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Scratch Built Bridges

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Scratch Built Bridges
Posted by Forge_24 on Saturday, September 8, 2012 5:53 PM

Hi,

Just thought I'd post a few pictures of a pair of bridges I scratch built some time ago. Each rivet was put in by hand and they were made from strip styrene, enjoy.

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Forge_24, Ottawa, Canada

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  • From: Northeast OH
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Posted by NeO6874 on Monday, September 10, 2012 1:27 PM

Brilliant work! Bow

...and mostly because we like pictures here... Whistling

-Dan

Builder of Bowser steam! Railimages Site

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Posted by Train Modeler on Monday, September 10, 2012 1:40 PM

Who's the rivet mfg?

Richard

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Posted by Forge_24 on Monday, September 10, 2012 2:47 PM

I believe it is Tichy, but not positive, it has been a few years.

                                                          

Forge_24, Ottawa, Canada

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Posted by richhotrain on Tuesday, September 11, 2012 5:39 AM

NeO6874

Brilliant work! Bow

...and mostly because we like pictures here... Whistling

Photos are great, but how about some discussion on which parts you acquired and used to build the bridges and how you went about building the bridges.  Did you follow a set of plans or just work from photos of the prototype?

Rich

Alton Junction

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Posted by Forge_24 on Tuesday, September 11, 2012 6:00 AM

richhotrain

NeO6874

Brilliant work! Bow

...and mostly because we like pictures here... Whistling

Photos are great, but how about some discussion on which parts you acquired and used to build the bridges and how you went about building the bridges.  Did you follow a set of plans or just work from photos of the prototype?

Rich

I used Evergreen strip styrene strips and sheets for the actual bridge parts themselves. The rivets were made by Tichy I believe.

As for the design of the bridges, I followed images in the Kalmbach book Model Railroad Bridges and Tressles. I started with the smaller bridge as a test to see if I could work with the styrene and did the larger bridge second. These were my first experiments with scratchbuilding with styrene.

I worked on one side at a time, cutting pieces out, drilling holes for the rivets, inserting and cutting off the rivet backs, then fastening the parts together. All told, I think I built the pair of bridges over about a two week period of picking away at them. I still need to add some weathering to them both.

                                                          

Forge_24, Ottawa, Canada

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  • From: Dearborn Station
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Posted by richhotrain on Tuesday, September 11, 2012 2:58 PM

Forge_24

richhotrain

NeO6874

Brilliant work! Bow

...and mostly because we like pictures here... Whistling

Photos are great, but how about some discussion on which parts you acquired and used to build the bridges and how you went about building the bridges.  Did you follow a set of plans or just work from photos of the prototype?

Rich

I used Evergreen strip styrene strips and sheets for the actual bridge parts themselves. The rivets were made by Tichy I believe.

As for the design of the bridges, I followed images in the Kalmbach book Model Railroad Bridges and Tressles. I started with the smaller bridge as a test to see if I could work with the styrene and did the larger bridge second. These were my first experiments with scratchbuilding with styrene.

I worked on one side at a time, cutting pieces out, drilling holes for the rivets, inserting and cutting off the rivet backs, then fastening the parts together. All told, I think I built the pair of bridges over about a two week period of picking away at them. I still need to add some weathering to them both.

Well, let me tell you, you done good!

Thanks for that info. 

I have toyed with the idea of scratch building a lift bridge.  Your photos and description of the project are encouraging me to do it.

Rich

Alton Junction

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Posted by rdgk1se3019 on Tuesday, September 11, 2012 3:46 PM

Here is a bridge I built about 3 years ago........(1 out of 4)......that will go onto my layout.

I used 2 Micro-Engineering 30' girders and Evergreen styrene strips and shapes.

Dennis Blank Jr.

CEO,COO,CFO,CMO,Bossman,Slavedriver,Engineer,Trackforeman,Grunt. Birdsboro & Reading Railroad

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Posted by Forge_24 on Tuesday, September 11, 2012 5:32 PM

Nice bridge rdgk1se3019. Did it take you long to build?

                                                          

Forge_24, Ottawa, Canada

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Posted by rdgk1se3019 on Wednesday, September 12, 2012 6:28 PM

Thanks.

It took me about 2 weeks considering I had to go to 3 different hobby shops to get the right sizes of materials I needed.

And I did build 4 of the bridges at one time.

Dennis Blank Jr.

CEO,COO,CFO,CMO,Bossman,Slavedriver,Engineer,Trackforeman,Grunt. Birdsboro & Reading Railroad

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Posted by cv_acr on Friday, September 14, 2012 1:27 PM

Forge:

That's some really clean crafsmanship on the truss bridge bracing and rivets, but the deck of the bridge looks way too spindly to actually support the weight of a train over it, and there's absolutely no lengthwise beams to support the ties for the track.

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Posted by Forge_24 on Friday, September 14, 2012 1:41 PM

cv_acr

Forge:

That's some really clean crafsmanship on the truss bridge bracing and rivets, but the deck of the bridge looks way too spindly to actually support the weight of a train over it, and there's absolutely no lengthwise beams to support the ties for the track.

You are right and that has bothered me about them since I made them. Perhaps I will add some more supports.

