I am considering purchasing a property next to a river. This property is remote.
Of course I would like to cross an atv to the other side. So I have been contemplating ways to make a cable bridge.
River is approximately 70 yards wide with steep 8ft banks.
Entering river is prohibited.


I have seen several old one lane metal bridges, but realistically they are overkill weight wise and not really long enough without extensive refabrication.

So for the engineers, what diameter of cable could be stretched across with decking over the cables.

Similar to

https://www.loscabosguide.com/loscaboscanyonbridge/

Not a bridge engineer, and never having constructed a cable bridge (but lots of other types of bridges), what you are proposing would be quite an undertaking. Quite an undertaking.

The attachment you had indicates 2” cable, but that project has a higher loading than your single ATV and the span is quite a bit more

Yikes! The link to that bridge you posted is pretty impressive. When I saw this thread title I was thinking something like an ag ditch. For an ATV bridge to span a 70 yard river you have way more faith in your fellow Campfire members than I do to ask random strangers for bridge building advice and cable tensile strength suggestions!

I would think the state or local government will want to be involved with permits and that you’re going to need a structural engineer consultant to sign off on it?

If you know anyone that's a lineman. talk to them about the the cable they use to guy utility poles, they call it strand and it comes in different sizes and has a very high tensile strength and is weather proof.
They also make a bunch of hardware for attaching and anchoring the strand.
Hope this helps.

I know the state guy and he said as long as the bridge was above high water, they would not get involved.
Bridge would not be public use.
The campfire wisdom is often like big stick’s postings. Somewhere inside is a shard of wisdom, often the rest is less helpful.
But it is pretty amazing the diverse backgrounds of this board.
I have also found that no matter what design is suggested, people have improvements to offer..

Is the river a navigatable river? Seems a single line with a ferry might be easier?

https://www.peninsulaclarion.com/news/russian-river-ferry-a-piece-of-history-still-afloat/

This might be the shard of wisdom....
figure a floatinhg dock in conjuntion with a winch on the ATV (and tie downs of course) you could pull off your own cable operated ferry then go with the $500 pedestrian suspension bridge as a back up...

Technically, navigable but after spring it drops to under a foot.
The above suspension is somewhat my thoughts.

Sounds like a fun project but not for the faint of heart.
There are many calculators on the interweb to help you with structural load calculations. The biggest variable will be your anchor points on either side. For example, a 100# load in the center of a 210' span puts many tons of "pull" on the end of your cable. The soil, rock, or whatever on the banks needs to be right. A couple rail ties buried a few feet deep won't touch it.

That's what I was thinking.

so fordable in the summer, but prohibited... what about a floating bridge? or is there a high probability of flood born debris taking it out?

It would be cheaper to buy a 2nd ATV and build a shed for it than a suspension bridge,that would get whiped out by a sawyer nxt big major flood

For another off the cuff unqualified comment,
That's a whopper of a project for a engineer alone let alone the construction process.

I'd have to think a single cable that could handle a cable car capable of carrying an ATV and a couple of people might ring in as more cost effective and require less engineering knowledge.

The bridge you've refrenced was created by a very knowledgeable architect (Enrique Norten). There are so many factors involved it's staggering.

Best of luck, hope your dreams become reality, keep us posted!

Very steep bank 8 ft plus sides and not able to place structure inside high water boundary.

I’ve built a couple as contractor. Both were more than walking bridges. The calculations involved from buckle points to cable strand to wind shear to dirt plus a thousand more were mind boggling. I saw them, thank god I did not have to understand or interpret them, just build to resulting spec.
Your asking about a very involved undertaking. Also don’t forget insurance. If you don’t think anyone else will access your bridge or you can keep them from it your wrong. Those are crazy magnets to people.
Be careful.
Osky

Definitely,
Soil is river bottom silt, concrete would be 100+ miles away.
I do have trackhoe access in neighborhood for deep anchor but an old dozer sunk into ground is probably more anchor.

