# steel girder bridge



## shay06 (Apr 27, 2009)

Has anyone got any idea on how I can span a long gap in my railroad with a steel girder bridge?
I want it to look like a typical girder bridge with steel rivet.
I thought of using a "c" channel turned upside down and fasten line to the bottom of it. But how can I get it to look like a typical girder bridge. Any ideas?


----------



## GarryNCGRR (Jan 18, 2008)

I made this bridge using plexy and styrene.









is this kinda what you are looking for? How long a gap are you crossing...could use more than one section if longer than one bridge can handle. 


Garry NCGRR


----------



## shay06 (Apr 27, 2009)

Looks great, can you explain what plexy and styrene products are. 
I've had some difficulty in obtaining products to build models because G scale still isn't all that popular here. 
The gap is quite long approx.18 feet in length.


----------



## K.A.Simpson (Mar 6, 2008)

I use steel purlins or "c" steel. It is galvanised and the rail sits on the top. I span 18 ft and the purlins come in 20 ft lenghts. I used purlins all around my layout. I started to pop rivet joins but found it easier to use arc welding to tack it together then a spray pack of "cold galvenising" to prevent rust. Leave it to weather for 6 months and paint the colour you want. The width of the purlin is 4" which fits rail on top just nicely. The thickness or height is 2". 
It is easy using steel because it only needs supporting every 6 - 9 ft if you are not intending to stand on it. My lay out is all above ground, 5 ft at the highest point to give me a reasonable level to run into my shed where all my sidings are. I dont have to carry out trains and park them when finished. You can weld or bolt onto the sides to hide the steel and make what ever type of bridge you like. Hope this helps.


----------



## MasonsDad (Feb 7, 2008)

Man that looks Great, I am wondering what the width and hieght of it is though, I have been entertaining the idea of making on of steel for out layout at SAGRES


----------



## Dougald (Jan 2, 2008)

An 18 foot gap represents a 360 foot long prototype bridge. That is generally too long for a single span deck girder bridge which usually is used for spans of less than 100 feet. The bridge should be built as a 4 span deck girder bridge each span being equal in length though tthere may be reasons for making 5 spans or for making one span a little longer or shorter than the others. 

Garden Metal Models makes a beautiful deck girder bridge in 4 different lengths and while excellent in appearance, it is not inexpensive. Advice on building one from styrene and plexiglass has already been given.

If the bridge must span the full 18 feet in one shot, the prototype options for such a long 360 foot bridge would usually be one of the deck truss arrangements. Marty Cozad is the leader in this regard and if you check the archives, you will find many pictures of truss bridges he has built. Marty gave a primer on designing these big bridges and it too is in the MLS archives at http://www.phoenixcontact.com I used his ideas as inspiration for my own series of three truss brisdges to span a 24 foot gap - they are built of steel welded together and I have no doubt of their strength as I can walk and sit on them.











An article on how I built them is posted on the Ottawa Valley Garden Railroad Society webpage at http://ovgrs.editme.com/Bridge

Other kinds of bridges of course may be used in the prototype world for such big spans. Marty Cozad's famous MLS brisge is a steel arched bridge. In addition cantilevered bridges of various styles or suspension bridges may also be used.

Regards ... Doug


----------



## jimtyp (Jan 2, 2008)

The girder built by Garry (pic above) looks pretty darn good. Here is a post where he describes how he built some girder type bridges: 
 girder bridges  

Styrene is a white plastic kind of like PVC, Evergreen makes a good product. Plexy is a clear acrylic (plexiglass), available here in home improvement or hardware stores like Home Depot, Lowes, Ace. 

Other options to span a gap would include a trestle, wood bridge, steel bridge (like posted by Doug above): 
 bridge  
 bridge  
 wood bridge  
 trestle 

Doug mentioned Garden Metal Models, I'll second that if you decide to buy rather than build. 

If you decide to build and you want rivet detail, I use this:  Press  in conjuction with  Advancer  and  Dies However, I've also seen nice detail using sewing pin heads or even glue drops to simulate rivet heads.


----------



## wchasr (Jan 2, 2008)

I recently won an Ebay auction for a simple plate girder bridge from this place:

http://mainlinebridges.mybisi.com/

It was inexpensive and for the price had enoguh detail to count. Came painted black and the box it was shipped in was bullet proof. It was made from 20 guage cold rolled steeel welded together. No rivet detail but it is structural enoguh that I could probably walk on it. they ahve many other bridges and price structures depending on what you want and what you are willing to pay for. If you aren't willing to build it your self you amy be able to find a local sheet metal shop that might do it cheaply for you. Don;t forget your HVAC contractors locally too. If they ahev the equipment to form Galvanized ductwork then they can bend lighter gauge cold rolled steel. 


Many folks here have built presentable bridges from a variety of materials. Scrap wood & Plastics being the least expensive of the lot. There are several books available in the states on building presentable model bridges. What If ound when I designed the ones I built years ago (all gone now) was that the longest a deck plate or thru deck plate would be about a scale 32 inches long. There was also formuals to figure the hieght of the side plates as well. The best bet is to find a photo of the bridge you'd liek to replicate against somehting for scale and model appropriately. Don't scale it up too far or down too far and it will be believable. 

Good Luck!

Chas


----------



## davidarf (Jan 2, 2008)

Shay06

This was my take on spanning about 18 feet. The deck is aluminium plate and channels, and the superstructure is made from exterior grade PVC.











My latest bridge is shorter, but the basic idea could be used for a longer span by increasing the height of the arch. 











The Hellgate bridge uses a similar design concept.


----------



## Jerry Barnes (Jan 2, 2008)

Nice work David.


----------



## Bills (Feb 20, 2008)

Here is a simple one to make and costs about $15 
http://www.mylargescale.com/Community/Forums/tabid/56/forumid/9/postid/84360/view/topic/Default.aspx


----------



## cubythewater (Jan 14, 2008)

Nice shots of your bridges in Garden Railways, Doug!


----------

