South Fork log bridge- Mtbr.com
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  1. #1
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    South Fork log bridge

    Please do not add anything to the entrance to the bridge on South Fork.

    The log bridge was built with input from Thomasberg, the forest service engineer and myself. The ride up onto the bridge is intended to be hard, harder then actually riding across the bridge.

    I am the adopter of South Fork and have been maintaining this trail for 10 years. 4 or 5 times this season I have stopped and removed some jenky sticks that someone has piled up so the bridge is easier.

    Fellow trail shredders, COTA members and forum readers, please remove any attempt to make the ride on easier.

  2. #2
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    I don't understand the rationale for this type of bridge construction. I assume the difficult entrance is to dissuade mediocre riders from trying to ride the bridge, and then tumbling off it if they lose balance. Expert riders are assumed to be able to handle the step-up easily, and ride it safely. But the gray area is 'advanced' riders such as myself - we can ride it easily if the entrance is ramped or flat, but with the stepped entrance, I find myself in a scary 'no man's land' when I launch my bike over the step, not knowing how the variable physics of my approach will influence my trajectory. Once I make it past that tipping point entry in a straight line, then I'm good to go, but often I get deflected and barely eke out a safe crossing. I think ultimately a ramped entry would be safer for the majority of riders. Otherwise, make the step(s) extremely high, such as encountered on many bridges on the MRT.
    (btw I never do any 'mods' to such structures)

  3. #3
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    Anybody ride the North Fork bridge?

  4. #4
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    Quote Originally Posted by DirtSnake View Post
    I don't understand the rationale for this type of bridge construction. I assume the difficult entrance is to dissuade mediocre riders from trying to ride the bridge, and then tumbling off it if they lose balance. Expert riders are assumed to be able to handle the step-up easily, and ride it safely. But the gray area is 'advanced' riders such as myself - we can ride it easily if the entrance is ramped or flat, but with the stepped entrance, I find myself in a scary 'no man's land' when I launch my bike over the step, not knowing how the variable physics of my approach will influence my trajectory. Once I make it past that tipping point entry in a straight line, then I'm good to go, but often I get deflected and barely eke out a safe crossing. I think ultimately a ramped entry would be safer for the majority of riders. Otherwise, make the step(s) extremely high, such as encountered on many bridges on the MRT.
    (btw I never do any 'mods' to such structures)
    I think thats the point. If there is a ramp to lead you on, you assume you can do it, and if you loose it once on, that fall has some pretty good consequence. Maybe they want that bridge to be "expert only". My wife tumbled off that one a couple years ago, and she would not have tried it, if there was no ramp. Luckily she made it 3/4's of the way and jumped to the far side berm.
    Bend, Oregon

  5. #5
    Nat
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    Quote Originally Posted by DirtSnake View Post
    I don't understand the rationale for this type of bridge construction. I assume the difficult entrance is to dissuade mediocre riders from trying to ride the bridge, and then tumbling off it if they lose balance. Expert riders are assumed to be able to handle the step-up easily, and ride it safely. But the gray area is 'advanced' riders such as myself - we can ride it easily if the entrance is ramped or flat, but with the stepped entrance, I find myself in a scary 'no man's land' when I launch my bike over the step, not knowing how the variable physics of my approach will influence my trajectory. Once I make it past that tipping point entry in a straight line, then I'm good to go, but often I get deflected and barely eke out a safe crossing. I think ultimately a ramped entry would be safer for the majority of riders. Otherwise, make the step(s) extremely high, such as encountered on many bridges on the MRT.
    (btw I never do any 'mods' to such structures)
    Mark, put on your water wings and go for it!

    Get viddy too please.

  6. #6
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    I was there today.... there is a 2 x 6 (or larger) piece of wood, as a sort of "ramp".

  7. #7
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    Yup,
    making the entrance hard discourages any one from riding across who really shouldn't. I understand there are folks who could ride the bridge if the entrance was easier. The bridge is outside of FS engineering specs, so this was an attempt to force people to walk.

  8. #8
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    The bridge is outside of FS specs due to the lack of handrail. The size and span of the single log stringer is up to snuff. That being said, there are other examples of FS bridges that don't have handrails, some that have a rail on one side, and others that have full rails.

    Bridges over 20' in length require a FS engineer from the regional office to "sign off" on the design and bridges under 20' don not have that requirement.

