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Burnaby, BC
Canada
667 Posts |
Posted - 05/22/2012 : 6:09 PM
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I hate it because it every time I have crossed that toothpick I have nearly shat my pants!
OK, so its the best place, I was just wondering. Perfect. pick a couple trees, rig them with ropes, tension them in the direction you want them to fall and make some precision cuts.
Thats how I would go about it, but hey. I could be totally wrong and off mark here. Just felt like sharing my ideas. |
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Vancouver, BC
Canada
874 Posts |
Posted - 05/22/2012 : 6:43 PM
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It can be a bit trickier than that. Factors to consider are: wind direction and speed, branches or other trees that may deflect the log while it falls, and the natural lean of the tree.
Also, falling big trees like that can be treacherous. I recommend reviewing the classic "Chainsaw and crosscut saw training course", published by the USDA Forrest Service and available from Lee Valley. |
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322 Posts |
Posted - 05/22/2012 : 10:26 PM
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quote:
Originally posted by Stoked
Does anyone know how much a 30-foot 6x18 Douglas Fir stringer weighs? Or 6x22 Hem-Firm?
If I understand you correctly, you want to know what a 30 foot long, 6 by 18 inch Doug Fir plank weighs, and also a 30 foot long, 6 x 22 inch western hemlock plank. Why aren't you using metric units: a 9 m long, 15 x 46 cm cedar plank or a 9 m long, 15 x 56 cm western hemlock plank.
Douglas Fir has a density of about 512 kg/m3, western hemlock a density of 432 kg/m3 (Source: http://www.csudh.edu/oliver/chemdata/woods.htm ) Remember, wood floats, so is always less dense than water.
So your Douglas Fir plank would weigh 512 x 9 x 0.15 x 0.46 = 318 kg, or about 700 pounds.
and your Western Hemlock plank would weigh 432 x 9 x 0.15 x 0.56 = 327 kg, or about 720 pounds.
I would not bother with planks- use two local logs (fir or cedar; don't use hemlock) with an average diameter of at least 30 cm, and pull them into place with a come-a-long and lift them with a screw jack (I have both if you want to borrow them). You might want to think about doing this when there is still frozen snow on the ground, and you can move the logs into position more easily.
Place the log stringers on abutments made of rock, or a small cedar log crib filled with rocks. To establish how high the abutments should be, measure the distance from the bottom of the creek bed up to where you think the high water would rise to in an average year (use a tape measure; don't guess), and then multiply this depth by 3. Your abutments should also be outside of the wetted perimeter; that is beyond any sand or gravel deposits left on the sides of the creek.
By my calculations, each log should weigh about 512 x 9 x 3.14 x 0.15 x 0.15 = 326 kg, or 718 pounds. |
Edited by - FrankB on 05/22/2012 10:58 PM |
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322 Posts |
Posted - 05/22/2012 : 11:03 PM
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| Once the logs are in-place, you need to lash them together (ideally, with cable), place thin saplings in-between the two logs, and cover this with sand to make a nice walking path. Add a couple of hand lines to complete the bridge. |
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964 Posts |
Posted - 05/23/2012 : 05:49 AM
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quote:
Originally posted by FrankB
[quote]Originally posted by Stoked
[b]Why aren't you using metric units: a 9 m long, 15 x 46 cm cedar plank or a 9 m long, 15 x 56 cm western hemlock plank.
Thanks Frank.
I was using Imperial units from U.S. publications.
Thanks for the offer of the jack and come-along. I think we'll need to take you up on that. I'd also thought about using the snow to reduce friction. We'd have to do it soon if we do. |
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322 Posts |
Posted - 05/23/2012 : 07:22 AM
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| Would be interested if I can spare the time; email me. |
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964 Posts |
Posted - 06/29/2012 : 09:43 AM
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| WeedWhacker, I saw on the trail to Hat Hilton that you used rock bolts to secure a rope. Have you got access to a rock drill? Just wondering how long it takes to drill a hole and place a bolt. |
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964 Posts |
Posted - 06/29/2012 : 09:47 AM
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We're applying for some funding from a couple of sources. BCMC has committed some and FMCBC has a fund I just heard about.
I was hoping to get up for another site visit in June but the weather has just been atrocious. Just about every weekend rained out.
I'm holding out for better weather in July and hopefully get this project rolling. |
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Vancouver, BC
Canada
874 Posts |
Posted - 06/29/2012 : 10:25 AM
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quote:
Originally posted by Stoked
WeedWhacker, I saw on the trail to Hat Hilton that you used rock bolts to secure a rope. Have you got access to a rock drill? Just wondering how long it takes to drill a hole and place a bolt.
I used a handheld hammer and drill. It took about 30-40 minutes per hole. I used 3/8" wedge bolts because they last a long time. It is much faster to place 1/4" bolts but they weather out faster. You can buy the drill, bolts, and hangers at MEC.
Or you can borrow mine if you like. |
Edited by - weedWhacker on 06/29/2012 11:05 AM |
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Snow load/footbridge replacement
