Building A Bridge

gerard · Aug 22, 2002

ok, try again - your span doesn't look that long, you could pour footings using a post hole digger, sona tube and concrete, level from side to side. Price some steel I beams that will span the distance. Space them a width that will be about the same as tire width of the vehicles that are going to cross it and use PT 2x10 for decking cantilivered wider than the beams by maybe a foot in each direction. That should be sufficient for tractor travel. You could still do it all yourself and place the beams with your tractor/loader.

MarkV · Aug 22, 2002

Dave,
Would it be possible to cut the high side down, say 2’, the width of the road and hold the slopes back with some kind of retaining wall. My thoughts are that if you have a 4’ drop on the low side it will take quite a bit of building to form the road at a comfortable grade. It sounds like a lot of concrete and fill, which will add to the cost considerably. I have never built a bridge abutment but have done a fair amount of footings and concrete walls. It isn’t easy work but is do able. Given that you are in a flood plan and the Corps of Engineers will be involved I would find an engineer to help with the specs. I would bet that the Corp requires plans signed off by an engineer before they issue approval anyway.

Keep us up to date, it sounds like a fun project.

MarkV

Ozarker · Aug 22, 2002

This Military Field Manual might be some help.

<A target="_blank" HREF=http://155.217.58.58/cgi-bin/atdl.dll/fm/5-428/toc.htm>http://155.217.58.58/cgi-bin/atdl.dll/fm/5-428/toc.htm</A>

Anonymous Poster · Aug 22, 2002

I built a bridge across my creek almost ten years ago. the bridge is 32 feet across. I used a 4 post construction, After consulting the few poeple that i though could help me with some idea's on what I needed to do to make this stay in place, and also last. Well there thought where to sink 4 or 5 foot concrate footings, build from there. I wasnt willing to do that do to the stones and rocks in the ground.
This is what I came up with. 1st thing is to make a foundation with stones #2 from a area gravel pit.
2nd was to get some round concrate pads ( like the ones you would use for a stepping stone walk way ) Then I drill a hole in the center of the pad so I could run a length of rebarb though the pad into the bottom side of the 4 post.
3rd was to make a frame for the bridge. I used some 8" x 8" beams. Make these into a frames that look like a big H. these are what the rest of the bridge is mounted to .
4th is to run 3 or 4 beams from one H frame to the other across the water area. How menny beam you need to run across depends on how wide you want to make your bridge. I used 3 beams and my bridge is 8 foot wide.
5th make 2 ramps, One for each side of the bridge. theses 2 rams a some what hinged so they can move up and down as the season changes. As i do live in wisconsin.
5th is to cover with 2"x6" treated boards. This should do it for you I hope.
NOTE everything is bolted togeather except the 2"x6" treated boards they are screwed down with deck screws.
SORRY THIS IS SO LONG BUT I HOPE IT HELPS YOU OUT. GOOD LUCK, AND IF YOU NEED MORE INFO EMAIL ME

Anonymous Poster · Aug 23, 2002

I built a bridge a few years ago for a friend. It crosses a slew on a major river and has since been completely flooded over nunerous times. The bridge has a 30' foot span and is manufactured from an 8" beam that weighs 10 pounds per foot. In the center of the beam there is a 3' kicker running down. I stretched 1/2"X2" flatbar from one end down under the bottom of the kicker to the other end of the beam. I spliced in a 2' turnbuckle on the piece of flatbar so I could preload the beam with about 2" of arch. Two of these beams were placed far enough apart for a 8N ford wheel width. 2X8s were then bolted down to the beams. This bridge is frequently used to cross the slew with tractor and disc.

RobertN · Aug 28, 2002

I do not know how to build the bridge, but can mention safety... It appears this is just a bridge for a tractor, but think of what else might travel over it.

We see bridges that we can not take our Engines over. This is more of an issue for accessing a house during a fire or medical aid. It is not unusaul to have to park and hike in.

jtcweb · Sep 7, 2002

The house will not be behind this bridge, and any heavy equipment could go around the road and get to it across a neighbors land. But I want to have my own bridge for my tractor so as not to wear out my welcome with the neighbors.

jtcweb · Sep 7, 2002

I see that I miss-typed, my tractor is a 9n, precussor to the 8n. I just want to get to the back half of my property to mow. I can also see pulling a trailer to carry stuff back and forth, but for heavy access I can go accross a neighbors property that is at right angles to mine and comes out to a road. But generaly I don't want to drive a mile just to get across the creek. I would like to just put across some I beams and deck it, but I don't know what beams to use and don't have access to data sheets on them. Is "W16" & "W14" standard beams that I could buy at an iron shop?

Ozarker · Sep 7, 2002

W16 and W14 are standard but you need more information than just how deep (high) you want it. "I" beams are rated by depth (height) and weight per linear foot. A light W16 would be a W16X26 meaning that it is 16" wide and weighs 26lb per foot. A heavy one would be a W16X100.

Of course for each different weight the flange width, flange thickness and web thickness is different and all those variables go into telling you how much weight it will support over various spans.

Darren · Sep 10, 2002

Gator, if you're building anything in the 100 year flood plain, you might need a permit. I'm involved in a similar project and to satisfy FEMA, the county commissioners have to review and approve anything that may impact a hundred year flood. FEMA doesn't have a problem if the structure doesn't increase the flood elevation over a foot. Beyond that the FEMA maps have to be redone. You get to pay for that.

If a permit is required, you'll need to prove to the permiting authority whether or not your structure will cause the one hundred year flood elevation to increase by more than a foot. An engineer can review what you're planning and make a determination of the impact on the hundred year flood. Figure about $1,000 for that.

If there is no FEMA map for your area, you're home free.