A scratch built bridge for the Little River RR

[Grabnet]

I was able to get a little more work done on the bridge over the Little River. I am trying to recreate this style of bridge.

 

 

    
    After much thought I decided to paint the steel structure black as all the prototype pictures I could fine showed the steel members were black. I also decided to lightly weather the bridge as it was in the late 1920's about 20 years after it was constructed.

 

 

    I positioned the two 40 foot spans over Nelson's Gap on the Little River using a very temporary center pier and temporary attachments at both ends. I was thrilled It was strong enough to hold the first train over the chasm.

 

 

 

    I think this picture looks a little like the prototype one above.

 

    Next step as the weather warms is to build a concrete or concrete like pier similar to those above in the prototype. Ideas and comments are welcomed as the Little River RR advances a few more feet.

    Thanks for looking.
                Doc Tom

   Doc Tom and the Little River RR guys in East Tennessee.

[ttrigg]

Very nice construction pictures. Do you plan on duplicating the intermediate concrete bent?

[Grims]

thats great im jealous wish i could be out working on my R.R. but just got another 18 inches of snow

good work looks like the prototype

Ed

[Grabnet]

Hi Trigg,

Yes, I do plan on trying to replicate the concrete pier. The stacked bricks are only temporary.

I am trying to figure out how to get the shape they used on the prototype done correctly. So far what I have found online is mostly trapezoids. What the prototype LRRR appeared to use is more rectangular with triangles facing the current of the stream probably to avoid snags of debris in the river.

All ideas on how to do this are welcome.

Doc Tom

[ttrigg]

Quick thought, get a chunk of dense styrene foam. Carve out the shape (and texturing) you want. Make a two part plaster mold. Fill the mold with cement.  

[Grabnet]

Neat idea. I will put that in the noodle as something worth trying. I also wondered about "plastic lumber" as used in deck etc. construction.

Here is another picture of the choo choo on the steel bridge.

Tom

[ttrigg]

Couple years back I looked into “plastic wood” for a non-GR project. Everything I looked at then that was over half inch thick had hollow cores. The “bottom” and “inside edge” of the board were scuffed and grooved for ease in glue-up. Not too conducive for 4-sided exposure. The front edge and top of the “boards” were beautifully grained. Of course, that was a few years ago when the product was just being introduced to the market and things could have changed.

 

Alternate idea: build a wood form. 2 pieces of plywood, 4 strips of 1x3 with 45 degree bevel, placed at a slight angle wider at bottom than top.

 

What ever you do I will be interested in seeing. Motive: Moving my GRR from ground level to elevated site, and the DG fill is a bit more expensive than I had anticipated. I have plans for something like you are doing, so would be in the market for successful constructions.

 

 

[Grims]

maybe theres somthing more complicated to this than im seeing but why not just make a wood mold wire it pour concrete and while the concretes green you can scribe blocks or what ever and once cured a little weathering or leave it to weather it self

just my thought but maybe im missing somthing

Ed

[Grabnet]

Thanks Ed and Trigg.

I appreciate your ideas and input.

That great modeling tool "Google images" had a nice picture of the shape these piers were constructed as. It is called "a sharp nosed" pier. Here is the view looking down on it.

Some type of wood or foam mold with the angled pieces may be the way to go.

Tom

[Grabnet]

Mr "Dandy" Dan, chief design engineer of the Tennessee Bridge Co., from over in Nashville, can talk for hours to anyone who will listen on the benefits of deck truss bridge construction.

 

 

Boss Crumb and Col. Townsend try to feign interest as the concrete cures on the new bridge pier for the steel bridge.

 

 

The crew of #2147 are just glad the bridge remains perpendicular to the Little River below and they are dry.

 

 

 

Here's the "back story":

 

After much thought I elected to go with a trapezoid shaped concrete pier. I got the dimensions from the internet and built up a form using foam board secured with Titebond III glue and sheet rock screws.

 

 

Rapid set concrete mix from Lowes was mixed with water and poured in to the mold after trying to get it as plumb and level and attached to the rocks on the river's edge.

 

 

 

The foam mold was removed and the pier remained standing.

 

 

After a bit of time the bridge was reinstalled and "Dandy Dan" could resume his exposition on bridge building.

 

 

Doc Tom

 

 

[ttrigg]

Like It. well done.

[Grims]

was the porous look intentional or was it air trapped in the mold?  im just worried if its air it makes an awful weak spot.

but looks good great job

Ed

[Grabnet]

Hi Ed,

Thank you for being so observant!!! No, it was not intentional. The spot is probably from not fully mixed concrete. I was thinking about applying a concrete patch but the patch kit at $7.95 was more than the $3.50 bag of cement mix used in the project.

There is reinforcing metal inside and hopefully the pier will not collapse.

My wife said "grow some plants there" to hide the blemish. Probably a good idea.

Thanks for looking .

Tom

[Grims]

actually the blemish look kinda good looks old like its been there a while but in the future when you do something narrower at the top than the bottom take a rod of some sort drive it down through the mold at different angles to get the air pockets out or quickly tap the side of the mold .

  with  steel rods supporting it it should be fine and like i said looks great

Ed

[ttrigg]

Cautionary statement:

Some brands of the “quick setting” types of cement when cured have a tendency to wick moisture to the inside. Wicking moisture has been known cause rebar to rust faster than normal. As the rebar rusts it can cause pressure on the inside of the pier causing it to “explode” (in super slow motion.) Several years back I had a pier start showing cracks after about 3 years. Six months later large chunks fell off exposing the rebar. Unless you can find the words “water proof” on the bag of ready mix you used I would suggest you apply some water proofing after the pier is completely cured, (about this time next year.)

 

Check the back issues of GR “If I had Known” about 3 years back, where the topic was discussed. In my case the replacement pier without any metal reinforcement is still standing well after about 7 years.

[Grabnet]

Thanks for the "heads up".

I had wondered if the pier could be cast with NO reinforcing metal. May have to try that on the next pier for the next bridge build.

Tom

[TJ Lee]

Great looking bridge!

Thanks for posting the pictures.

Best,

TJ

[monsterbigmike]

wow look great

[Grabnet]

Hi M.B. Mike,

Glad you liked the pics. Here is a short video with the bridge in "action."  http://youtu.be/GaKrABJn0VI

I couldn't get it placed in the video section here........no CAPTCHA codes for several days.

Hope you like it.      Tom

[Grims]

great video thanks for posting it

Ed

[Great Western]

Lovely video Tom, I enjoyed watching it.

I love those Shay type locos although I don't have one.  My awkward old hands would soon make it a regular 2-8--8-2 or  some such notation.