Large Scale Central

A Bridge Build for the Little River R R

Modeling
#1

I wanted to build some of the steel bridges constructed for the Little River RR in the early part of the 20th century. The Little River RR, a logging RR, ran in the mountains of East Tennessee connecting the mill in Townsend with the logging sites higher in the Smoky Mountains. It also moved tourists and passengers escaping the cities of Tennessee for the cool of the mountains.

I am trying to model a bit of this interesting RR in my back yard.

The Little River RR built several riveted double-intersection Warren deck truss bridges about 1906 - 1910 as the rail road followed the Little River gorge up in to the mountains. The riveted construction technique made for very strong bridges.

![](http://freightsheds.largescalecentral.com/users/grabnet/Bridge art 1 Long arm bridge.jpg)

![](http://freightsheds.largescalecentral.com/users/grabnet/Bridge art 2 Bridge with black iron.jpg)

![](http://freightsheds.largescalecentral.com/users/grabnet/Bridge art 3 Bridge with curve.jpg)

![](http://freightsheds.largescalecentral.com/users/grabnet/Bridge art 4 Upper deck of bridge.jpg)

I was quite fortunate to find an existing LRRR bridge on the very interesting web site http://bridgehunter.com This bridge built with the same technology as the Titanic in 1908 is still standing near Elkmont high in the Smokies.

![](http://freightsheds.largescalecentral.com/users/grabnet/Bridge art 5 Elkmont bridge.jpg)

![](http://freightsheds.largescalecentral.com/users/grabnet/Bridge art 6 Elkmont Bridge.jpg)

The pictures posted on bridgehunter.com included all kinds of angles and close ups that allowed measurements to be made for a 1:20.3 model of the bridge.

![](http://freightsheds.largescalecentral.com/users/grabnet/Bridge art 7 close up.jpg)

![](http://freightsheds.largescalecentral.com/users/grabnet/Bridge art 8 close up.jpg)

I had had a dialog with John LeForestier a while back about building Warren deck truss bridges. We had discussed possibly using aluminum angle with screws to build the interesting intersecting pieces of the bridge. After much thought I elected to use ABS and styrene plastic to build the bridge. I was particularly thrilled to find a Plastruct ABS product that allowed construction of fairly robust “t” girders using a web and flange that are glued using their specialty solvent for ABS plastic

To cross this part of the Little River, “Nelson’s Gap” I elected to build two spans of 40 scale feet.

I constructed a jig and began to assemble the pieces trying to follow the prototype pictures from bridgehunter.com

There is much more to come and I hope to continue with updates as progress slowly takes place.

Thanks for looking.

Doc Tom

#2

looks like you have good start on your project…hope all goes well for you…I too have a bridge I would like to model…The covered bridge in Wolcott, VT on the old Lamoille Valley line…not much left of the line any more say for the bridge

Good luck with your build and I will enjoy following it…Later All…Gerry

P.S. Nice bridges

#3

Neat idea, Tom. That’s a great prototype and you’re off to a good start.

I really like Plastruct products and I have downloaded their catalog so I can see what they have - they are a great place to get unique pieces as well as the standard shapes you have.

Will you be doing the stone piers, or sticking with what you already have?

For Plastruct, I’ve also had very good luck using acrylic cement in an applicator - it’s a great way to apply the glue.

(http://ecx.images-amazon.com/images/I/41kwPb6e4AL.SL500_AA300.jpg)

I first thought it was expensive at $12.65, but you get a whole pint which is a lot more than those tiny bottles! (that’s from TAP Plastics- http://www.tapplastics.com/product/repair_products/plastic_adhesives)

(You always do the neatest pictures!) :wink:

#4

Thanks Gerry and Bruce.

Neat idea on the glue and applicator Bruce.

I realized I forgot several pictures from yesterdays build session out in the shed.

Here is an overall shot of one completed side of the bridge. I think the Plastruct ABS will be strong enough to support my 1:20.3 Shay.

