Small Wooden Bridge – A One-Night Project

By Shawn Branstetter, photos by the author.
Beginner Series

Most prototype railroads at one point or another have a need for a small culvert or bridge to cross a creek or drainage of some sort. Modeling these structures can be a welcome break from our larger projects that might have a tendency to overwhelm us and sit on a shelf for what seems like forever. Also, this can be a great scratch building project for a beginner.

To begin, start with your plans and bill of materials close at hand. All of my lumber was cut to size with my Northwest Short Line Chopper and then sanded square.

Once all the wood is cut to length I use my razor saw and an X-Acto knife to add texture to my lumber. Now I want my bridge to have been in service for many years but still in working condition. With that, my weathering will be heavy. Really take care and pay attention to prototype wood, especially ties. Notice how the elements really punish the wood even if it is well maintained.

Once you have the desired amount of texture, sand the wood with a fine sandpaper to remove any fuzz from the material. I really like to take as much care as possible to make sure my wood is as clean as I can get it. This will result in a more presentable model and photograph well.

As I have stated in previous articles, my materials for weathering wood is India Ink, watercolors (burnt sienna and black), water and dirt. I use an aluminum container filled with just a little bit of water then add the India Ink (the amount of black ink is dependent on the level of weathering you want to achieve). The water colors I sometimes place on a plastic plate that I can add to areas of the model as needed.

I brush on the water/ink mix and allow it to dry. Once dry, spots of fuzz that was missed in the initial sanding process is sanded off and I then continue adding coats of my dye mix allowing each coat to dry before the next one is added. This will tell me just how dark my wood is getting.

I do like to create sub-assemblies whenever possible. For me, it makes my projects a little more easy to handle. As you can see from the picture above, I have begun gluing the stringers together with small pieces of scrap wood I had in my junk drawer.

Now comes the fun part. As my final coat of wash is still wet, I brush on real dirt to my wood. I also use my finger in some spots to really smash the dirt into the grain and add more texture to the model. This will dry and then the access and larger pieces of dirt will be brushed off and sealed with a clear flat finish.

The dirt will also tie the colors together and add visual interest to your model. The results so far have been very realistic as you can see in the photo above (the ties are just placed on for the photo).

Now that the major pieces are almost complete, we can start adding our details. I am using Grantline nut-bolt-washer castings which were painted roof brown before being cut off the tree.

I created a very rough drilling jig for my stringers by cutting 3 pieces of .40 styrene strips I made and measured the holes. Now I have a right (side one) and a left (side two) handed drilling jig.

I add my NBW castings and again add a light wash of India Ink followed by a dusting of dirt. This will add additional contrast to your raised details and the dirt will tie it all together.

Assembly

Most projects you will want to create a jig and place your ties into before gluing. This will insure all ties are perfectly spaces and aligned, however, since my little bridge has been in service form many years, I don't want my ties to be perfect. I glued the ties down one-by-one but I did make sure the first tie was as square as I could get it. As I added the rest, I used a spacer, removed it just before my glue had set which moved the tie just enough.

Now that my ties are all set in place, the guard timbers are next.

I only added one coat of India Ink wash before I glued them to the ties. I am doing these a little different as I am going to add a heavier wash to simulate bits and pieces of debris that the train might pick up and hit the timbers.

So I add the guard timbers to the model and add my NBW details.

Once added, I begin washing the die onto the timbers. Don't worry about the ink getting onto the ties. Ties can fade slower in corners and the contrast will give your model a very realistic weathering effect.

You can use your X-Acto blade to add additional chips and scratches to your timbers if you desire.

And there you have it. Now all you have to do is add the rail.

I hope you enjoyed my little project and I hope it gives you some ideas to add small details like this little bridge to your layout.  I have provided plans for the bridge if you would like to try the project for yourself and if you do, I would enjoy seeing your results.

About the Author

Shawn Branstetter's picture
I am a graphic designer and founder of Shortline Modelers Lounge. I love California shortlines of all types, especially logging.

Comments

eTraxx's picture

Excellent Shawn. I have just such a need for my On18 branch and will be making one of these .. soon as I can get caught up from other projects!

Shawn Branstetter's picture
Thanks Ed. It was a very fun build. Can't wait to see yours!

Shawn Branstetter
shortlinemodelers.com

eTraxx's picture

Be a bit .. working on cribbing at the moment. I have been putting laying the On18 track on the back-burner .. at least partially because I need something like this. Think I will push to the fore-front.

Shawn Branstetter's picture
Will the plans work ok for you?

Shawn Branstetter
shortlinemodelers.com

eTraxx's picture

Oh sure, no problem. I can easily extend/narrow as needed and keep the other dimensions.

eTraxx's picture

I'm tossing this up for comment. I used your basic design for a starting point for my On18 bridge. On18 is O scale on N scale track. That means that it represents around a 17" gauge. That 17" is 30% width of standard gauge. While not exact (people, seats etc. don't scale down) .. if you scaled down a standard gauge loco it would contain .027 the volume. That means a 40t standard gauge critter would only weigh 1t. Just something to keep in mind for this bridge. I kept Shawn's 8"x18" stringers but reduced them to 4 and grouped them under the track. I have some 5"x7" On30 turnout ties that I will use for the bridge (like the Narrow Gauge guys .. I like to use what's 'on hand'). They are spaced about 18" apart simply to make them come out even on the end (the bridge is 24' long). I added an outrigger stringer to support the walkway. That walkway is simply 3' wide with 4"x4" posts. Railings are 1"x4" boards, center and toe boards 1"x6'. Every fourth tie is extended out enough for a cantilevered 2"x4" while the rest extend out to the outrigger stringer. The bridge seats are 12"x12' timbers .. that top piece is wide enough to support the outrigger stringer and the bottom one just extends out an additional 12". The other side simply mirrors this. There will be a retaining wall/abutment prob made from the same 12" sq timbers.

The actual sizes I use of course will depend on what I have in my lumber stack!

Shawn Branstetter's picture

I really like the concept. It does look like it belongs in on a mining railroad. As you know Ed, the lighter equipment won't require such heavy timbers as the original drawing. I think this will work well with the lighter 18" trains. I do think the stringers are a little larger than needed. You could probably get away with 8"x12" boards instead. I’m looking forward to seeing the finished bridge.

Here are some inspration links:
http://swpare.blogspot.com/2011/02/ptmarion-pa-railroadmine-bridge.html

http://www.panoramio.com/photo/11401747

http://www.flickr.com/photos/matthiashn/4500427733/

http://www.railroad-line.com/forum/topic.asp?TOPIC_ID=14692

Shawn Branstetter
shortlinemodelers.com

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