This is hunting camp area.
The gondola idea was suggested by one of my siblings.

A 210’ span is not trivial. That’s a lot of load on a cable bridge, requiring some pretty substantial abutments, towers, and anchors. Got $50,000 “+ for materials, including concrete bases and footers. You’re talking like 35,000 lb+ end loads.

Now that's "outside-the-box" thinking. Reminds me of the Josie Wales movie. Missouri boat (ATV) ride!

Having worked with "real" bridge engineers, you don't want to get them involved.

This old bridge in so. Idaho was constructed decades ago for sheep. It's about 40 yds long. It originally had 4 3/4" cables although 1 broke over time and the bridge is now defunct. If 100 sheep were on it at at time, that would be 10 to 15k lb.
You need to use some of your college physics here. The tighter you stretch the cable, the stronger it has to be. If you let it sag, it can carry a lot more weight for the same size of cables. Of course you then have to climb the hill from the center to the far side. I can't remember the formula for figuring how much sag to get how much capacity.

I'm in the same predicament. I got a 100 yard span I need to get a sxs across. Usually under 6 ft of water but when empty, 6 feet of mud.

Alot of debris, ie:trees float down. Not navigable, just a swamp that drains into a creek.

Money so far is stopping me. 40 acres are just sitting there

Get the atv over once and leave it?

I’ve seen a video somewhere….


Zip line type. Hooked the atv to it and pulled it across.

I'm assuming this isn't in a "Wilderness Area" where vehicles are not allowed? Buy a second ATV, (and a canoe if need be). Used, in good condition, secured from theft.

I'm sure there's a way to get that thing over there.............. 8' banks aren't much, nor a foot of water if it isn't too fast.

A couple 16-20' 4X12s, low water and a dark night Monday to mid-week comes immediately to mind. You need stringers for construction on your structure, after all. OR in winter if river is frozen. It might even be legal then. . Not that I'm suggesting, you know, the thing....

Are you talking ATV or UTV? What weight? To get it over there at high water, you should be able to rig Jin? poles with block and tackle or pulley to one-time lower and raise the ATV up or down the bank, and a boat to get it across the river initially to leave there, then your dingy/ canoe or whatever to transport you back and forth across the river as needed.

If you are in snow country, take it in via snowmobile and sled in the winter, assuming there is a route, or if crossing/running the frozen river is legal in winter.

Dis-assemble the ATV, back pack it over, reassemble? Float/power boat up or down the river from an access point to your property at high water, then block and tackle it up as above? If high-water mark is near the top of the bank, and it gets there in the spring,or heavy rains, this would be easiest.

Depending on where high water mark is, constructing a dirt or wood ramp down to that may save some effort, if allowable.I like high water for this kind of stuff. Many years ago I had get some 30' green spruce logs to my cabin, from a quarter mile down river. Banks ( pure mud) are at least 16' high there at low water, with a willowed over bench about half way up where the trees were cut. I dropped the trees, power winched them over the bank onto the bench in preparation to complete the job piece by piece. I got lucky! A heavy rain came along and filled the river to the top, but my logs were still trapped in the willows. I just hitched them to the boat, one by one, and towed them to cabin, and power winched them from the top of the bank the 100' or so to the cabin. That's the easy way to deal with steep/deep river banks......

Stop thinking like an Alaskan, this is outside. We used to do stuff like that at bear camp out of Tok, won't fly down here.

My neighbor to the west knocked over a big maple so he could access his property across a creek. Someone bitched and state came down hard on him

To meet state regulations, you might end up spending more on engineering, permits, and safety issues than you spend on the bridge itself.

For the most part I'd say its not affordable.

Sling a wheeler in under a chopper and leave it.

Hey- I put a disclaimer in there. That's what you get for leaving.....

With 6' of water, a one-time boat/barge-across isn't doable for the SXS? Current a problem? Or legal access from the bank?

