OT - Building a small bridge

4Runner

Have some hunting land with a creek that runs through the middle.  We want to build a bridge to cross the creek.  Span would be 10'.  Thinking 2x4 with a width of 2'.   Just want to walk back n forth so we would lay it down...almost like a ladder but crossing the the creek.  Not sure about the surface that you would walk on yet.   Any ideas or input welcome.  Thanks.  

GregW

I would use at least a 2x6 to keep it from feeling springy. Will it be a permanent installation? if not weight will be an issue.
A 5/4 thick deck board would be perfect for the walk boards.

4Runner

We plan to leave it there but didn't plan on securing it to the ground.  

GregW

That would work well. Be sure and screw the deck boards down. And I'm sure you will be using pressure treated lumber

4Runner

Yes.   I'm thinking now we need to go 12 feet across.  I'm going to find a crossing spot and measure.  Anyway, what should I use to build the surface?

Proser

2x8 would not be much more and if your hunting buddies are like mine it wouldn't hurt 

4Runner

What about 4x4's for the "frame" and then 2x6's for the walking surface.   Maybe 2.5' wide.  

GregW

If you are going 12 feet I would go up to a 2x10 and use 2x6 floor boards.
This will handle the 2.5 feet floor width.

4Runner

@GregW - 2x10.   I don't follow. Sorry, I'm an IT guy.  This bridge is going to suck.  Lol. 

Sea2Ski

You also have to consider peak run volume after a heavy downpour.  You could finish it beautifully, but have it all washed away after a small storm... Or big storm.  

fishlessman

did one for a wheel chair, 3 2x8 vertical with 2x 6 going flat across the 3 side to side

YukonRon

Sea2Ski said:

You also have to consider peak run volume after a heavy downpour.  You could finish it beautifully, but have it all washed away after a small storm... Or big storm.  

Totally agree! You really need to determine prv of the creek. Once you have that, you will have a much better idea on what to build. Built a span twice, built a bridge once, because I got tired of trying to find the spans after heavy rains. Found them, in pieces.

stemc33

Make a cool rope bridge. 

RiverRatSkier

Find an old aluminum extension ladder and keep it off to the side so you can put it across when you need it, and take it out when you don't.  If you need a deck, some green treated plywood would work fine.

4Runner

Good points.   Creek doesn't rise much at all and we control the flow via dam upstream.  Think I'm going to use 4x4 with 2x6 for the platform.   Going to look at the ladder angle too. Thanks 

tarheelmatt

With all the job titles that are thrown around here, someone has to be an engineer for Army Corp. of Engineers.  

DaveRichardson

I'd find 2 old railroad ties to use as anchors on the bank, then i'd use 2x8 minimum for the span.  Glue and screw the spreaders to make a ladder-like frame.  Cheapo decking will be fine for the surface.

DaveRichardson

check out this calculator.....
http://www.awc.org/calculators/span/...rcalcstyle.asp

I am assuming that since you are a Southern Gentleman, like a lot of us on here, Yellow Pine will be the timber of choice....  You might want to use 2 2x10 sistered together on each side to span that 12 foot length.

DoofusOfTheDay

I would never use 2x4 for span, at least 2x8 at that distance, and expect a little bounce.

SmokeyPitt

I'm also an IT guy so take this with a grain of salt, but you are basically you are building a deck across the creek so you might find some deck plans. As others pointed out you probably want to use taller board vertically (joists) for the framing that spans the creek.    

TexanOfTheNorth

This bridge option seems to be getting complicated. Have you considered a tunnel instead?

DoofusOfTheDay

TexanOfTheNorth said:

This bridge option seems to be getting complicated. Have you considered a tunnel instead?

Well if we're looking at other options...Rope Swing or zip-line.  

BigGreenGator

fishlessman

20 inch by 12 foot all aluminum
http://www.zoro.com/werner-two-person-scaffolding-stage-12-ft-l-2512/i/G7594867/?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&gclid=CIPN94yaksYCFc-PHwodKWUA1Q&gclsrc=aw.ds

Lit

I would do 3 board across vertical at a minimum 2" * 8" with 16" center to center desperation so about 15" separation. Spaced like that you should be fine with standard deck boards to walk on. You are going to want footers to keep the boards off the wet ground like in smokey pitta illustration. You can get premade concrete footers for cheap at Home Depot just put 3 of these on each side and put the boards in the slots and screw you one by 6's or 2 by 6's in. Should be a pretty easy project just need a saw and a drill. http://www.homedepot.com/p/Unbranded-10-in-x-10-in-x-8-in-Concrete-Deck-Block-012023A/205613606

BigGreenGator

fishlessman said:

20 inch by 12 foot all aluminum
http://www.zoro.com/werner-two-person-scaffolding-stage-12-ft-l-2512/i/G7594867/?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&gclid=CIPN94yaksYCFc-PHwodKWUA1Q&gclsrc=aw.ds

I just priced out doing a 24" wide x12' long pressure treated walkway came to just under 200.00 lumber and nails ... Seems to me @fishlessman is on to something if you just want a walkway and nothing else plus you save the labor  

MediumRarely

tarheelmatt said:

With all the job titles that are thrown around here, someone has to be an engineer for Army Corp. of Engineers.  

One of my degrees is in Nuclear Engineering, so I'll just put my $02M worth in here.  It should only take a single truck of concrete, but order 2 just in case - along with one ton of #5 rebar.....

Legume

https://www.jukinmedia.com/videos/view/1111

dlk7

Surespan makes really nice ones.  You did say you had plenty of cash - correct?

www.surespan.com/construction-services/bridge-construction/portable-temporary-bridges/

GregW

This is starting to make The Bridge on the River Kwai  look simple.
I've never had much luck bringing horses down to the water to make them drink, in fact I've drowned a few that way. They just won't drink. 

theyolksonyou