I want to build a bridge over a creek, it is about 40'-0" from edge to edge. Most of the year the creek is below the surrounding banks. But once maybe twice a year (depends on how much rain or snow melt) it does flood the surrounding areas but goes down within 2 days. I would like to make it 5' wide to drive an ATV across.
Is there any way to do this without having the bridge float away when the water floods the area?
thanks!
I read through the posts on this and did not see any real answers to the questions folks asked in trying to help you. It is hard to visualize your problem. There are a lot on innovative guys on there with a lot of varied experience. I have built expeditionary bridges out of many things but never quite as long as you indicate. I have been in heavy construction all my life (50+ years).
Important Questions:
-what is the normal water level (distance below the top of bank to water
-how high over top of bank bank does the water get in flood stage
-how fast does the water flow during flooding
-at flood stage how far out does the water spread from the 40' you are planning on the bridge to be
-what is your budget
-can you get a concrete truck to both banks
-if not, can you mix concrete on both sides
-are there trees on both sides that will support rigging tackle to drag the bridge across with
-can you get pickup truck or tractor to both side
-can you get a semi truck to one side
-what equipment do you have, can borrow, rent, or need to buy
First thing you have to do is plan. A project like this you cannot start and let it grow as you go.
A 40' span was mentioned but that may be cutting it too close to get a good head wall installed on each end.
My thought is a 53' semi flat bed trailer from a truck wrecking yard. You should be able to get one for a little more than the scrap value as they do not have to cut it up. You want one rear axle left on for over the road transport. Get it to one side and park at right angle to the creek. Lift the 5th wheel end and cut away the 5th wheel and landing gear to leave smooth rails Rig a haul line, preferably with a winch anchored 5-6' above the ground if possible. Drag that end over the creek and center the length. Drop the haul end for now. Lift the rear end and cut away the spring hangers to leave smooth rails on that end too.
Now you are ready to do the head walls. (If you can plan and layout well you can do this ahead of moving the trailer over the creek.) This is where site conditions dictate method so you will need some local advice on how deep and wide. You want at least 2 yds of concrete on each end more if you need to get deep to get bearing (that is a good reason to go 53'0 to get away from the creek mud). Make them 2' longer that the bridge deck is wide and 18" wide. The higher you put the tops above the ground the harder it will to place the deck on it. I would make close to ground level if you don't need more elevation to clear fast moving creek water. Saves forming above ground also. After curing gradually lift and move the deck over the head walls a little each side at a time till in place. If you can afford a crane now is a good time to do that instead. There are many ways to get the deck in place including doing the head walls first and setting as part of the move across the creek initially.
You will have to fill in all the little details this book does not have space to do. That is why this is not a project for a novice with no construction experience.
Keep us all posted as you go along with lots of pictures.
Ron