# How Would You Build This Bridge?



## Suamico Pete (Jan 3, 2015)

I took this photo in September 2013 from my fishing boat on the Menominee River just south of Kingsford, MI. In my day I actually took a short excursion ride with my second grade class from Iron Mountain, MI to Wausaukee, WI on the old Chicago & Northwestern - right across this bridge. I would say 1955 or so.

If you were going to attempt to build an O scale replica of this bridge, what materials would you use? How would you fasten various structural components together? Given the actual height of this bridge above water, I can envision having to elevate the entire line of track about 17-18 inches above table top, as the elevation difference from the water to the bridge deck is about 70 feet.

Some might think this is a crazy idea, but I'll never know unless I ask.
Thanks


----------



## DaveInTheHat (Nov 13, 2011)

I'd start with a drawing the exact size that you need it. To support the weight of a train I'd use metal rods to support the track. The bridge structure would then be mostly decorative. The easiest way to build it would be plastic. A couple places have everything I see in the picture. Evergreen or Plastruct. Kit Kraft has trusses. http://www.kitkraft.biz/home.php?cat=20


----------



## sstlaure (Oct 12, 2010)

Looking at the height of the bridge vs the height of the engine (using the engine as a scale) it looks like the bridge is only 3-3.5 engine heights from the tops of the cement base to the bottom of the track surface. 

I bet to scale this would only be about 7" tall. If 70 ft is an accurate guess, then you're looking at 1:87 of that, or 9.6" (70ft*12in)/87

18" tall to scale would be ~130ft tall.

I'd build a nice sturdy deck (3/4" thick) that can just support all the weight going across then use plastic I-beams, etc. to make it look correct. Disguise the sturdy wooden deck with plastic plating.


----------



## Suamico Pete (Jan 3, 2015)

*Reply on How Would You Build this Bridge?*

Thanks to Dave and Scott for your help. Scott, I hadn't considered determining the height of the bridge from water level by comparing it to the engine height. Good thought. I had determined the height by referring to a USGS map which showed contour lines for elevations. I will do a similar determination as you have suggested. Obviously the greater the bridge height, the more dramatic the scene, but also greater the challenge of making a realistic layout away from the bridge itself.


----------



## Suamico Pete (Jan 3, 2015)

*2nd Reply - How Would You Build this Bridge*

Hello again Scott. I should have mentioned that I'm working in O scale. I looked up the dimensions of a real diesel engine of the type in the picture and they are about 15'4" tall. Using that as a starting point I scaled the height with an engineering rule and determined that the distance from the water surface in the picture to the track height is about 65 feet. So this is in good agreement with the info I got off of the USGS map.


----------



## sstlaure (Oct 12, 2010)

Oops....my bad - you said O scale above and I missed it.

O is 1:48 right? 65' would be 16.25" tall. Should look really nice.

The good news is with the larger scale you can make the deck material thicker and still be able to hide it within scale.

If it were me.....I'd probably look for a c-section in aluminum that would provide plenty of strength and still have flanges, etc. where it looks like a bridge. You could even glue in bracing under the deck (not that it would be needed.) Paint that sucker flat black and it would look fantastic.


----------



## Suamico Pete (Jan 3, 2015)

*Reply to How Would You Build this Bridge*

Thanks Scott - good idea. At this point it is only a dream for next winter season. My thought is that if I am going to build some type of elevated model railroad above a table top, it would be neat if it resembled a place my son-in-law and grand kids have seen with me.
Thanks


----------



## CTValleyRR (Jul 26, 2014)

What an interesting bridge! It appears to defy the basic laws of Bridge Building 101. I'm not a civil engineer, but I would like to see an analysis of the bridge members. Obviously, it works, because the thing is still standing 60 years later.

The reason I bring this up is that if you just assemble the pieces as you see them, your bridge may not stand. Use a good solid piece of metal for the deck, and attach the rest for aesthetics only.


----------



## sstlaure (Oct 12, 2010)

The hard part would be the middle point where the loading is trying to push both halves of the bridge together in the middle.

Load for the RH side of the bridge goes down the LH bottom leg to the base and vice versa for the LH half loading the RH bottom leg.

Small V in the middle of the bridge gives the bottom span sufficient vertical cross section to resist bending in the middle of the deck. Looks like the deck is of plated design like many standalone bridges. 

I bet there used to be a ton of river traffic requiring no center pylon in the river and they wanted high clearance without use of a draw-bridge.