                                                          

Forge_24, Ottawa, Canada

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Posted by doctorwayne on Friday, September 14, 2012 4:54 PM

While that's very nice workmanship, especially on the truss bridge, I have to agree with Chris about the design of the deck.  I also wonder about the truss layout and how it doesn't directly correspond to the arrangement of the cross members and braces of the bridge's top.  It seems that the more logical (and I'm guessing, as I"m no structural engineer) the stronger option would be to adjust the length of the truss panels to match those of the bracing on the top.  This would result in a three-panel Pratt truss, with the centre panel having diagonals running in both directions.  The design as it stands places the vertical forces within the side structure at points other than the intersections of the horizontal bridge members. 

Although it's not overly clear in the photo below, the truss structure (top, sides, and to some extent, the bottom, supports cross girders (floor beams) at the bottom of each vertical member.  These, in turn, support longitudinal girders (stringers) which provide support for the track.


If it would be of assistance, I can remove the bridge and take a photo of its underside.


Wayne

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Posted by Forge_24 on Friday, September 14, 2012 5:12 PM

doctorwayne

While that's very nice workmanship, especially on the truss bridge, I have to agree with Chris about the design of the deck.  I also wonder about the truss layout and how it doesn't directly correspond to the arrangement of the cross members and braces of the bridge's top.  It seems that the more logical (and I'm guessing, as I"m no structural engineer) the stronger option would be to adjust the length of the truss panels to match those of the bracing on the top.  This would result in a three-panel Pratt truss, with the centre panel having diagonals running in both directions.  The design as it stands places the vertical forces within the side structure at points other than the intersections of the horizontal bridge members. 

Although it's not overly clear in the photo below, the truss structure (top, sides, and to some extent, the bottom, supports cross girders (floor beams) at the bottom of each vertical member.  These, in turn, support longitudinal girders (stringers) which provide support for the track.


If it would be of assistance, I can remove the bridge and take a photo of its underside.


Wayne

That would be of assistance Wayne, please do.

                                                          

Forge_24, Ottawa, Canada

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Posted by doctorwayne on Friday, September 14, 2012 10:12 PM

Sorry, Forge, I took the photos almost immediately after you requested them, but photobucket appears to be having some difficulties, as I can't upload them.  I'll post them as soon as the issue is resolved.


Wayne

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Posted by doctorwayne on Saturday, September 15, 2012 11:30 AM

Well, photobucket seems to be working again, so here is a couple of views of the underside of the bridge:

Hope that helps to explain some of the details of the deck structure.



Wayne

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  • From: Gateway City
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Posted by yankee flyer on Saturday, September 15, 2012 3:45 PM

Hi Wayne

Unless you are a structural engineer I'm going to give you a "TEN" for a job well done.    Laugh  Even if you are, your model train is not going to fall in the creek. 

Give your self an atta-boy.

Lee

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Posted by richhotrain on Saturday, September 15, 2012 4:23 PM

Wayne,

Did you scratch build that bridge or is it a kit?

Either way, it looks great.

Rich

Alton Junction

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Posted by EmpireStateJR on Saturday, September 15, 2012 4:43 PM

Dr Wayne,

That is one fabulous looking bridge (and scene). Your modeling skills are excellent in so many facets of this hobby from rolling stock, locomotives, buildings and bridges. That is why I always click on your posts. Help I' think I'm becoming a groupie. Smile, Wink & Grin

John R

John R.

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Posted by richhotrain on Saturday, September 15, 2012 6:08 PM

EmpireStateJR

Dr Wayne,

That is one fabulous looking bridge (and scene). Your modeling skills are excellent in so many facets of this hobby from rolling stock, locomotives, buildings and bridges. That is why I always click on your posts. Help I' think I'm becoming a groupie. Smile, Wink & Grin

John R

I have said before that doctorwayne should be permanently banned from these forums.  He is too good for the rest of us.  He simply doesn't belong.   LaughLaughLaugh

Envious Rich

Alton Junction

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Posted by doctorwayne on Saturday, September 15, 2012 8:12 PM

EmbarrassedEmbarrassedEmbarrassed  Geez, guys! Smile, Wink & Grin  Thanks very much for your kind words.

However, the bridge isn't scratchbuilt.  The main span is a Central Valley kit - the only modification was to use .015" music wire for braces in place of thread.  The bottom ends simply sit free, placing no stress on the bridge like might be possible if thread was stretched too tightly.
The deck girder on the east end is an Atlas through girder bridge cut apart and re-assembled using Evergreen styrene strips as the "structural steel" bracing - the bracing is visible only if you were in a small boat or canoe, and about to drift out into Lake Erie. Laugh


At the west end, in order from the main truss span, is another re-built Atlas through girder, then an M.E. 50' and a 30' deck girder.  The track is a mix of M.E. bridge track and the ties from the CV bridge kit, with code 83 rail used for both the running- and guard rails.  The piers and abutments were cast in homemade sheet styrene moulds, using Durabond 90 patching plaster, the same material as used for the "water". 
Here's a shot taken at low tide:


Wayne

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  • From: Weymouth, Ma.
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Posted by bogp40 on Sunday, September 16, 2012 8:20 AM

If you do remove the bridge to work on the added tie support, look into adding the latteral upper support girders @ both upper ends. There is no bracing to stop any side movement of the trusses. They can be seen on Wayne's bridge. 

Modeling B&O- Chessie  Bob K.  www.ssmrc.org

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