Maybe get some of those thick deck/pier styrofoam pieces, plank it over, then de-construct after use and sell off or use for insulation elsewhere? Flotation should be easy to figure. Don't know what you would do about personal-access during mud-time, unless it's zip-line.

My SIL and her husband put up one to access their island in the Stillwater from their mainland lot in Columbus. Probably about 50 yards long.

that would be a fun project to tackle if I was using someone elses money

70 or 100 yard of cable, strong enough to hold itself, decking,
and just 1 ATV@1000# plus.


How ya gonna attach the ends?
To what?


If you gotta ask about this don't do it!

Get an amphibious ATV.

Bruce

Not really sure what the Army Corps of Engineers might say about this project.

I hope youre getting the property for FREE! Otherwise, what damn use is it if you cant cross the river to get to it? How are you gonna get the cables across? Is wading/swimming allowed? LOTS of questions before I even attempt to contemplate a solution! Things just don't make any sense to me yet about how youre going to get over there the 1st time. Is this river flowing sulfuric acid or something?

The cable tie backs will be a significant challenge

From the cable bridges I’ve been on, the cable tie back anchors are significant. Quite a bit of concrete buried into the ground, and I would imagine an cable anchor assembly below that concrete. On both sides of the river.

Not sure how you’re gonna get that stuff to the other side of the river.

This project, as mentioned before, would be quite an undertaking

I would reconsider the single cable with a tether to a floating platform or raft idea. My thought is that would be the simplest, quickest, and cheapest option.

Big difference in a 54' foot bridge and a 70 yard atv bridge.4x the length and 5X the weight. Without a center support you're going to need pretty stout towers.

Good idea.

They use those ARGOs up in Alaska all the time for situations like this.

Saw a used one on Craigslist here in Arizona for like $15-20K within the last year. I remember because I was thinking WTF do you need an ARGO here in AZ for?!?!

You can count on both hands the number of flowing rivers in the entire State…………..

That is a long span!
The USGS uses a couple cable/trolley car setups to cross rivers up here. Single cable attached on both sides to big steel anchor platforms.

You see them in the Himalayas to get across the river gorges.

There are quite a few suspension bridges that have been built in remote locations that might fit your description of needs.

If you pound the hell out of the internet you might strike gold and come up with some engineered plans.

I'd focus on our government sites and projects such as National Forest, Parks, Corp of engineers and the like.

Maybe if some of the posters here might share the names of remote bridges that know of it could offer you some valuable key words for your search.

No matter what, soil conditions will vary in every location.
If I came up with a valid set of plans I'd still do a soil core sample and present it to a qualified engineer for instruction to proceed.

KOOTENAI FALLS SWINGING BRIDGE



http://www.fs.usda.gov/main/kootenai/home

BLACK BEAR TRAIL BRIDGE
FLATHEAD NATIONAL FOREST
Rehabilitation of a cable suspension trail bridge over the South Fork of the Flathead River on the Flathead National Forest. Project included improvements to approaches, repair of the existing concrete pedestals, corrosion protection on the steel cables, replacement of miscellaneous timber deck members and replacement of timber tower members. All tower materials and supplies had to be packed in 14 miles to the job site by mule train. Battle Ridge Builders worked closely with the Forest Service and the Packer to deliver a final product that was very labor intensive for both the crew and animals.

Owner: USDA Forest Service
Prime Contractor: Battle Ridge Builders

The far side is accessible during summer by going many miles around.
Inclimate weather makes far side access… challenging.
River crossing during hunting season in canoe could be done but I am not a competent canooer.

Only feasible way we could come up with is an old pontoon boat. Strip it down so just just base platform. Hook up a cable system and with a winch pull ourselves across. Around here you can find smaller pontoons for sale relatively cheap.

Right now we have a 10ft skiff. Works but still.

When no water, usually muck boots work but you will be a muddy mess when done.

