Building a bridge over a stream ...

[starsandsun]

Hi - I am looking for advice on how to build a bridge over a stream that can support horse traffic.

The stream itself is about 4 feet wide; there is a fairly straight drop on each bank down to the stream, and that drop is about a foot from the edge of the bank to the water. Also, there is a grade on each side of the bank with about a 30% slope from level ground across 10 feet to the water’s edge. I hope I’m explaining this right.

I was thinking of 6x6s as the framing to go across the bridge, and then 2x4s across the framing (maybe 6 feet wide?). I would like to have the bridge go across the stream and not across the full grade to where the ground is more level. I am unsure how much more reinforcement is required, and whether there needs to be any stabilizing (posts in concrete?) on either side of the bridge itself to hold it in place so it won’t shift when horses walk on it.

Any thoughts?

[2tempe]

No builder here, but I would for sure put posts in concrete weather and water will make them shift, not just the horses. Fence builders put even the posts for a 12 foot section of picket fence in concrete!

[Where_sMyWhite]

If I was planning on horse traffic, I’d be considering asking a professional to build/install it so that I felt safe using it and felt that anyone else using it would also feel safe (and so so I’d feel a bit protected in the event of falling off the bridge or it collapsing, an “amateur” bridge installer wasn’t culpable).

[BarnField]

What about a corrugated metal/pvc pipe sized large enough to accommodate the stream. You can even set several pipes next to each other in a row. Then, dump lots of gravel and fill on top of the pipe. I’ve seen that done nicely and you can drive a truck over it… its a whole lot LESS scary looking for a horse than crossing a wooden foot bridge… and there’s no lumber to rot/fail.

http://www.danieldean.com/wp-content/uploads/2013/10/small-creek-crossing-culverts.jpg

http://mediad.publicbroadcasting.net/p/wxpr/files/201610/Culvert.jpg

https://www.treefarmsystem.org/stuff/contentmgr/files/2/4ccd7b509178101845511b8e2eb60234/files/culvert_image.jpg

[Guilherme]

Contact your local Extension Agent or Soil Conservation office. They have a lot of information and advice on projects like this.

G.

[gypsymare]

How far across will the bridge actually have to span? Six by sixes are not appropriate for bearing a load from the side. The thickness of the lumber is not going to give you any additional load carrying capacity. You want width to the lumber like sandwiched 2x10s or 2x12s oriented so that the widest side is vertical. Think of the web of an I beam or the header over large open side of a run in or garage door.

I’d talk to an engineer about the design. 2x4s are not going to span 6 feet and carry much weight either.

[danacat]

My contractor built me a bridge across a stream this summer.

He put a twently foot plastic culvert pipe – over 2 ft. diameter-- into stream on a bed of gravel. Then he put these big plastic flanges at each end (one either side of pipe) to guide water into pipe.

Then he filled around pipe, over pipe and up to the back side of the flanges with crushed stone, then topped the whole thing off with lots of stone dust – blended stone dust to grade on either side of stream bed all the way back to dry ground .

Voila - super sturdy ‘bridge’ – more like a path over the stream – does have a slight hump in the middle where the pipe is buried, but it’s gradual. Not really all that noticable.

Cheap and fast. Will last forever.

[DiamondJubilee]

We did what others suggested and used a culvert, put some larger stones around that and then put screenings on top of that. We can drive/ride our horses over it and have driven our tractor and cars over it with no problem. It has held up well and still looks good several years later.
Our stream was not large, but I’m sure several culverts could be added together to span the width of yours.

https://scontent.fyzd1-1.fna.fbcdn.net/v/t1.0-9/10686763_10155193266100046_8892957454962846640_n.jpg?oh=459d7e1a342a7c7aaa9fbdf535641ec1&oe=58EC2B86

[ASB_Stars]

My neighbor just got ready to do this- and another neighbor noticed, and contacted DEP. Stopped him dead in his tracks. That particular stream is “exceptional quality”.

If he had built anything, and DEP came in and took issue, they’d have had him tear it out, along with possible fines, etc.

So, in an abundance of caution- I’d contact your local environmental concerns, including DEP, prior to starting.

[poltroon]

Two things:

1. As ASB Stars mentioned, there may well be environmental regulations that affect what you can do here. Anything that involves you putting timbers or a culvert into the streambed itself is of concern, both in terms of the law and in terms of your own wishes to protect the quality of the watercourse.

2. Your bridge needs to consider not just ordinary conditions for this stream, but 100 year flood type conditions, which could mean that the waterway is full all the way to the sloped area, for example. If your bridge is lower than this, it could fail (which might not be bad), block major debris (which might be very bad, creating an inadvertent dam), or create a lot of damage when it comes out.

I’d find someone around you who knows about these things and can look at the stream and can give you advice.

[DHCarrotfeeder]

The stream you describe is the size of the one in my front yard. Only my driveway crosses it and the bridge is a whole bunch of concrete and two 24" or 30" heavy-wall steel pipes embedded within it.

