Building A Bridge

[ScottAR]

Our County uses old railroad flatcars for a quickie bridge. If I remember, they buy them for about $800 and cut off everything that doesn't look like a bridge. They use two side by side but one would be plenty wide for an 8n. One would need a crane however. Just an idea.

 

[yooperdave]

Have you considered a couple steel beams with a concrete pier at each end? There are steel fab shops through out the country, and they should be able to deliver. You could have a heavy timber deck (at least nominal 3") and have it cantilever over each of the beams a couple of feet. The beams would be centered directly under the tractor wheels.

Are you pulling anything heavy with that tractor? Like all small bridges, the safe load carrying capacity envelope will be stretched to new limits. Somebody will have a good reason for transporting a dozer or backhoe to the other side. Make sure your beams can handle the future needs of the bridge.

I am guessing W14 or W16 steel beams and some nominal steel bracing would give you a life time of support.

Let me know if you want some sizes and specifications to pursue this route.

Yooper Dave

 

[Ches]

I have just completed building a bridge across the spillway exiting my pond (so I can get across to the other side when the pond has overflowed). Used two 24 foot telephone poles. Dug two thirty inch deep holes (using 9 inch auger for support in center of spillway and used pieces of telephone poles (cut to length) set in concrete to support middle of bridge. This gave me about an eleven foot span on both sides of the supports. On the ends, I dug twenty-four inch holes (using 9 inch auger) and set 3/4 inch threaded rods in concrete, leaving enough length of the rod obove grade to go through holes bored through ends of the poles. After concrete set for a week or so I put the poles in place and bolted them to the rods. I acquired 2 inch rough cut oak from a local sawmill and used them as decking using landscape timber spiral nails. I've been told this bridge will be here when I'm gone.

 

[woodmills1]

I have seen plans for laminated wood bridges. these are made of 2 by stock placed sideby side on edge as if you were making a large counter top. for a 20 foot span you could use alternating pine 2x12 and hardwood 2x10. the pieces are held to each other with nails and then threaded rod is passed through drilled holes. the alternating 10 and 12 gives a better traction surface. I will try to find a link to what I think is a state of NH pamphlet that I saw this in. Hey I found the booklet it is a UNH COOP extension publication entitled User friendly guide to timber bridges. try this site http://ceinfo.unh.edu/fgen1043.pdf

 

[mrcaptainbob]

Do you mean that the 'bottoms' would be even and the difference would be at the top? Not knowing ANY thing about this, BUT (Always got to have one of 'em..../w3tcompact/icons/laugh.gif) it would seem that the 'trough' would collect water and speed up rotting........

 

[Gatorboy]

I have seen some plans also, but what I can remember, the laminated wood was used to make stringers and then 4x4, 6x6, or 8x8's were used for the decking.

I still have not started my bridge (25-30' span), and have had several ideas, but have yet to pick one. I am trying to create a bridge that I can build by myself (with the help of a friend or two), that will be relatively simple to build for the least amount of money.

My original requirement was it needed to be strong enough to carry a Fire & Cement truck -- but I have since created a ford that can be crossed for emergencies and concrete delivery. I just don't want to have to drive through water everyday with my personal automobiles.



- Gatorboy

 

[cj7]

I have seen used flatbed trailers for bridges around on local farms.

 

[Nick_D]

Here are some precast prestressed concrete girders we set today. Its for a multi-use (bike path) project which includes four bridges and 2.5 miles of fiber mesh reinforced concrete path.

Beams are 120 foot long and weigh 125,000 lbs. What a rush.

 

[pajoube]

Do you have two cranes (one on each end) lifting?
PJ

 

[Nick_D]

Yes, we had to pass the beams across the channel. One crane was a 190 ton hydro and the second a 110 hydro.