If you decide to DIY a 80 yard suspension bridge, please take pics and videos and post them up.

It's "only" 70 yds long . . .

That was the very first thing I thought of “a missoura boat ride”

Actually, he said the crossing was 70 yards, which means the bridge, abutments, supports, anchors, etc... are going to be much longer.... especially since he can't build within the high water mark if I understand him correctly...

Personally, from a background of working in construction all my life and contracting 20 years of that, I'm thinking this bridge solution is going to be a money pit you are never going to recover from unless the property is really, really special in some way. Materials alone for a project like this are going to drain your pocketbook way beyond the value of the property IMO... when it comes to supporting things over long spans, the longer the span the more the cost multiplies by huge factors once you go over about 50 feet without midspan supports.

Time to rethink your plan for a more simple solution IMO.... maybe build a ramp on both sides and do an Evel Knievel when you want to access the other side?

Tsavo?

Im sure he will "sort it out"

Bruce

So why prohibited?

Well ain't that the shiitz Super cool!

My 2 cents.

1. find where you want to cross both sides.
2. Place rip rap on your bank, without it falling into the water booth sides. this will take a few truck loads, place with a loader. make the piles of rock quite high 8 to 10 feet.
3. next spring when you have high water, your rip rap should collapse your bank on both sides. have pictures that you did not place rocks into the river and that nature resulted in the rocks being in the river.
4. Place additional smaller rocks into your rip rap, this provided a mixture of large and smaller rocks. This is what you need to be able to drive on the rocks. A dozer is works best to packs the rocks after they collapse.
5. this should provide a entry and exit for both sides.
6. this may take year or two, however it works and you let nature have it way with river flow.
7. you did not say that you could not drive through the river at low water level.

This would be

To be clear, state law prohibits motor vehicles from entering water ways. (an individual could cross but is a crime to drive in riparian)



a person may not operate a motor vehicle or an off-highway vehicle below the ordinary high-water mark, as defined…
of class I or class II waters, as defined …that occurs on state or federal lands or below the ordinary high-water mark of class I waters flowing through private lands, within that portion of the streambed that is covered with water.

Has the State delineated "high water boundary"?

Average yearly?

5 year event?

50 year?

100 year?

Will US Army Corps of Engineers be involved? Wetlands involved?

How much driving do you avoid by building a bridge 210'+ long?

Interesting that ^^^.

So no low water crossings in the whole state?

54'

OP needs 70 yards.

Basically, if you don't have deep pockets, it ain't gonna happen.

Sell the land across the river to the adjoining landowners. Use the money to build yourself a nice rifle range and buy some more guns.

Bruce

Stream access is a complicated legal area that I am avoiding by going over. Including stiff penalties for unauthorized access or impacts.

The way around isn’t super helpful given that during hunting season it is not passable.

Remember folks, the Oregon trail was expensive…

Structural engineer here. You're going to need some giant ass towers, even more giant ass concrete abutments and some seriously big ass anchors for that cable. Not even worth doing the math. 210 feet is a huge span. I'd be looking at floating it across the river or getting an amphibious vehicle. For the price you'll pay for the bridge, you can buy a few dozen boats, and amphibious vehicles. Russia makes a nice one. Called the Sherp ATV.

https://www.youtube.com/watch?v=23I0YYgGVIk

Saw this one at SHOT show. Looks even better.

https://hydratrek.com

I've built bridges that spanned 30' ft or so, that we drive over with trucks and tractors, but never this long. So, I'm gonna admit, "This is above my pay grade".

Wish ya luck!

Umm, I just checked the price of a sherp-$110,000.
I can park a d9 dozer on each side with cables stretched between for much less?

Mountain10mm;
Good afternoon sir, I hope the day's been behaving for you so far.

As I was pondering a response you posted and I can only say "Amen" to it.

My background is looking at bridges built by the company my wife has worked more than 3 decades for.

