Building a bridge in a flood plain?

[paintman161]

Just a thought here...

What's the bed of the stream like? Deep silt, or gravel? If it's relatively level gravel, how about building a concrete pad about 8' square, and 4' below your regular crossing height, with a veritical wall up to the road way height. On the other bank, put in a ramp that ends in another concrete pad, except now maybe just 6" to a foot below roadway height. You have basically just made a loading dock and a rest for the kingpin plate for a highway trailer.

Then get a used 40' flatbed trailer that will no longer pass road inspection. It already has the wheels and everything. Hook a chain to it and pull it across and out the ramp when foods threaten. Even if the floods take it away or wrap it around a tree, dig the debris off your concrete pads and buy another old flatbed trailer and you're back in business.

Even if the stream has a muddy bottom, you might be able to put in enough large rocks to make a stable enough bottom to wheel your trailer across when you need to.

that sounds like a lot of money, plus i have not place to tow it out of the way, there are steep banks on either side of the creek (about 300' away) and too many trees to maneuver it around.

 

[Depmandog]

I used the GPS coordinates...not much help. I suggest if you want some quality ideas.....how about some pictures???????

 

[bcp]

Google aerial

 

[GLyford]

Hunh, and I thought I was giving you a low-cost option. Heck, there's even an add for a 37' camper for free in my local craigslist, you can't get much cheaper than an old trailer for structural bits. Even if you have to cut it apart and haul the rails through the woods one by one, then bolt the pieces parts back together once you get there you'd still be ahead for a starting point. Especially for anything close to 40'...that long a distance is going to set you back a good chunk of change. Price anything else against a couple grand for a used worn out semi trailer.

As to the concrete, I was thinking a durable base that wouldn't get washed away...but you could just as easily rest your trailer ends on gravel or rocks, anything you can get to where the bridge will be that will drain easily and not hold water against the frame to make ot rot or rust out. You might have to do a little more work getting it all back in position after flood before you set your bridge back on it.

One way to make a sort of concrete bulkhead for either end of your bridge is to just stack up bags of concrete, paper and all, like bricks. Then drive rebar down through them to hold them in place in a few spots. The rain and ground water will get into the bags and set them over time. There's a couple other posts on TBN here somewhere where people have done this for the ends of a culvert and such.

So, in addition to the stream itself, access to the site seems to be an issue for you. Anything else?

 

[Depmandog]

Google aerial

. I was thinking boots on the ground, using the old camera and taking a few pictures, but hey...it might be just me that's having a problem visualizing the best bridge design.

 

[paintman161]

. I was thinking boots on the ground, using the old camera and taking a few pictures, but hey...it might be just me that's having a problem visualizing the best bridge design.

well this is at my property which is 30 miles away, I am hoping to be up there this weekend, but that depends on if we are going to get hit with another snow storm.

 

[Josh Shoemaker]

Just get permission from the neighbor that is just to the right of where you are at. There is a bridge just to the right of where the property is.

 

[paintman161]

I can get the bridge over there and down into the spot but Once i get the bridge down in the bottom I wont be able to get it back up. Its kind of like a large bowl in there.

 

[MotorSeven]

My creek is 35' bank to bank and the banks are almost 8' high. Seasonal flooding(winter) will see water over the banks in the place I built the bridge up to a foot. I used a 80' mobile home frame, and welded it in three sections so it looks like an open "U" which raised the main section of the span about 5' above the max flood stage. At each end I poured a concrete footer and bolted the frame to it, then made the approach out of gravel so it could be replaced if the water got that high and swept the gravel away.

I have not driven a wheeler on it yet because I have not reinforced it yet and I am pretty sure it would collapse. It needs two power poles sunk at each end and the sides of the bridge lagged or bolted to them. Then a cable run from a ground anchor up and over the tops of the poles across at about waist high with connecting cables running down to the bridge every 10' or so. Once this gets done I would have no problem driving a wheeler across. Some pic's:

 

[MotorSeven]