# cheap to build bridge to access woodlot ?



## Mainely Saws (Oct 16, 2010)

Hello folks ,
Sorry if I'm in the wrong forum for this question but wasn't sure where to post it . I need to gain access across a small creek to get into my woodlot . The span is about 1 across with a max. dept of about 6' . It used to have 2 15" culverts but they would always plug up when I wasn't there for a period of time & wash out . I have a 2000# tractor pulling a 4' x 8' trailor with a 1500# axle to load with firewood to cross this bridge . I've heard of folks cutting down & using a mobile home chasis but they are not very strong unless braced well . I was thinking of trying to find used utility poles , laying them down & screwing 2x6 PT decking over them or trying to find an old tractor trailor flat bed & laying it down to span the creek . Any ideas on a low cost way to bridge the creek that would last for a while would sure be appreciated .

Thanks ,
Bob


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## Backwoods Savage (Oct 16, 2010)

On the utility poles it might depend on what they have. Some utility poles are not that big and I'd hate to build something and fall through with a load on. Been there; done that.

Why not just make your own with the trees you already have? Then lay your  2x  decking on that. You also can lay more than 2 poles; double them up. It is cheap but you may have to replace the poles after maybe 10 years or more.


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## JustWood (Oct 17, 2010)

semi trailer


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## golfandwoodnut (Oct 17, 2010)

I always think culverts are better.  Why not get a larger diameter one that would not clog as easily.  They are cheaper than trailers, probably a couple hundred, you only need a 10 foot wide one.  To me dirt and gravel are cheap to put over it and if done properly could last for decades.  A bridge would be cool but more issues.


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## wolfram (Oct 17, 2010)

Looks like there is a typo in the value for the span.  Please tell us the correct span.  

In addition, please tell us something about the soil/banks and what you are willing to do for abutments.


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## Mainely Saws (Oct 17, 2010)

the span is about 16 ft across & on one side of the creek is a large boulder in the side of the bank . The soil is mostly gravel left over from previous repairs to washed out culverts . I did price a 20 ft. black PVC culvert ( 36" ) last year but the culvert alone was in the $600 range plus I'd need to pay for fill & someone to deliver the culvert , drop it in & dump the fill over it . All together it was going to be in the $2000 range . I've seen some used semi truck flat beds for under a $1000 .......


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## DanCorcoran (Oct 17, 2010)

Culvert will channel the water past the bridge.  Just about anything else will obstruct the water, and water always wins, sooner or later.


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## savageactor7 (Oct 17, 2010)

I'd locate a suitably graded approach, excavate it down to hard pan, back fill with suitable riprap, now you have a drivable underwater bridge. Made one threw our swamp that way but didn't have a 6' bank. Now life is good for us log draggers


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## wolfram (Oct 18, 2010)

Thank you for the additional info.  The US Forest Products Laboratory's Wood Handbook has equations that can be used for a log bridge with decking.  

I built a simple log bridge for a 24 foot span.  I used two treated utility poles with 15" diameter at the small end and placed them under the tire treads.  2" x 10" (full dimension) rough sawn softwood decking.  The decking is undersized and I should have used at least one more utility pole in the center.  I'm careful where I drive.  Deflection is less than an inch at a total live load of approx 3,500 pounds (communicated to the bridge through the four tractor tires).   Abutments are nothing special and that is a weak point of this bridge.  I used gravel for the two approaches.  The decking on this bridge will rot sooner than later....

Used poles, in excellent condition, cost me $100 total for the two.  Decking was $225.  Galvanized pole barn spikes, $25 or so.

I am not a civil engineer and do not give engineering advice.  YMMV.


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## Mainely Saws (Oct 18, 2010)

My concern with a culvert or riprap with a flow throw design is that in the Spring this little creek can have a fair amount of water running through it & it's in a heavily wooded area that constantly has branches & leaves falling into the creek . I'm not at the woodlot during the early Spring & cab't keep an eye on it to clear out the debris so that it won't wash out the road . I like the idea of the utility poles & decking , then the creek can do what it wants without washing out . The creek has been freeflowing without culverts for about 6 years now so the old roadbed is pretty much gone . Thanks again for the info & suggestions ........


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## CountryBoy19 (Oct 18, 2010)

savageactor7 said:
			
		

> I'd locate a suitably graded approach, excavate it down to hard pan, back fill with suitable riprap, now you have a drivable underwater bridge. Made one threw our swamp that way but didn't have a 6' bank. Now life is good for us log draggers



Be careful doing this, in many states you need special permits (yes, even on private property) to make a drive-through stream crossing. Not getting the proper permits can get you in a lot of trouble and cost a lot of money, especially if it has been determined that driving through the stream somehow contaminated it. I would advised against doing this if at all possible. The only time I've seen this as a practical method is if you have a really wide, shallow stream where a bridge is just going to be too costly.

My dad is a drainage contractor, he knows the ins and outs of a lot of that stuff and it's rubbed off on me a little.


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## firefighterjake (Oct 19, 2010)

We (Snowmobile and ATV Clubs) build bridges all the time . . . and most of these bridges are designed to carry the weight of pretty heavy equipment (typically the weight of a groomer -- a Ford Ranger, snow drag and of course the weight of the snow) . . . most of the time we've used old telephone poles (or similarly sized cedar trees) as stringers for a distance that you've mentioned.


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