Some of them were railway trestles rebuilt to match the original ones from the old days but now restricted to foot traffic only as well as some in more remote locations.

Up here across the medicine line the bill for the concrete alone would be considerable.

If one can't drive to the other side easily there's going to be helicopter time too, for sure for stringing the initial cables across?

Again, I've not been a builder of such, just someone who's looked in wonder at the finished products.

All the best.

Dwayne

The is the Dant ferry on the Deschutes. Might be cheaper to rig something like this.

A new D9 is $350,000 used maybe you could find for $80k. And you need two. One of which has to get to the other side. Plus you need to pay to have them delivered at wide load rates. Cable alone will probably be over $100,000.

elkmtb;
Good afternoon to you sir, I hope the day's been a good one for you.

Thanks for the video, I appreciate it.

We've been to Campbell River a few times, but not since the bridge was put in.

Here's a sight with a breakdown of the cost.

https://www.islandcoastaltrust.ca/p...frastructure/elk-falls-suspension-bridge

As mentioned I've got family in the business and I'd suggest that costs would be roughly 25% higher now.

Sorry to be a downer to the OP.

Up here the cheapest D9 Cat I found was $129,000 and it was an '89.

All the best,

Dwayne

The problem with trying to use an Argo to cross 70 yards of flowing water is he'll be a mile downstream before he gets to the other side, I've got one and no way in hell would I try crossing any type of flowing water. They work ok on lakes and ponds but are slow going and most people attach an outboard to it to push them across.

Cable is expensive, but not THAT expensive. I buy 9/16 swedge cable which is really 5/8 squeezed down, for about $2 a ft. If OP has something to tie it off to, I can stretch that cable tight enough to tightrope walk across that river.

I was thinking more along the lines of

https://www.machinerytrader.com/listing/for-sale/31618589/1985-allis-chalmers-hd21-crawler-dozers

A 44,000 lb concrete anchor would probably cost more, and an older version would probably suffice, and several closer in that county.

Y’all may be struggling with farmer ingenuity and oilfield supplies.

Build a storage shed across the creek and put your ATV there. Leave it there. Then a small footbridge shouldn't be too big a problem.

the Oregon trail was also dangerous and many people died...kind of like some of the homemade, cut rate bridges I've seen.

Build a storage shed or leanto on far side. Leave atv hooked to solar battery maintainer and a gas supply when you can access by vehicle. Build small personnel aerial tram to cross river.

Argo 6x6 listed for under $14,000

Can’t operate motor vehicles in stream.

Just where in the blue [bleep] are you talking about? You still aint ever answered us about that.

Any bridge built has to be rated for the most weight it will be subjected to, among a host of other conditions. Just because YOU will only use it to ride an ATV across(assuming you don’t end up REALLY needing to drag a heavily loaded wagon behind that ATV across it at some point), the point of the exercise is that the bridge needs to be able to support any load that might reasonably be expected to cross it. That includes unauthorized users, which a bridge being one of the most “attractive nuisances” there is, are a real concern. The only people who really do what you are talking about are government entities and a few private organizations with deep pockets.

In short, building bridges is for those who print their own money. I like the ferry idea. Even a gondola will not be cheap for the conditions. Cheaper to buy/build a vehicle capable of accessing it the long way around. Probably even cheaper to buy a helicopter(small one, Robinson or similar) and learn to fly it.

I have strung cables across rivers and it's certainly a job. Keep in mind that they will catch anything that won't pass under them.

I'd entertain the idea of a cable to cross the water well above the safe elevation. Set one dead end and the other could be live to allow rope sag for varied water elevation.

Davits on both sides to clear the bank issues.

Cross via small craft or "dock/flexi float...etc".

Use the cable to ferry across. Could be a rope grab and pull, a capstan on a ferry rope, continuous rope loop that's motorized.....your wallet is the limit there.

I'd keep the load bearing on the crossing to a minimum and rely on displacement math to figure out the floatation needs.

