Author Topic: Suggestions on a simple footbridge over a brook?  (Read 6777 times)

Offline Going Galt

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Suggestions on a simple footbridge over a brook?
« on: December 07, 2009, 01:44:42 PM »
The following looks like a good place to put a footbridge across the brook on my land.  (Although I may want to run an ATV across it someday.)  This spot is good because of the log drag zone intersecting the brook, so that I can continue the path on the other side to the far side of the property.  Also, it is just 50 feet away from where I want to build a path to anyway (my future picnic spot by the brook).  As you can see, someone long ago had the same idea and laid 2 trees down here already (and they are slippery so I don't dare walk across).  Also, a couple of trees were washed down the stream and got caught up here when the water was higher.

I think a 12 foot plank would cross this now although just barely, but flash flooding will make the brook rise a foot or two and expand over a sizable area (maybe 20 to 30 feet).  Not very deep, but possibly quite wide.  I don't want whatever I put there to wash away.  A simple board laid there would wash away.  Any suggestions on a good way to hold it down, without looking tacky?  I'm wondering if I should put 4x4's down into the ground and nail it to it.  Or, maybe rely on the end supports of the planks being something heavy (short logs?  concrete blocks?)




Offline ncjeeper

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Re: Suggestions on a simple footbridge over a brook?
« Reply #1 on: December 07, 2009, 02:07:12 PM »
I have assisted the forest service in building log bridges at water crossings for 4wheel drives to go over. We used treated poles about a foot in diameter and laid them in the water in the direction of the water flow. Each end had a hole drilled in it and we would run cable thru them and anchor them at the base of a tree on each side. Of course these crossing were at places where the water wasnt very deep.

Offline Going Galt

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Re: Suggestions on a simple footbridge over a brook?
« Reply #2 on: December 07, 2009, 02:19:26 PM »
Sounds like a good solution.  Although, 12" wide poles like that would be too heavy for me to get them down there.  There isn't any way to drive to this spot (not even by ATV, at least until I have the path cleared).  Come to think of it, my vehicle wouldn't even get them to the land in the first place (small SUV).  Whatever I do, I'll need to do mostly with lumber.  (I wish I could get a pickup truck now but it'll be a while before I can afford it.)





Offline Orionblade

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Re: Suggestions on a simple footbridge over a brook?
« Reply #3 on: December 07, 2009, 02:28:02 PM »
A neighbor put an aluminum ramp salvaged from a Uhaul style truck across his ditch, and that seems to work pretty well for lawnmowers and the like.


Offline ncjeeper

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Re: Suggestions on a simple footbridge over a brook?
« Reply #4 on: December 07, 2009, 03:27:03 PM »
We would attach a couple of the poles to the back of a jeep and drag them to the location. I imagine an ATV would work also, but as you mentioned you you need to clear access to the creek first.

Offline longrifle

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Re: Suggestions on a simple footbridge over a brook?
« Reply #5 on: December 07, 2009, 03:31:49 PM »
Could you sink some concrete pillars into the ground in the creek and top them with some large river rocks making a low water crossing retaining a natural look?

longrifle

Offline Going Galt

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Re: Suggestions on a simple footbridge over a brook?
« Reply #6 on: December 07, 2009, 03:49:22 PM »
Hmmm.... rocks.  Maybe!  If I put rocks there, I think they'd stay fairly well put by themselves without having to put any concrete posts in.  They might displace a little.  The trick is finding rocks small enough that I can move, but still big enough that they'll work.  The land is rocky, so finding potential rocks should be easy.  I think I could use a pry bar to pull them out, then a hand truck to move them into position.  I need to move rocks anyway as part of my upcoming path clearing attempts.

Just checking, but you were suggesting packing the rocks tightly together, right?  i.e. not using them just as stepping stones with space between them?




Offline longrifle

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Re: Suggestions on a simple footbridge over a brook?
« Reply #7 on: December 07, 2009, 04:04:12 PM »
Galt,

I was thinking of a phased emplacement actually. If you have the bedrock to support just laying then down without any sort of foundation, then all the better. Personally, I would lay the larger stones first with gaps like stepping stones and then proceed to fill in between them later with smaller stones. That would allow the larger stones to settle into place better, giving you a footpath to cross the creek immediately. After they have settled on in, they will anchor the smaller stones and be less prone to washing away. I hope that helps or at least give you some ideas to chew on.

longrifle

Offline Who...me?

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Re: Suggestions on a simple footbridge over a brook?
« Reply #8 on: December 07, 2009, 04:27:42 PM »
Get some HDPE (high-density polyethylene) drainage pipe.  Use the double wall as it is MUCH stronger and the smooth interior promotes better water flow.   Use 36" or bigger diameter and cut down to whatever length you want.  Probably 6' would be wide enough to run ATVs over.   

Place a row of pipe sections across the brook (maybe 4 or 5 sections) so the water flows through the pipe. 

Now take a couple 2"x12" planks and lay them beside each other across the pipes for your foot path. Use some 2"x4" pieces for cleats to hold your planks together and sit in the space between pipe to keep it from sliding.

