Need to build a small bridge

[Timber]

A friend of mine spanned a 25ft wide, 8ft deep gorge with a bridge. he used a 40ft flatbed semi trailer minus the running gear. Your smaller creek could be spanned with a 14 or 16ft flatbed off a straight truck real easy. They are bull strong and if you get lucky and find an old one with steel flooring, you'll never have to repair it. I'm sure you can buy an old flatbed way cheaper than building a bridge out of lumber. My friend dug his into the ground so it's level with the trail grade. Very quaint, out in the middle of a huge timber.

Now There you go I love that idea. See this is exactly why I love this group.

 

[MikeD74T]

Take a look at the Rainbow Bridge website. http://216.104.173.251/2060.html They have bridge truss plans that will support your weight. The weights listed are for a two truss bridge, but will hold double with four trusses, etc.

 

[Joe1]

The use of a flatbed trailer truck would make a lot of sense. They are about 8' wide and many have stake pockets where you could build in a safety rail. Once set in place, you'd be just about done forever.

 

[The Gardener]

You could consider three, steel, I-beams pre-drilled to accomodate pressure treated cross beams [each bolted down in place]. A local steel mill can meet this request. Bolted down boards allow for easy replacement.

Not sure of the cost, but it will outlast anything made of wood since rot is the number one issue. I plan to make three of these bridges to span a 6 foot drainage ditch running between all of our different fields.

I used a RR tie bridge for ten years. It was very good, but it sat fairly high, and I like the lower profile of the steel I-beam. I can definitely say that RR ties work great. The cross boards were spiked down, and they lasted about 9 years. The cross boards have begun to deteriorate. That's why I have decided to replace this design with a bolt design - once the cross boards reach the replacement mode.

Good Luck!

The Gardener

 

[PineRidge]

Don't know how a large diameter concrete culvert pipe could ever be an issue. They use them around these parts and the water moves through them without problems. Plus a section of concrete culvert has to be cheaper and safer than a bridge.

 

[ovrszd]

Don't know how a large diameter concrete culvert pipe could ever be an issue. They use them around these parts and the water moves through them without problems. Plus a section of concrete culvert has to be cheaper and safer than a bridge.

But a culvert is so boring!!!

 

[Bill Barrett]

I didn't think a culvert would be a issue either, and they are all over my area. But big brother had other ideas!

 

[dillo99]

I built a 16 footer using 2 x 12's. I used four of them as beams (nailed two together on each side). I leveled the ground to the right height and then attached the beams to a flat 2 x 10 x 8 on each end - think of that as a large pad on each end. I then added decking - 2 x 12's an put in some gravel to level the ground to the right height. The thing is solid as a rock.

 

[PineRidge]

I didn't think a culvert would be a issue either, and they are all over my area. But big brother had other ideas!

A few years back the wife and I decided that we wanted to extend the smooth bore plastic culvert pipe that extends under our drive at the street. The idea being that if there was no ditch, mowing would be simplified. I wrote a letter to local zoning board and told them my plan. Within the month they paid me a visit to check things out. Then I get this official looking letter in the mail basically telling me that permission was denied. I still have that letter filed away.

Just a couple of weeks ago a neighbor down the street did the very same thing that we wanted to do. I silently watched, thinking he would get a visit from the zoning police as the pipe lay out in his yard for a week before he even started. Then he slowly finished his project and I believe the grass was just planted.

I'm still going ahead with our original idea only this time we aren't going to ask anyone for permission and the work will all take place on a weekend start to finish. Get the idea?

 

[have_blue]

I built a 16 footer using 2 x 12's. I used four of them as beams (nailed two together on each side). I leveled the ground to the right height and then attached the beams to a flat 2 x 10 x 8 on each end - think of that as a large pad on each end. I then added decking - 2 x 12's an put in some gravel to level the ground to the right height. The thing is solid as a rock.

There ya go! QED!

Some people are a little skiddish about bridges. There's absolutely no reason to worry about a short bridge. A pair of knot-free 2x6's will hold up a 2000 pound tractor over a very short span. Build the bridge structure 10x stronger than necessary, and remember that for every extra 5 feet of length, your beams need to be about 2x stronger. A factoid is that could come in handy is that a 2x12 on edge is probably just as strong and stiff as an 8x8. A common unfounded fear is catastrophic failure of a wood bridge. That rarely happens on a long bridge, and almost never on a short bridge. Wood will give you plenty of warning when it's about to break . Even if it does break, it usually just yields a little and stops. Bridges spanning 15ft or more over deep chasms are another matter entirely, and I ain't going there!