I missed this question, it is 20 acres in Montana.

If anyone I cared about was going to use the thing I'd engage a PE with some trail bridge building experience.

I have helped put up a few pedestrian cable bridges in the mountains but all were designed by a PE. I can tell you that they used actual galvanized bridge strand, not cables from Home Depot. Like this.

I can't speak for the OP but in my case, a bridge is out. Old growth trees that come down. Spend that kind of coin on a bridge and a tree takes it out...no thanks

Been looking for an amphibious vehicle but dam, if you find a used one you are paying retail.

Thank you! They wont let you cross a stream with a motor vehicle in MT? OOPS!!!!! I guess us crossing the powder river in a deuce and a half wasn't legal?

We had the property logged about 4 years ago. The hardwood guys were determined to get across the swamp. It was a relatively dry year. 1 small trickle of creek flows year round. It's about 2 foot across and maybe 8" deep. You could step over it.

They brought in pads to cross the trickle per the EPA rules. That skidder got a work out. They had to make 3 different roads through the swamp cuz of the mud.

The owner of the mill was out there one day watching the skidder. He told me I was lucky having signed this crew. No one else is crazy enough to try it.

Then the rain came, pads are still there and I still have 120 trees standing that were marked to be harvested.

Search 'helical piers'.

Dozer out each end ...then boat it .....

This bridge project sounds like some pretty high priced meat.

To access another 20 acres? Absolutely no disrespect intended, but I would use the funds some other way.

Bridge would open access to 500 square miles of public land.
Would offer a secondary access to property.

They used to have these little baskets suspended by cable out by the Milner dam in Southern Idaho when I was growing up. I guess the dam workers used the to shuttle across at some point. My friend broke the lock off of one and took it across one day. He ended up rely messing up a finger getting it caught in a wheel.

You could watch gold rush whitewater and see how they get stuff across a canyon to where they work. Suspending a basket under a cable may be the cheapest way to go.

Bb

Nice owning parcels of land on both sides the river directly across from each other. I'd be building a bridge too if I was that forchanet.

If you need cable rather than buy new find a construction company with a cranes and get their old cable. Unless things have changed with the srap people they don't want cable unless it's already cut up. Had a friend go to the Grove dealership and got all he cable he wanted for free. Built a 70 foot bridge up in the forty mile country that he is still driving his pickup over 15 years later.

Good call, I hunted with a guy this year that operates a crane that installs the turbines for big wind farms.
I will scrounge.

How long does Dyneema synthetic winch rope hold up in the sun? I'm assuming not long. It's incredibly strong for it's weight and you can get long lengths at a reasonable price. The issue would be whether it can hold up after years of sunlight.

salmon spawning stream? Irrelevant really. Illegal is illegal

You couldn't give me an argo or version of. I"ve been around them enough to know if you aren't a mechanic with a spare one for parts along with you I'd never want the dang things. Currently have 2 not running in camp as of this last fall due to simple contaminated fuel and we couldn't flush em enough. 2 days that we could have been doing other and they still didn't run by the time the flight arrived for us.

Of course YMMV.

A broken argo did some good for folks years ago. They stopped to snoop around an area they never hunted Argo broke an axle. While waiting they had nothing else to do. Unfortunately for us they have been hunting an area we have hunted for years, and bring more and more people every year. Thankfully most legal bulls are shot out now so the numbers are dwindling and less people show up.

But thats not at all why I won't go amphibious. Wrenched on too many

OP, it would be a neat and rewarding thing to do what you are proposing, but honestly the way I see it it is just a bridge too far.

My main concerns are the anchoring of course, tensioning the cables, the amount of sag it would have, and that the profile would seem to have to match the Elk Falls bridge in the video to be safe driving an ATV over it, as in some type of side rail enclosure.

