Large Scale Central

Concrete Bridge Build.

Track and Trestles
#1

Now that the turntable build is coming to a close and the triple dome tanker is riding the shelf waiting for soem good weather to take a spin I’m weighing options for a bridge. The section to be spanned is 33" long by 10" high. There is a double track going around a 10’ diameter curve. The tracks have been balanced on bricks and scrap wood. This section is also a step over point so I cannot go high. I was thinking about a curved trestle, then thoughts turned to 2 wooden bridges supported by bents at both ends and heavily in the middle. Surveying the site today made me think about building 2 culverts type bridges using plastic wood and scribing lines for rocks like I did for the engine bay foundation. I then thought of using concrete.

Doing a search here a old post mentioned a book by Jack Verducci “How to design and build your garden RR” which I own and Jack has a interesting approach to building forms out of styrofoam. Once the concrete was set he would pour a mixture of vermiculite and portalnd cement and while this setup he carved the stone face into it.

My thoughts: what if I built a form and while the mortar set carve my rock face in that?

What are your thoughts concerning building a bridge using concrete? Considering the cold snap that is back and the 18" of snow we might be getting Wednesday I could be weeks away from starting this.

Suggestions and ideas welcomed. Thanks.

#2

Todd, one caution. I built a concrete tunnel. Each spring, when the rains came, the ground would get soft and the tunnel would sink a bit. So each spring, after the rains stopped, I would have to lift the tunnel and place pieces of slate under it to shim it up. Eventually I removed the thing, because I like running my Shay, and that was always the first locomotive that wouldn’t fit under it when it sank. So, if you make something heavy, make sure it has a good footing (support) under it.

#3

Todd- A few years ago I built a large viaduct out of blue insulation foam instead of concrete because I live in the dreaded Northeast, just like you. The freeze/thaw cycle can cause things to move quite a bit. This winter has been horribly cold in Buffalo, and the ground has heaved all over my back yard. One end of my viaduct heaved a few inches and will need to be “re-planted” in the spring (if we ever see spring!). I couldn’t imagine trying to re-level it if it were made of concrete. You might want to consider the weight of concrete versus other materials. Just a thought.

-Kevin.

#4

I’ve built a lot of concrete on my RR; roadbed; switch & crossing pads and parts of a tunnel. I also live were winters can be tough and frost heave a problem. My roadbed and switch pads are no less than 5 inches thick and reinforced with rebar, and my tunnel portions have 5" reinforced foundations. The only structure that has given me any trouble is a bridge abutment that was anchored to a tree root - not a good idea!

#5

I built an arched bridge with blue foam. Last year the ants decided to make a home inside it and its been tunneled out real bad. From a distance it still looks nice, so its not on my “now” list to replace it, its on my “someday” list. Someday, when the ants have destroyed it I guess.

#6

Tod,

I don’t know what your situation is with freeze and permafrost and all that, heck I’m a California boy, we don’t do cold.

You might consider carved blue extruded foam with a concrete fill or even a screen framework and stucco covering that can be carved (while damp) to look like cut stone or rubble rock. The stucco will take all kinds of stains and paint washes so you can get most any look, sandstone, granit, basalt, etc.

I think there are several threads on here and the other place about using foam for bridges/tunnel portals. I have only used it for buildings, carves really easy with a soldering iron.

I built some stucco covered piers/abutments for my double bridge and they are pretty easy if you know anything about metal work and cement. If your interested in this method I can probably still find some picts.

Rick

#7

Tod

I remember a few years back someone had made a viaduct out of concrete with re-bar and it rusted and broke the viaduct.

richard

#8

I suppose if you want a bridge built of concrete, that is the way to go, just remember that there is a huge downside to it.

OTOH, if what you want is a model of a concrete bridge, then the blue or pink builders insulation foam,suitably shaped and painted with latex first is a better way. I mention a base coat of latex, because oil base paints and most rattle can paints will melt the foam. I learned that the hard way.

#9

You guys are sending me in a different direction and it does make sense. I have also heard about rebar rusting inside the concrete causing cracks and eventual failure. Marc Horovitz of Garden Railways had that problem I believe.

My plan is a double arched culvert/viaduct with 2 tracks on top.

Thanks for the ideas.
Todd

#10

Todd- Here’s my “concrete” viaduct- made from blue insulation foam-

Might give you some ideas?

-Kevin

#11

I made my viaduct from PT lumber, and PVC board.

http://www.largescalecentral.com/forums/topic/17057/search/view/page/1

#12

Very impresive structures Bob and Kevin. You guys convinced me to abandon the concrete plans and pursue alternatives.
Thanks.

#13

Todd Haskins said:

Very impresive structures Bob and Kevin. You guys convinced me to abandon the concrete plans and pursue alternatives.
Thanks.

I personally think that is a wise choice Todd!

#14

Bob McCown said:

I made my viaduct from PT lumber, and PVC board.

http://www.largescalecentral.com/forums/topic/17057/search/view/page/1

Reminds me …Where is the Dead Rooster Gulch story? I thought it was on that thread. That was funny with the town dignitaries

#15

dieseldude . said:

Todd- Here’s my “concrete” viaduct- made from blue insulation foam-

Might give you some ideas?

-Kevin

Don’t look like 10’ diameter curves to me Kevin!

#16

David Russell said:

dieseldude . said:

Todd- Here’s my “concrete” viaduct- made from blue insulation foam-

Might give you some ideas?

-Kevin

Don’t look like 10’ diameter curves to me Kevin!

Rooster-

It’s an old picture! They are 9’ but you can leave the sway bars in. The new curves will all be 20’ so the Amfleet will have no problems!

-Kevin.

#17

David Russell said:

Bob McCown said:

I made my viaduct from PT lumber, and PVC board.

http://www.largescalecentral.com/forums/topic/17057/search/view/page/1

Reminds me …Where is the Dead Rooster Gulch story? I thought it was on that thread. That was funny with the town dignitaries

That was on the “TrainOps” thread. In 2012 I believe

.

#18

You guys convinced me to dump the concrete idea and try the foam insulation approach. Well it is finally done and I am so happy with the way this bridge came out. Today I brought it out and put it in place where it will be going but it was too cold to be kneeling and digging in the dirt. Maybe next week.

The bridge is 16" wide to accomadate 2 curved tracks and is 32" long. I wanted a really flat rugged surface so I ended up gluing a piece of hardiboard on top. I put a small lip on the edges to keep ballast from falling off. The whole bridge was painted multiple times and detailed with 3 colours. I tried to match the stone around the bridge so it would look like it was built from them. I used a wood burning pen to cut in the mortar lines then roughed up the edges with a wire brush.

The tender on top is a sneek peek of my latest project.

I think the bridge will look alot better than the bricks that have been holding up the track.

#19

I think you got something there now Tod, that looks really nice.

Is that a date or a bridge number on the plaque stone?

#20

Ya done good, Todd!