"Too Sexy!"

Doc Hemp's
Technical and Engineering Page
For Our 68.5' Free Span 8' Wide
Sub Divided Warren Truss Steel Railroad Bridge

(Updated 11-26-05)

This page has larger file jpeg photos of scaned print and will take a while to download if you don't have at least DSL .. So .... Go play with your train ... have a few beers ... and when you come back the page should be as loaded as you are. (grin)

If you are contemplating such an adventure I would suggest perusing Omer W. Blodgett's book, an engineering and welding classic no longer in print ... find it used at Amazon.com and on E Bay ... Titled "DESIGN OF WELDED STRUCTURES"

I started this project at the behest of Melvin Harris who did the rough draft of this Warren Truss Bridge on his kitchen table. After welding over 1/3 mile of steel ties every 2' he felt I was getting experienced enough to go for the big one! ... Melvin has designed and built several smaller and successful bridges himself. Dave Moeller then took it from there with the engineering. Dave is a mechanical engineer and is a retired Corporate President of Simpson Lumber Co. He oversaw the engineering and building of Simpson's Co-Generation Plant. He has also observed and followed the welding and building on my engines, etc. at Melvin's ... Harris Locomotive Works and of course my building of the track and bridge.

We also ran our early design by my friend Todd Gandy too, a structural engineer who had designed and engineered commercial bridges for a firm out of Sacramento .. He and a friend crunched all the numbers on a computer program of our basic design .... With that early design he suggested probably a center pier for a really good safety margin .... Dave Moeller and I then beefed our design up SIGNIFIGANTLY plus I decided to widened the bridge 2 feet and add the full Warren Truss to the floor for more lateral stablization and room to drive my tractor over. All with Dave's and Mel's blessing.

I want to thank David Moeller for most of the photographed material below , which we looked over during our own design of our bridge which is unique to our Grand Scale Train situation.
11/20/05 .... After testing the center load deflection of this bridge which was only 1/2 to 5/8ths of and inch, everyone now thinks we will be able to run a tank over this span without a center pier ... Plus .... The train even double headed is over 65' long and the weight will be dispersed over the entire span. But If I do add the center pier later, I will build it out of steel to match the bridge. We already have it designed.

I also want to thank John Parks of Parks Welding (noted on our other page) for his instruction and his affirmation of using the 7018 welding rod on building the bridge ... I was welding a little to fast, which is the most comon thing for all welders. And he showed me some of the tricks, an easy way to start and hold the 7018 welding rod, etc. I had my welder set up just perfect which was good to know for sure. He also affirmed my plan to first spot weld with 6011 rod each area kitty corner like one would tighten the lug nuts on a wheel ... I spot welded each entire side first! ... Then finished all with 7018 welding rod .. We got ZERO WARPING OR DISTORTION IN 70' ... That was really great! The penetration was excellent ... we could see the outlines of the welds on the other side of the steel ... all basic welding technique. It took us forever to even grind off the 6011 tack welds on the top temporary support bars it turns out we didn't even need because of the way Glenn the crane operator rigged the move. We needed a 100 ton crane because of the long reach required to place the bridge across the ravine.

We started our Warren Truss Railroad Bridge Dec 3, 2004. All is structural A36 steel. The sides are 4' tall. The upper, side and lower rails are 3" X 3/8" angle iron. The spokes and centers are 2" X 1/4" angle iron. The floor is 8 feet wide with 3" X 1/4" Channel welded back to back to form 3" X 1/2" eye beams every 8 feet across with both track rails welded across over each one! ..plus 3" X 1/4" Channel on edge every 4' across with both rails welded to each one .. and 3" X 1/4" Channel on diagnal from each joint in each direction making the floor into a solid Warren Truss design too. We also have Knee Braces that are 10' X 2 1/2" X 1/4" angle iron coming the full lenght underneath every 8' and tying back up into the top of the 2" side rails for lateral support. The bottom rails are 3" X 3/8" X 68' 5" Angle Iron. And the upper rail is 3" X 3/8" X 60' angle iron with 3" X 3/8" Angle Iron tying the top and bottoms together. All 3 way junctions have 1' X 6" X 1/4" gussets welding all the angles together too.

Oh .... And last but not least ... The next time you are in a Wallmart ... look up at the infrastucture of the ceiling .... All Warren Trusses just like ours ... With huge spans and huge loads on them ... And in the Great Mall near San Jose ... They made all their T beams by welding 3 X 3/8" angle iron back to back with skip welds under the joints only and then bolted the spokes in so they can remove them and use them again if the configuration of the mall is changed. The bolts are not as strong as a weld but plenty strong enough. Melvin Called our attention to Wallmart's ceilings too before we started. Also ... almost all freeway overpasses have Warren Trusses across them under the concrete.

We ended up just as level on the abutments as I had it on the ground before the move

Abutments (first page only)

Trestle Center Supports (first page only)

  1. Basic Bridge Design Site
    Thanks Russ Robinson .... Who is now building a wood bridge 12/01/07
  2. Return to Building the Warren Truss Page
  3. Return to the Moving & Testing of the Warren Truss Page