As an alternative to the bridge, I really like the idea suggested previously of a storage shed on the far side for an ATV, and a stable jon boat to get across with what ever propulsion that makes the most sense. (Small outboard, oars, etc). Or a rope to pull on stretched across.
A short stairway also maybe to get up and down the 8 foot banks.

If the shed with the ATV on the other side is not feasible, then maybe two jon boats used as pontoons with a platform for the ATV and use a winch installed on it to get it up and down the banks.

I'm afraid with the cost of the bridge you may be money ahead by going on premier guided hunts and buying Kobe beef.

Good luck with your project.

PS, I have driven across the Powder River in my pickup also, but I'm sure this is a different time and place.

I haven't really thought about the pitfalls of this but I wonder if you maybe lay a cement path or build up a shallow area in some way so you could just drive across during normal water flow? as long as water could flow above it then it wouldn't hold the water back , but I don't remember if the OP mentioned the depth of the water. Anymore than 3 ft' and its probably not feasible anyways.

I know during flood stage you wouldn't be able to cross but that would still open it up about 90% of the year

Water in fall is only a foot deep, to two foot. But bottom is soft.

I previously posted the statute, but you can’t alter a stream even to put in riprap without a permit.

Late fall is icy, or chunky, fording it is not super safe.

I don’t relish a Jon boat at -degrees.

I am soft and believe that I can engineer a solution.

Can you dig out the bank to make a more reasonable approach? Putting all the soil on your lands of course

i would have to double check legality but I believe you have to have a permit to do any bank or stream work.

Getting a permit to do some stream work, maybe a culvert, would probably be easier and cheaper than a 200' suspension bridge...assuming they'd give you a permit.

Getting a permit to construct anything on land owned by your state or the Federal government is a mighty hurdle leap.

Something is telling me this land for sale the OP is thinking of buying might just be on one side of the river in question.

If so, and if a lease agreement could be obtained, the insurances involved would render the project cost prohibitive.

Ski resorts pay millions annually in lease fees alone to build towers to stretch cables between and those leases hindge on proper insurance being maintained.

I have acreage in Montana where crossing a moderate size creek on a 80ft long old rotting bridge on my own land is my sole access.

EPA is my demon, special creek protecting requirments to just remove and replace my bridge soared beyond $500K and that's not including the construction of a new bridge!

Probably be cheaper and easier to buy another 4-Wheeler and leave it on the other side of the river. Leave a Canoe of Kayak in the area to cross the river when you need to.

I've seen a 20' culvert.....but never a 200.

just turn your 20' culvert 90 degrees.

10’ culvert over the river would be enough to ride an atv through.
I guess with a cable stringer on top it might work?

Would weed out the trespassers using it...

That's how I always install them.

You would not be permitted to enter river and culvert would not survive river.

I had a crazy brainstorm solution to this problem last night while browsing the interweb for a cheap pontoon boat for a fishing trip this spring...

I see you can buy the replacement pontoons for all sizes of pontoon boats, docks, etc... you could get 10 or 15 of these for around $750 from Alibaba shipped to your door. Put a cable from shore to shore to anchor them across the river at regular intervals and put some type of planks or plywood drivable surface on top of them to get across. Set them up when you need them and take them out and store them away when they aren't in use in an on site storage unit of some sort.

Of course, this would require excavating a way to get down to river level at both ends, but I'm pretty sure that is doable as long as you don't impede or impact the stream itself ... and you would need to construct some sort of anchor points at both ends, but these wouldn't be nearly as substantial as a bridge abutment or anchor point...

Yeah, I know it's crazy but thinking outside the box can open up possibilities you may not find otherwise...

Bob

Yup...a 200' bridge is unfeasible for your purpose. A ferry is the way to go.

We built a bridge five years ago over the creek running through our property. Used two old steel square tube light poles with shaved down 6X6 slid in each end.
Worked for three years, could hold a quad and rider.
Couldn't stop the spring freshet.

You guys missing that he CANNOT drive through the waterway below high water mark? Legally.