I would be much less concerned with the loads coming from above and much more concerned about what happens when you get floods. It takes just a few well-placed branches to clog the pipe and produce incredible hydraulic loads. Since I suspect you don’t want a tall, wide bridge I think you’ll need something low and sturdy like mine.

[Libby2563]

When I first moved my horses home, the stream between the barn and the pasture was spanned by a wooden bridge. It never felt safe for horses to me. Too slippery, and I was worried it wasn’t strong enough.

I had a local contractor replace it with a culvert like others describe and it has worked perfectly. Much much safer, and less expensive than the replacement bridges i priced. That’s what I would do if I were you.

[AKB]

In Montgomery County, MD, the park system commonly puts bridges across streams. Their bridges are well built and not slippery for horses. My horse will always select the bridge when he has a choice of getting his feet muddy by walking through the creek versus taking the bridge. Riverbend Park in Fairfax County,VA has some bridges. They put rubber mats down, which helps keep them from becoming slippery. Talk with the parks and see if they can share their bridge plans.

[Guilherme]

[QUOTE=ASB Stars;8984383]
My neighbor just got ready to do this- and another neighbor noticed, and contacted DEP. Stopped him dead in his tracks. That particular stream is “exceptional quality”.

If he had built anything, and DEP came in and took issue, they’d have had him tear it out, along with possible fines, etc.

So, in an abundance of caution- I’d contact your local environmental concerns, including DEP, prior to starting.[/QUOTE]

Ayup.

This is a main reason why I suggested contacting Extension or Soil Conservation. They will not only talk about best practices but also legal limitations. In TN there aren’t very many; in more regulated states they can be a Kafka-esque nightmare.

Research before you start digging.

G.

[Hilary]

Yes, if allowed, what we call a “causeway” is probably the best best. Big culvert pipe to allow the water to go through, and then an earthen ‘road’ across the top. Make it big enough to drive over while you are at it. We have 3 on our property and once every 50 years there’s a blowout flood that requires a rebuild, but it’s not expensive, can be an ambitious DYI but you will have to check with the Environmental regulators if you can do it.

[gumtree]

[QUOTE=Guilherme;8984888]
Ayup.

This is a main reason why I suggested contacting Extension or Soil Conservation. They will not only talk about best practices but also legal limitations. In TN there aren’t very many; in more regulated states they can be a Kafka-esque nightmare.

Research before you start digging.

G.[/QUOTE]

This would be the last thing I would do. I am all for soil conservation, realistic environmental rules and regs. Long before it was fashionable.

But like most if not all over stuffed bureaucratic regulators they feed upon themselves. Growing larger and bigger each year to justify their existence and budget. IMO WAY too many mountains are made out of mole hills.

We are talking about a VERY small bridge crossing one of most likely numerous small steams in the area. I think it would be a REAL stretch to think what the OP wants to accomplish is going to cause some sort of major environmental degradation. Something that needs a have an environmental impact study done. Lets be realistic here.

This will not take major money or effort to accomplish IMO and experience. I have built several. With much larger spans than 4+ feet.

IMO this falls under, build it and if for some reason some bored EPA agent stubble’s upon it ask forgiveness. This is private land not a state park or public. The worst that can happen is it may have to be removed. I would certainly take my chances on MY property.

The key to not causing any future soil erosion is not to disturb the existing stream bed. Pretty darn easy to accomplish with something this small.

Installing a culvert that is around 4’ wide is not easy nor inexpensive. This will require a reasonable amount of “engineering” to be done right, stand the test of time. If not done right there will be major soil erosion. I have seen many of these poorly installed and they have been a total PITA. Requiring constant repair and maintenance.

We have a small stream at the bottom of one section of our property that runs under the road. The state installed the wrong size culvert more than 15 years ago. The state has plenty of money and god knows how many “engineers” on the payroll. What do they have to worry about it’s not their money. They can’t get fired for screw ups. Unlike the rest of us.

Like most areas we get flash flood rains from time to time. Not something new, not something caused by global warming. Water seeks its own level and because the culvert was under sized to begin with the water backs up and flows over the culvert and the road. Never gets very deep but the state never put up a warning sign “Watch for high water”.

Instead they have sent crews out to dick with it year in and year out. Band aid fixes wasting god knows how much of tax payer money. Typical bureaucratic way of going about it, 3 people “working” 8-12 standing around. I know I’ve counted.

OP, pictures speak a 1000 words. If you post some pics, looking up stream, down stream and from both side I pretty sure I can tell you exactly how to go about it. Prefer not on Photobucket. Hate that sight. Slow to load full of BS and they send constant emails EVERYDAY when ever I check out someone’s link.

Post on FB which is far easier than Photobucket of crap anyway. Make the post “public” and provide the link.

This can most likely be a simple and fun project. But it may require far more effort and money than you want to put into.

Our fox hunters can easily handle jumping a 4’ wide stream.

[chicamux]

I belong to a non-profit trail organization that builds and maintains trails and horse/hiker bridges in our local state forest, in the state of Maryland. We have built a lot of bridges over a variety of streams with the permission of the DNR.

