need on their bridge.

A half inch isn't very much.  I have trouble seeing the difference without measuring it when laying track.  I think it would be far simpler to do that than make a whole new bridge deck.  That is where the metal is that supports the span so you have to be careful in my opinion.

Art

problem is you can gun site the rails coming at you and it just does not look right...

Can you tighten the radius of the curve before the three foot straight approach to the bridge?

I  could but that put it below 081... I take another look at it tonight.

John,

What are you using for track?. I have three Atlas Pratt's and use Gargraves/Ross track. I removed the Atlas track rails and decking and replaced them with Gargraves that sit right on the girders. I can provide pictures and a how I did it.

CCN, by all means provide pictures and how you did it.  Perhaps you can start a "how to" thread on this and provide a link to the current thread and vice versa.  It's a "how to" that deserves a separate thread IMHO.

Okay guys, I have posted this a few times on the forum since I first did it in early 2007. This is an easy project and does not take a lot of time. It would be the same for the double and single track Atlas Pratt bridges.

The lower girder section, track bed and rails comes as a somewhat pre-assemble structure. What holds it together are screws and brackets that fasten the track bed to the girders. Removing all these screws and brackets will yield the seperation of the trackbed as a complete unit from the girder structure. Running thru the inside of each length of girder is a one piece steel rod which gives the bridge much of it's strength. The plastic girder is made up of sections of cross pieces (that attach to the upper structure) and lengthwise girder sections. With the trackbed removed, all these sections are no longer tied together and are free to slide about the steel flat strip that runs inside them. To gain back some rigidity, I decided to glue the sections together using the steel strip as the guy. Basically, I glued the face of each section to the next. I don't recall what type of glue I used but the bridge is made of "slippery plastic". I believe I used an epoxy of sorts. Once this was done, I then went and applied my track (Gargraves flex) to the top of the girder section. For each track of the bridge, there are two girders running lengthwise. I simply placed my track atop those girders. I decided not to permanently attach my track with glue of fasteners but rather used thin black diameter steel wire to hold it in place (see pics). I then complete the building of the bridge, gave it a coat of Dullcoat to cut the shine and put it in place. Setting the rail head height to match with the adjoining track may be needed. 

The spacing on my track centers is 4 1/4" and it can be adjusted some. Using Gargraves as I did, You can see in some photos how I adjusted the ties to hug the raised cross girder sections. I also added some guide rails from material I got from Ross Custom Switches (3' lengths). This aluminum rail has a slightly lower profile than the Gargraves rail and does not interfere with pick-up rollers. I also added some planking for walkways and bridge shoes. Hope this answer's your questions. If not, let me know.

Al - Very nice job on your bridges.  I didn't realize it was that easy to do.

Art