Take some 2"x4"s and pound them vertically into the creek bottom on either side of your pipe sections to keep them from pushing apart. You can also attach your planks to them to make it stronger.

When you get vehicle access you can make stone ramps with gravel and fill on top of the pipes with stone.  Cover the upstream side of your bridge with cabbage heads (rocks the size of your head) to prevent erosion.

Fred_47460

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Re: Suggestions on a simple footbridge over a brook?
« Reply #9 on: December 07, 2009, 04:42:57 PM »
Here is a link to a web page I found where they are building a bridge over a small creek. The beauty of this idea is that they use laminated 2 x 6 lumber for the support beams.....this means you could carry the individual 2 x 6 boards out to the site and glue (and bolt) them together on-site...thereby avoiding having to carry heavy beams out there.

http://www.ronhazelton.com/archives/howto/footbridge_over_creek.shtm

Offline cohutt

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Re: Suggestions on a simple footbridge over a brook?
« Reply #10 on: December 07, 2009, 05:53:31 PM »
i put in a couple similar to the design in Fred's link. i didn't bother to use any footings and it isn't a big deal. they have been moved in the past by flash flooding and hogs walking up the creek but are light enough to wrestle back in place.  tip: if you make them longer than you think you need them to be you have more options for firm footing and/or leveling.  if you are concerned it will wash away rope or cable it to a tree.

Offline Going Galt

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Re: Suggestions on a simple footbridge over a brook?
« Reply #11 on: December 07, 2009, 06:38:53 PM »
Will that one in Fred's link work if I need to span a distance that is longer than a typical board length?  I was wondering if there was a good way to fasten them together to make it long enough, without using a support in the middle.  Maybe not?  I'm only asking because my current car can't carry any boards longer than 8'... so that leaves out the 12' boards that I'd prefer to use.


Offline cohutt

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Re: Suggestions on a simple footbridge over a brook?
« Reply #12 on: December 07, 2009, 06:49:24 PM »
sure, you could peak it in the middle a bit and then add horizontal braces in the span under the bridge. it would look like a very wide but very short/flat "A" in profile.  4x4s for the span with 2x4s as the braces would work fine- the 2x4s would be to keep the span from flattening or collapsing.  if both ends of the bridge were butted into the bank it would assist in this.

Offline survivininct

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Re: Suggestions on a simple footbridge over a brook?
« Reply #13 on: December 07, 2009, 07:05:42 PM »
For a natural looking (and, more importantly, cheap ;D) little ATV and footbridge, take a few larger logs as long as you need your bridge to be wide, and place them parallel with the brook on the banks to make an embankment of sorts (you can even place two down beside each other and another on top making a triangle for more height), and some more longer logs perpendicular across them and the brook as carrying beams.  You can then either place smaller logs across the beams to make a deck, or you can go with planks.  The logs are great because they are heavy (will not move) and free!  Nail them all together with some large (8") spikes and or some cables or chains if the water really runs hard in times of heavy rains.  You can then make some entrance ramps on each side using some other logs, and bata bing, bata boom - instant cheap bridge! 

When if floods, go somewhere else to have your picnic   ;)

Offline Going Galt

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Re: Suggestions on a simple footbridge over a brook?
« Reply #14 on: December 07, 2009, 07:22:16 PM »
Come to think of it, I don't really need to have the bridge support an ATV... I just remembered that ATVs like to go through things like mud and small brooks.  I'll just drive through the brook.  So, foot traffic is the only issue.

So far, the rock idea sounds the best to me.  It doesn't require much skill, just some brute force.  I like that it looks more natural, in case any wetland nazis ever come for me for constructing a bridge in a wetland.  ("Hey, the rocks were like this when I got here.  Go ahead and carbon date them if you doubt me.")

Offline Going Galt

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Re: Suggestions on a simple footbridge over a brook?
« Reply #15 on: December 07, 2009, 07:34:05 PM »
Also, I don't mind walking across a single plank that is 12" wide, such as a 2x12 board... my goal is just to walk across and not get wet.  Is there a good way to fasten a board to a pre-made concrete form that I set on the ground on either side?  I guess I could just tie it (would work for a cinder block anyway), but was wondering if there is a better option.  Does pre-made concrete ever come with a built-in way to attach boards to it?


Offline cohutt

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Re: Suggestions on a simple footbridge over a brook?
« Reply #16 on: December 07, 2009, 07:48:17 PM »
cast your own with a lag bolt sticking out the top. you can use a duct tape reinforced usps flat rate box- the sides may bow but the top and bottom will be flat

Offline Pathfinder

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Re: Suggestions on a simple footbridge over a brook?
« Reply #17 on: December 07, 2009, 07:50:12 PM »
There is lumber that is much larger than 4x4 for bases on both sides of the stream. You can get 6x8 posts that can be cut to 5' lengths and laid on the ground to use as a base mount for both an access ramp and the joists/treads for the bridge.

6x8s come pressure treated too for ground contact. Just be careful, use a respirator when cutting them - a chainsaw is best.