(http://i542.photobucket.com/albums/gg412/DrGrab/Bridge1_zpsd041bf20.jpg)

A close up

(http://i542.photobucket.com/albums/gg412/DrGrab/Bridge2_zps18ed0f33.jpg)

An extreme close up showing the “double” bracing.

(http://i542.photobucket.com/albums/gg412/DrGrab/Bridge3_zpsc0141e41.jpg)

Hopefully this is capturing the character of this prototype shot.

(http://freightsheds.largescalecentral.com/users/grabnet/Bridge art 7 close up.jpg)

I am not including rivets as I would be at this build for a year or more and I do have a RR to build.

Tom

#5

Bruce Chandler said:

Neat idea, Tom. That’s a great prototype

Will you be doing the stone piers, or sticking with what you already have?

Yes I will be doing piers and abutmennts. When it warms up enough I will make either concrete or stone abutments for the bridge at Nelson’s Gap. I also have to finish off the edges of the gorge too as right now they are very crude and rudimentary.

Thanks for the interest.

Tom

#6

I really like this bridge!!! Easy to scale up or down to whatever scale you are modeling too!

I may have to attempt something similar in aluminum…Thanks for the great pics!

#7

Tom,

Did you use a jig for the beams?

(http://i542.photobucket.com/albums/gg412/DrGrab/brdg10_zps343b53bd.jpg)

Or, are you just eyeballing it?

#8

Bruce Chandler said:

Tom,

Did you use a jig for the beams?

(http://i542.photobucket.com/albums/gg412/DrGrab/brdg10_zps343b53bd.jpg)

Or, are you just eyeballing it?

Hi Bruce,

Yes I used a jig to build up the “t” beams. There is such a nice fit between the web and flange that you could just eyeball it.

The “t” girders reminded me of the “t” beams on the bench-work of my old HO layout…they are very strong.

Tom

#9

Tom, nice start one the bridge…

#10

Tom,

Be wary of the ABS outdoors in hot weather. ABS does not have the structural abilities of the acrylics. ABS is one of the materials used in vacuum forming for those complex shapes in airplane models because of its flowing characteristics when heated.

What you have may well work, but just a note to keep an eye on it so if it starts to sag you can find a means to reinforce it before it becomes a real issue.

ABS can also be joined with MEK if you are working is a well ventilated area. I once, in a past career, built industrial models of chemical plants using what is now only known as Plastruct. MEK is what we used due to it’s fast setting time, as this is solvent bond in stead of an adhesion bond.

Great start on that bridge. Seems in the back of my memory I have seen that bridge in my explorations of the Smokey Mountains while living in Kodak. Will you be weathering it? And to what degree?

Bob C.

#11

More work on the steel bridge over the Little River.

With cold weather in Tennessee I went back to the shed with the trusty kerosene heater to work some more on the steel bridge over the Little River.

(http://i542.photobucket.com/albums/gg412/DrGrab/Bridge1-1_zps9843a1ac.jpg)

I completed the two side pieces of the first 40 foot span (1:20.3 scale ) of the bridge. These were carefully aligned and attached.

(http://i542.photobucket.com/albums/gg412/DrGrab/Bridge5_zpse9c9e45f.jpg)

Like the prototype picture the side pieces were secured using angle iron. Cross braces are to follow.

(http://i542.photobucket.com/albums/gg412/DrGrab/Bridge3-1_zps9008fbb1.jpg)

(http://i542.photobucket.com/albums/gg412/DrGrab/175476-L_zps089b47ed.jpg)

(http://i542.photobucket.com/albums/gg412/DrGrab/Bridge2-1_zps301cfc42.jpg)

(http://i542.photobucket.com/albums/gg412/DrGrab/175493-L_zpsc30958f6.jpg)

Please forgive the grainy pictures. My wife has the digital camera and these pictures were made using an iPad in low light.

Thanks for looking.

