Question on material for ATSF LA River Bridge

[Yannis]

Hi everyone,

I don't know if this is the right sub-forum to ask, but since it is going to be a sort-of scratchbuild bridge, it might be.

I want to build the ATSF Los Angeles river bridge as it used to stand near the Elysian park in 1969. The bridge no longer exists, it got replaced by a more modern construction. My main concern is the three skewed Truss Bridge spans.

To cut a long story short, there is no kit that would approach it's construction, so i ll need to kitbash/scratchbuild most of it.

For the deck and core components that will bear loads i ll design everything and 3d print it. But i ll need to dress the core with styrene piece that accurately reflect the girders and the lacing pattern they had (Z pattern and gusseted depending on the part of the bridge). For that i think i ll need to obtain a few kits or pieces-sets from Central Valley, or re-purpose pieces from the Micro-Engineering Steel Viaduct kit that i got leftover.

Since i am not familiar with Central Valley kits... do you reckon they ll do the job? I had my eyes on the 1902 bridge kit and the following extra pieces:
https://www.walthers.com/gusseted-bridge-girders-kit-5-7-8-14-9cm-long-pkg-10
https://www.walthers.com/classic-laced-bridge-girders-kit-5-7-8-14-9cm-long-pkg-10

I ll need to build 3 spans roughly 3' 2" each in length.

Looking forward to hearing from you on this and thanks in advance for your time and replies.
All the best
Yannis

[jbvb]

Checking photos in a Santa Fe Pasadena Subdivision page on Flickr, I see there was one short span and two longer spans. One long span and the short span are pin-connected, using eyebars for members under tension only.  The westerly (towards LAUPT IIRC, I only crossed it a couple of times) span appears to be the same length as the longer pin-connected span, but it's plate-connected. Was the LA River's concrete trough widened at some time after about 1900-10?  Or did one span get wrecked by a flood? AFAIK that's the period when calculus got good enough to allow design of fully plate-connected bridges.

If I ever saw a more-skewed bridge, I don't remember it.  The lattice crossbracing on each end of the pin-connected spans appears identical, and the pin-connected spans will be where you use the Classic Laced Bridge Girders, the plate-connected span uses Gusseted Bridge Girders.  But I can't say how the scaled size of each will compare with the look of the prototype.  A 270 foot long through truss is pretty big. The CV bridge is 153 scale feet long, so its parts might look a little light and the portals a little low in a model of a much longer prototype.

[Yannis]

James many thanks for the reply!

It is actually three truss bridges plus 2-3 plate girder ones making up the whole "bridge". So if a kit was suitable i would be needing 3 of them (or 1 plus extra add-on pieces to basically use the kit as a donor for girder parts).

The bridge got rebuilt at some point after a flood in 1939 if i am not mistaken.

[Yannis]

Hello everyone,

Back on this with a twist after done some more research on the particular bridge.

The actual bridge had two Baltimore-style truss spans (150' each) plus one more similar truss span (100') complemented by two plate girder spans on the west side and one more on the east side (truss spans at the center).

The west plate girder spans were at a curve leading into the truss spans (that were skewed), the east plate girder span was actually over the SP/UP tracks that were parallel to the river bank.

So something like: plate/plate/truss-150'/truss-150'/truss-100'/plate.

Unfortunately i do not have the space to accurately capture the full length of it so i am considering 2 options.

1. Compress the truss spans from 150' to 115' and from 100' to 70-75' respectively, but only in length. Height and width will remain unchanged. Compress as needed the plate girders. This will practically mean that i will change the angles of the diagonals on the triangles forming up the bridge.

2. Leave the 3x truss spans uncompressed, but eliminate the east plate girder span over the UP/SP tracks, and have the shorter 100' truss span covering that instead. Compress if/as needed the west-side plate girder spans.

The prototype in question is this (link provided for discussion purposes)
https://www.railpictures.net/photo/854514/

and this is a snapshot of the scene from my trackplan. The SP/UP tracks I mentioned are the ones with a beige roadbed around them.


Looking forward to your input
thanks in advance for your time and replies!
Yannis

[Jerry]

I think you have a good plan there.

Whatever you do building that will be an impressive bridge.

Jerry