----------



## Suamico Pete (Jan 3, 2015)

*Reply #4 to How Would You Build this Bridge*

To CTValleyRR and sstlaure: There has been a bridge across this stretch of river since at least 1938 (see attached aerial photo.) The bridge is so high because the railroad didn't want to make a deep cut for the right of way. The river winds through a narrow canyon with steep solid rock side-walls. In the photo looking to the upper center area you can see where there is a natural falls indicated by the white water. There is a dam there today and a beautiful backwater behind it.


----------



## DonR (Oct 18, 2012)

Pete

Will you have the 'table' size that would support the risers needed to get to
the to the scale level of the running rails on the bridge? You might need to use modeller's 'license' and reduce the height of the bridge to something that will be possible on
your layout.

Stop by a good hobby shop and you'll see actual I, T, L, U and other plastic beams
used in the bridge construction. It will be a very enjoyable project. Look
forward to seeing it become real.

Don


----------



## sstlaure (Oct 12, 2010)

Very cool.


----------



## Suamico Pete (Jan 3, 2015)

*Reply to DonR - How Would You Build this Bridge?*

That's a good question. My plan was to layout the track on the floor and see what options I have for getting the train to make a circuit. I could make a simple loop and have the train always run in the same direction or I could do some turn-around loops - one on each side of the bridge. I could then possibly hide a portion of one or both loops in tunnels. Lots to think about.

I appreciate the tip about hobby shops. I just started getting into this hobby this winter and I have picked a couple of nice pieces from antique stores and purchased a few maintenance items on line - but have resisted the hobby shops as my sales resistance is not the best!!

Thanks


----------



## sstlaure (Oct 12, 2010)

Just have the river below grade. Build your benchwork with a dropped section so you can just make the river bottom in it then make the walls of the river valley angle back up to the at-grade level with foam. You wouldn't need any grade in your track for this scene.


----------



## DonR (Oct 18, 2012)

There you are Pete

Scott has the right idea. Instead of worrying about risers and the like...keep the
train on the level and sink the river. You can then build the bridge to scale with
need for any 'license'.

Don


----------



## CTValleyRR (Jul 26, 2014)

I wasn't doubting the existence of the bridge, but rather noting that it is of unusual construction.


----------



## Suamico Pete (Jan 3, 2015)

*Further Reply- How Would You Build this Bridge?*

Thanks for the tip on lowering the river to below table top. I've thought about that, but only briefly. I have to build the portion of table that would contain this bridge feature and so that is definitely a possibility. It would be a tricky scene to depict either way, but lowering the river might make the whole concept a lot easier to build and maintain.

To CTValleyRR - I didn't take your comment as doubting the existence of the bridge. I went looking for the 1938 aerial photo because I was curious about the history of that stretch of railroad. The Univ. of Wisconsin has a website where all of the 1938 aerials are available for the whole state. With regard to the current use of the bridge, the Escanaba & Lake Superior train that I got pictures of crossed the bridge at about 5 miles an hour. I suspect that was so as not to shake the bridge too much. Train engineer has lots of guts!!

I very much appreciate all the ideas and comments that folks have been making. It adds a lot to having model railroading as a hobby.


----------



## traction fan (Oct 5, 2014)

*Bridge building*

Suamico Pete;

You have your choice of materials. The bridge girders could be scratch-built from styrene, or even wood. There are also some nice plastic girders available from Central Valley. Personally I would consider making at least a strong core for the main girders supporting the track, from brass. Then detailed outer plastic plates(Micro Engineering) could be glued on.
If you're really a bit crazy, the whole bridge could be soldered together using K&S brass shapes and Gold Medal Models "X"-Bracing. This would be a long, and expensive project, but would produce a beautiful, and strong* structure. 

* You mentioned grandchildren.

Traction Fan


----------



## broox (Apr 13, 2012)

My old man made this bridge out of scrap timber he had laying around (dismantled old pallets maybe?)

























He found a side on picture of a bridge he liked, blew it up on a photocopier to a huge size (multiple A3 sheets)
This is way out of scale though, should be heaps bigger for HO scale. You could see the rolling stock on the bridge in the original pic, and they were miniscule in comparison!

Can find some making of shots if you'd like.


----------



## broox (Apr 13, 2012)

I will add that it is pretty darn strong too! we have it suspended between 2 modules with less than half a centimetre of each end resting on the modules, and it supports the whole thing really well.


----------

