So your ruling out a stone archIf you can't do a low water bridge which is either gravel or concrete I wouldn't use anything except I beams and bridge planks
i share the same concernFinding firm soil for any bridge will be tough. And, if it floods, amazing what water can move.
No doubt about it. Picking up the pieces of your expensive bridge down stream is very humbling. Low water bridge IMOFinding firm soil for any bridge will be tough. And, if it floods, amazing what water can move.
As other said, the power of water is unbelievable. The first super hard rain we had lifted this bridge up, turned it 90 degrees and took it about 300 yds downstream, I’m still in shock over that!!! The work to get that thing back in place was an entire day with several people and 2 large tractors!! Since then we have staked down all 4 corners with some thick angle iron about 4’ long and bolted it to the bridge, we also cabled off the 2 upstream corners with some 1/4” cable and it hasn’t moved again in the last 8-9 years.
We built one about 10 years ago that has worked perfectly. The creek is about 20’ wide, banks are 3-4’ high and the water is less than a foot deep except for when it rains. I bought 4 telephone poles and cut them to 25’, we cut the banks back far enough for the 4 poles to fit down in the banks so there wouldn’t be a hump to drive up on, we laid all 4 poles side by side across the creek and then used pressure treated 3” thick X 12” wide X 10’ long lumber as the cross pieces on top of the poles. We put two 8” spikes thru the cross pieces into each pole for a total of 8 spikes per cross piece.
The bridge works like a champ, we drive trucks with a ton of feed in the bed and tractors over it with no worries, we almost took a lime truck over it this year but backed out.
As other said, the power of water is unbelievable. The first super hard rain we had lifted this bridge up, turned it 90 degrees and took it about 300 yds downstream, I’m still in shock over that!!! The work to get that thing back in place was an entire day with several people and 2 large tractors!! Since then we have staked down all 4 corners with some thick angle iron about 4’ long and bolted it to the bridge, we also cabled off the 2 upstream corners with some 1/4” cable and it hasn’t moved again in the last 8-9 years.
I was reading waiting for a cable comment! Easier to cable both far side ends so the bridge can swing out of the flow plus not trap debris. That way a single tractor on the near side can pull the bridge back into place after somebody crosses over to attach a cable or chain.
That sounds like it may work in situations where you have a tractor close by and don't use the bridge much but wouldn't work for us, we use the bridge a couple of times a week all year and a tractor is about a 1 hour round trip, definitely wouldn't work. After the initial problem with the bridge it has been trouble free for probably close to 10 years now, it sometimes has a little debris on it after a heavy rain but it doesn't hurt a thing.I was reading waiting for a cable comment! Easier to cable both far side ends so the bridge can swing out of the flow plus not trap debris. That way a single tractor on the near side can pull the bridge back into place after somebody crosses over to attach a cable or chain.