Dr Tom

#12

…(http://www.freethoughtnation.com/components/com_comment/joscomment/emoticons/funny/images/smile.png)…

#13

Nice work Tom! I think I have just the place for a bridge like that :slight_smile:

#14

Bob Cope said:

Tom,

Be wary of the ABS outdoors in hot weather. ABS does not have the structural abilities of the acrylics. ABS is one of the materials used in vacuum forming for those complex shapes in airplane models because of its flowing characteristics when heated.

What you have may well work, but just a note to keep an eye on it so if it starts to sag you can find a means to reinforce it before it becomes a real issue.

Great start on that bridge. Seems in the back of my memory I have seen that bridge in my explorations of the Smokey Mountains while living in Kodak. Will you be weathering it? And to what degree?

Bob C.

Bob,

I realized yesterday that I had not seen your post and questions. I apologize for that oversight.

I did not know that ABS might change shape with increased temperature. I will have to be very careful to observe that this summer.

In regards to weathering I planned on painting it black like the original bridge pictures appear to show it on the protoype. However with heat concerns maybe I should do a reflective silver???

Tom

#15

Really looking good Doc. That will definitely give you some nice photo opts

#16

Tom Grabenstein said:

However with heat concerns maybe I should do a reflective silver???

Tom

I don’t know if the silver paint will be enough. I’d do extra support pilings and secure the bridge to the pilings.

You might also try some plantings to shade the bridge, but that might spoil the view.

Ralph

#17

Thanks Ralph and Dave,

I read on the other site about ABS bridges custom built by another Tennesseean that withstood 100+F temps without sagging.

Fortunately this bridge will be a partial shaded site on the layout…not so much direct sun.

I am considering us composite board for the bridge piers and wondered about your collective experience with this material? Can it be covered and painted to look like concrete??

Thanx. Tom

#18

Looking good Tom. That will be a nice addition to the layout.

#19

Thank you all for the encouragement, it got me back outside in a chilly shed to cut and glue the interior cross members.

They are made from .25" styrene strip and cut in this jig to give 45 degree angled ends at various lengths. I used this on the angle iron pieces as well.

(http://i542.photobucket.com/albums/gg412/DrGrab/photo_zpsd0ca1764.jpg)

The interior braces are placed and glued.

(http://i542.photobucket.com/albums/gg412/DrGrab/photo_zpse71af6da.jpg)

To me this

(http://i542.photobucket.com/albums/gg412/DrGrab/photo_zps7956c670.jpg)

is beginning to look like this.

(http://i542.photobucket.com/albums/gg412/DrGrab/175476-L_zps089b47ed.jpg)

And hopefully like this before too long.

(http://i542.photobucket.com/albums/gg412/DrGrab/175530-L_zpscea1b6f6.jpg)

Thanks for looking.

Doc Tom

#20

Tom,

My note was more one of a ‘heads up’ rather than a full out warning. I am aware of the other ‘Volunteer’ that sells the bridges made of ABS. I also believe that the material he is using is considerably thicker (on the 1/8 to 1/4" range) than the material you are using. Quite possibly the trussed nature of your build will be sufficient to hold up, but then again …

As for temps, if memory is correct you are ‘on the plateau’ which sees a bit lower temps. Living in Kodak we several times in my tenure there saw temps right at or a bit over the century mark. The other consideration that many forget about is the solar heating from sunlight. East Tennessee has a relatively clear atmosphere, little smog, so solar heating is higher than other areas of the country. Consider how fast you can get a sunburn - that is solar heating. Another more direct example, I laid a piece of Aristo brass track outside on a late summer day. 85 degrees ambient temp turned into 145 degrees with the solar heating at the rail. Although I now live in the panhandle of Florida, that is still a good general reference of how much solar heat can be.

Silver would definitely be a better choice over black in my opinion … FWIW. Black would absolutely add to the heating effect of the sun, where the silver would likely reduce it. My intent was not to scare you into questioning you build, but rather to hopefully assist you in preserving a great build.

A thought just occurred to me. IF you have some acrylic available, you might cut a piece to fit on the inside of the truss if it starts to sag a bit in service. This would reinforce the structure and hopefully not detract from the overall appearance.

Bob C.