We do not disturb the streams or stream banks. Our bridges span from bank top to bank top and in most cases the bridge supports extend at around 4’ onto the banks on each end. Most of our bridges use multiple 6’x6’s of pressure treated wood, 3-4 per bridge for smaller bridges. We have built two larger/longer bridges with recycled power poles as the support beneath the decks. Our bridge decks vary, again it has to do with the bridge width and span. Some of the smaller bridges are decked with 2"x 8-10" pressure treated boards but the larger bridges are decked with 4" x 4"s. All of the bridge decks are covered with gritted roofing tar paper. It is wonderfully non-slip and works for horses, bikers, hikers.

Our “small” bridges really are for very narrow creeks. We do not use concrete at all. We simply dig and tamp until we have a flat level shelf for the ends of the bridge supports to rest on. You really want to have the bridge deck level, side to side and end to end. We also nail two slightly raised 2"x4" boards along the sides of the bridge deck. They work as “stops” in case hooves or wheels slide toward the edges of the bridge. Honestly the gritted roofing paper has pretty much eliminated slipping.

One last thing that makes for a horse friendly bridge is to nail “Cap” boards on the ends of the bridges so the horse doesn’t see the dark “Monster Filled” holes under the deck and between the supports. We all know that dark holes/tunnels are filled with horse eating monsters!

[gumtree]

[QUOTE=chicamux;8985046]
I belong to a non-profit trail organization that builds and maintains trails and horse/hiker bridges in our local state forest, in the state of Maryland. We have built a lot of bridges over a variety of streams with the permission of the DNR.

We do not disturb the streams or stream banks. Our bridges span from bank top to bank top and in most cases the bridge supports extend at around 4’ onto the banks on each end. Most of our bridges use multiple 6’x6’s of pressure treated wood, 3-4 per bridge for smaller bridges. We have built two larger/longer bridges with recycled power poles as the support beneath the decks. Our bridge decks vary, again it has to do with the bridge width and span. Some of the smaller bridges are decked with 2"x 8-10" pressure treated boards but the larger bridges are decked with 4" x 4"s. All of the bridge decks are covered with gritted roofing tar paper. It is wonderfully non-slip and works for horses, bikers, hikers.

Our “small” bridges really are for very narrow creeks. We do not use concrete at all. We simply dig and tamp until we have a flat level shelf for the ends of the bridge supports to rest on. You really want to have the bridge deck level, side to side and end to end. We also nail two slightly raised 2"x4" boards along the sides of the bridge deck. They work as “stops” in case hooves or wheels slide toward the edges of the bridge. Honestly the gritted roofing paper has pretty much eliminated slipping.

One last thing that makes for a horse friendly bridge is to nail “Cap” boards on the ends of the bridges so the horse doesn’t see the dark “Monster Filled” holes under the deck and between the supports. We all know that dark holes/tunnels are filled with horse eating monsters![/QUOTE]

Good post!

I’ve done the same for the AMC (Appalachian Mountain Club) in NH and Maine years ago.

This is a short span. On longer ones and horses you don’t want it to be too “lively”, have too much “bounce”, flexing when walking across. Some, a lot of horse’s don’t like that, they can freeze up halfway across.

My only concern, is the slope on either side being as the OP said, 30 degree. 30 is pretty steep most “expert” ski slopes are in this range. But most people are not very good judges of this so good chance it is far less. Which is why I asked for pictures.

Human foot traffic by and large wouldn’t have much impact on the stability of the soil on either side. But horses will have LOT more. They will dig into, tear up the banks. Rain runoff will create gullies in pretty short order. A lot of soil erosion into the stream and a maintenance hassle. Really depends on how often it will be used and by how many horses.

I would avoid using it when it has been raining and the footing gets muddy and soft.

[Hilary]

I’ll try to take some pictures of my causeways. (edited to add I kinda forgot about the snow and photo wouldn’t tell you much) We used 18" plastic culvert pipe, and the key was to build concrete forms for the ends to sit into. You will need a tractor with a bucket (or a backhoe),to fill in around it, and best to wait until the stream is about dry, if that ever happens.

When the big one washed out we tried fixing it before the water was down and the pipe kept popping up on top of the water.

As we were replacing existing things we didn’t need permission.

[ASB_Stars]

[QUOTE=Hilary;8985124]
As we were replacing existing things we didn’t need permission.[/QUOTE]

Unfortunately, this isn’t true.

You may absolutely get away with it- depending on how visible it is to others who might care, and to government guys, driving down the road. BUT, the bottom line is you do need approval.

My neighbor used to own the farm across the street, years ago, and farmed it with his Dad. The piece of it that he bought back from the developer is really nothing more than the stream, and wetlands, of various types. His attitude was that he had owned, it, he had farmed it, and he could do with it as he chose.

He started out by filling in the wet areas along the road, to put in a driveway. Well, this is a State Road, and he does know that he needs a permit. Ooppss. So, along with the issue with the stream crossing, he has caused himself some additional angst.

I don’t make the rules- I am just reporting them.

Once again, as long as you don’t get caught, it’s all legal, right? :winkgrin: