Trestles

One of the nicest steel girder bridges I have seen in Z scale was Hien Nygen's. It is just an incredible bridge combination. Very tall, lacey and delicate in appearance. Below is the photo I took of it during the NTS in 2011.



Stony, I think you are off to a good start. The biggest change I would suggest is making the pieces less solid and with more relief. I-beams were often used. The addition of gusset plates on the connection angles would be a great detail. The photo Mark linked to shows cross beams with an intricate X pattern. If possible to recreate this look, it would really make the bridge supports more delicate and less massive.

Rob

Stony,
Can you do open web truss beams & box beams(see Plastruc catalog pg 10)? I'll be going the Greenville high bridge I linked to and can take some details & images. I thought about this after your 3D talk at NZSC, but couldn't think of a way to "grow" the trusses.
The truss construction is common in the west, so I think you can find a few takers.

Mark

BTW: maybe its time to move this discussion out of Jed's post.

ztrack wrote: One of the nicest steel girder bridges I have seen in Z scale was Hien Nygen's. It is just an incredible bridge combination. Very tall, lacey and delicate in appearance. Below is the photo I took of it during the NTS in 2011.

Stony, I think you are off to a good start. The biggest change I would suggest is making the pieces less solid and with more relief. I-beams were often used. The addition of gusset plates on the connection angles would be a great detail. The photo Mark linked to shows cross beams with an intricate X pattern. If possible to recreate this look, it would really make the bridge supports more delicate and less massive.

Rob

Not trying to throw water on the bonfire here, but I'm concerned about the possible warping of thin pieces like this. If it doesn't warp, then I'd say this is a feasible project. I agree, Stony is off to a good start.

And Rob, your picture doesn't even run a close second to the majesty of Hien's bridges, as they are truly wonderful to see first hand and up close.

OBTW, I'm not saying you aren't a good photographer, you did just fine, but I think you'll agree with me that one needs to get his nose within about 1 foot of this bridge to really appreciate the charm of this whole scene.

It's great to see new ideas, great pictures, great original work all in Z scale.

Go gang go.

Loren

I did a google search for steel trestles and viaducts and found some interesting sites.
It looks like most of these things, are rectangular and not square. Also dont forget the concrete feet, which could be made separately and used for other bridges.

Kelly,
Right you are. There some rules for the size and shape to keep the towers standing. The tower span should be at least 1/2 the span of the intermediate bridge. So, if we use 80ft for that bridge span, the tower span should be at least 40ft. Maximum tower height should be 4-5 times the span, about 150'. From this posts should be 2ft square. Also, the tower posts should be perpendicular in the span direction. Enough math for the day.
I think the footing should probably come separate: too many size and shape options.
Stony,
Looks good with the gussets added. If you're at minimum dimension on the main beams, what's the size in real world numbers?

Mark

Stony,
Here's my thoughts:


The height is based on what I see on prototypes (UP) around me and the thought that 55-60 ft allows for train over train over train. Also assumes 2ft tower posts are about as small as you can go.

Span is based on the approx. 90ft girder bridges available in Z.

9-10ft width should be determined by the inside dimension under the bridge. My deck girders are packed away so I don't have an exact number.

It would be really nice if you could fake an I (H) beam on diagonal braces. While most bridges use truss girders its really only the these braces that show using the 3ft rule. (BTW: I use the image at the link I posted because that image is just aboutt the 3ft rule in prototype).

Any thoughts anyone?

Mark

I really like the look with it thinner and the gussets added. The only question I have pertains to the decking. Would you design this to be used with MTL's plate bridges, or design decking to go on top?

Rob

Rob,
From a prototype standpoint, I don't think anyone would go to the expense of a thru-girder bridge on a trestle. My first thought would be the Traincat and Micron Art brass which should be about 9 1/2 ft. Measuring the MTL bridge, the deck is 9 1/2 ft. Using the MTL as a deck girder, you'd need to extend above the top stringer 5-6 ft to mount it. I like the thinner structure too, but I think the posts could be a bit larger to emphasize their size difference from the bracing.

stonysmith wrote: I have my associate elves trying to sneak into Talent, OR and get me measurements of the MTL bridge at this time?

What do you want for measurements? I've got the bridge and a scale right here. I just can't chat, 'cuse I'm on dial-up until Thursday. I can even give you numbers on a bashed MTL plate girder bridge, although I can't think of anything I haven't already posted.

I like the last image: the posts to bracing size difference looks right and you added the gussets at the cross points.

Mark

Stony,
That is real close. The three tiers of bracing is just for under the bridge. Typically only 2 levels on the span side. Other than that, the geometry matches my WP bridges and a number of examples in the MR books and issue DVDs for an E75 structure.

Do you think there might be a possibility to adding a texture the diagonals? Maybe an upper surface lip to look like an I-beam or an upper surface diamond pattern pattern?


Mark

Stony,
The MTL bridge deck width is 15.8mm. Built as a thru-girder, Outside plate-to-plate is 25.08mm thickness of the plate is 2mm minimum. Built as a deck girder that outside number 19.8mm.
My preference for the bridges are the Micron Art and Traincat. It's been a while, so I have to dig them out and that won't be until the weekend. The Traincat unit would be the defining intermediate span and the Micron (properly bashed) as the tower span. Maybe there is someone here who has ready access to these bridges?
I don't have an exact height I'm thinking 10 ft from the bottom horizonal brace to the bottom of the posts: about 4-5 ft for ground clearance and the rest for pier and wiggle room. From the bottom brace to the top brace 55 ft.
Finally, finish off the top with a beam over the top brace and the posts.

The cost at shapeways you have for this is REALLY good. Even with the setup charge, I can't buy the parts from plastruct to do it.

So, anyone else have inputs, or are you leaving it to us insomniacs?

Mark

You guys have gone this far, why not go whole hog and make the girder bridge itself? something you could slide or glue on code 40 or 55 rails, Don't forget guard rails.