    I was very involved in the build of the SF bridge a few years back, and as a professional trail contractor have built many a bridge on FS and other trails.

    I think it is a losing proposition to not have an entrance ramp onto this bridge. There was a plank when I rode SF over the weekend, and you can remove that today and another something (piled logs, or whatever) will appear again in less than a week.

    Being an expert in trail related risk management, I would suggest that a well built entrances ramp would have lower risk management issues as compared with the always present (in different formats) cobbled together makeshift approaches we see now.

    The idea behind the no approach ramp was born in a concept we refer to as trail filters or qualifiers. In many cases however, the qualify is much more difficult than the trail feature itself. This is the case with the SF bridge.


    Quote Originally Posted by wild1 View Post
    Yup,
    making the entrance hard discourages any one from riding across who really shouldn't. I understand there are folks who could ride the bridge if the entrance was easier. The bridge is outside of FS engineering specs, so this was an attempt to force people to walk.

  9. #9
    Nat
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    I was a fan of the old bridge design (wide and forgiving) before it rotted and got replaced by this new one (since I suck at riding skinnies and don't want to fall and break any more bones).

  10. #10
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    Anyone care to post a pic so we have an mental image of what you guys are talking about?

  11. #11
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    This pic was taken exactly 3 years ago. The bike on the other side lends a bit of scale to the picture ... well, sort of.
    Attached Thumbnails Attached Thumbnails South Fork log bridge-sf_log_bridge.jpg  


  12. #12
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    I'd argue this isn't so much a "filter" technique as it's a bandaid to allow us to keep riding the bridge that is outside of the FS spec.

    If we go the "proper ramp" route, the FS needs to get involved, and pretty soon that bridge gets torn out and replaced or there is a bunch of paperwork and red tape. Then guess what? FS doesn't have the funds to build it.

    So COTA ends up paying for it.

    Maybe someone needs to convince the FS to pay for it as it will be cheaper than the legal fees when someone breaks their neck? Then again, you get them involved and it may just go away for good.

    Not easy solution that I can see.

  13. #13
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    You need to stay healthy Nat, so you can take care of others broken bones (and other foot problems).

    Single log stringer bridges are common on FS trails, but more often found on hiking only trails. It was an interesting choice for a trail that is 95% mountain bike traffic.

    Quote Originally Posted by Nat View Post
    I was a fan of the old bridge design (wide and forgiving) before it rotted and got replaced by this new one (since I suck at riding skinnies and don't want to fall and break any more bones).

  14. #14
    Nat
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    Quote Originally Posted by Woodman View Post
    You need to stay healthy Nat, so you can take care of others broken bones (and other foot problems).
    Hear, hear.

  15. #15
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    Building on/off ramps is actually much easier than you may think (to get approval for). It is the long spans of bridges that are slow, but a ramp up and onto a bridge is not a big deal. I managed a project back in NC just before coming out here this year and the trail rebuild (road to trail conversion of over a mile of badly eroded old troad- road being used as a trail) included 2 FS bridge spec bridges. The planset we got from the FS engineer did not have any on/off ramps but they were badly needed due to the height of the decking after all the overkill materials (sills were 12"x12", stringers were 4"x14" read not fun to haul in or handle). We retro fitted the bridges and built on/off ramps with round poles for stringers and the same decking, no approval was needed and the local FS folks could not have been happier. Thier bridge design did not call for rails despite being 8' off the water on one side, but we added bull rails which they liked. You can read about the project and see the bridges in the video link at 3:50 and 6:00 using this link


    Pisgah Area SORBA Blog Archive Recap Lower Black Mountain ?Big Dig? 2014


    Quote Originally Posted by sketchbook View Post
    I'd argue this isn't so much a "filter" technique as it's a bandaid to allow us to keep riding the bridge that is outside of the FS spec.

    If we go the "proper ramp" route, the FS needs to get involved, and pretty soon that bridge gets torn out and replaced or there is a bunch of paperwork and red tape. Then guess what? FS doesn't have the funds to build it.

    So COTA ends up paying for it.

    Maybe someone needs to convince the FS to pay for it as it will be cheaper than the legal fees when someone breaks their neck? Then again, you get them involved and it may just go away for good.

    Not easy solution that I can see.

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