Schematics for Wooden Features?- Mtbr.com
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  1. #1
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    Schematics for Wooden Features?

    Hey all,

    We are looking into adding our first wooden features to our local trails. Our land manager isn't opposed to using them, but he said we have to follow IMBA's guidelines so that he can be somewhat assured that the feature(s) will be safe. One of the guidelines recommends having a schematic design of the feature.

    Does anyone have an engineered schematic of a basic wooden ladder drop that they’d be willing to share with me? They say the schematic should show "scale, location, dimensions, materials, fasteners, filters, fall zones, signs, and optional lines." I realize this is a TON of detail, and will need to be customized to our specific trail. If we can just get a schematic that shows some of these, it'd be a good start.

    I’m working my way through some contacts at IMBA, and so far the only advice I’ve gotten is to buy one from "Progressive Bike Ramps." This is not what we're looking for. We have next to no budget, and we're doing this all with volunteer effort.

    I'm going to keep wading through IMBA folks and see what I come up with, but I figured I'd ask on here as well.

    Any help or other suggestions are greatly appreciated!

  2. #2
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    I can help you out with some of this stuff. PM me if you want. I think their requirements are excessive for a simple ladder drop. My guess is you can get away with some sketches and a Google Map plan view with scales and locations. Materials are usually whatever you have on hand. For it to really be engineered, you'd have to know the specific type of lumber you have. Let me know.

  3. #3
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    Following the load, material, and design guidelines for exterior decks as specified in your local building code is a good starting point. As far as I know, there are no standard drawings for trail features other than simple bridges.

  4. #4
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    About six years ago I designed a deck for a public park. I designed it to sustain a football team all standing neck and neck on the deck for a live load with something like 36 inches of snow for a dead load. You don't need that for a ladder drop on a bike trail. Building codes will work, but you'll probably be over building significantly.

  5. #5
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    It's preferable to overbuild the feature vs. save a few bucks in most cases. It will last longer, may even be less expensive in the long run, and will help protect you and the land manager in the, unlikely, event someone hurts themselves on it. The most likely reason the LM is asking for design specs. is because they are worried about liability exposure. Poorly built TTFs are a significant source of risk for all involved.

    There is a short section about TTF construction in the Whistler Trail Standards guide.
    Also: Squamish Trail Standards (pp. 16-19)

    A search of "TTF design standards" in Google will provide a bit more reading material but a lot of the results source the Whistler Standards guide.

  6. #6
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    +1 on the Whistler trail standards. I think they cover almost all of what you are asking for.

  7. #7
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    Both those documents offer great guidlines. Thanks for sharing them. If you still need something more specific to get approval, let me know.

  8. #8
    Tre1nt
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    IMBA used to offer web resources with resources for building wooden features but we decided to remove them because too many land managers and others were referencing them as construction "standards." Although this seems like a good service it's actually problematic for MTB groups because they can be held to such a standard in legal proceedings. We realized that the acceptable construction of wooden features varies a lot from location, weather conditions, intended use and other factors, so an IMBA standard was working against the interests of some local groups.

    The principles of trail design with rock and dirt can be generalized more easily -- although IMBA is still careful to say that our advice represents guidelines for trail construction and does not constitute a construction standard.

    One thing to consider is to check with your insurance provider about how much the policy and coverage would be effected with the addition of wooden features. The land manager may tell you that the features are okay because he/she believes that the liability rests with the group that does the construction. That may or may not be correct but it is probably worth figuring out ahead of time if that's still possible.

    It is quite possible to obtain coverage for trails with wooden features, but for some insurers it could trigger an increase in rates. The ideal situation is that the land manager signs off on the features and also bears most or all of the liability, and that this is clearly established in writing through a MOU or legal contract. If you do not already have such an agreement in place with the land manager now might be a good moment to consider creating one.

  9. #9
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    Can't IMBA ensure designs are soundly engineered? Without any standards at all, the burden is placed on the trail builder to bear liability and engineering costs. In a lawsuit where some kid is paralyzed for life because a structure failed, they'll have the structure analyzed to see why it failed. If the trail builder built it to an engineered standard then they have a reasonable defense, and the engineer who's name is on the design bears the liability. One of the reasons engineers charge what they do is because they are insured for that sort of thing. While I don't know for certain, I would imagine no standards anywhere just translates into nothing being allowed; the land manager and insurance companies like to limit their liability too. Is IMBA so poor that they can't hire an engineer to stamp anything?

  10. #10
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    It's not a matter of cost. If IMBA hired an engineer to create and stamp a construction standard for wooden features it would be super burly...which is great in theory, until you consider that many, if not most, of the existing wooden features that our chapters and affiliated clubs have built over the years would have to be brought up to that standard—otherwise they would be out of compliance and very vulnerable to lawsuits.

    We don't want to be in the position of hanging our own groups out to dry on this. The Whistler documents cited above seem to be doing a pretty good job of filling the gap.

  11. #11
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    I didn't consider that there may not be any grandfathering laws protecting the trail building community from being liable for existing features as there are in other construction fields.

    In roadwork, for example, standards are updated all the time and there is no legal responsibility to change anything in the field unless the owner is performing certain maintenance or construction activities that directly impact the out-of-compliance features. There is some guardrail in Utah that has been out of compliance for over twenty years, and as a safety feature very directly related to lawsuits if something bad happens. For signs, there is usually a compliance time frame wherein the owner is required to update things. Typically one of the reasons stamps have to have a date on them is so that they can't be used against anything prior to the date it was stamped.

    It is unfortunate that such is the current state of things for trail builders. For what it's worth, most of the bridges and wood features I've seen in pictures here appear to be quite overbuilt; a person on a bike is a very small load for any structure.

  12. #12
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    Actually, on this one, I'm going to agree with Mark E.

    The main thing a plaintiffs attorney needs to do is to show that there was a standard of care or design that was not followed.

    If there is no commonly accepted standard or design, then there is no obligation to follow it.

    It is actually a very bad idea for IMBA to set the standards for all TTF's for the world.


    The Four Basic Elements of Negligence

    •Presence of a Duty of Care. The first element is establishing the presence of a duty owed by one person to another. ...
    •Someone Breached Their Duty. The second element is a breach of the duty owed by one person to another. ...
    •The Breach Directly Causes Injuries. ...
    •Proving Monetary Losses.



    Our club got together and built rad TTF's. Our club bought insurance too. If the insurance company got it in their head that any particular organization set all relevant standards, that would be problematic.

    I like IMBA better when they're generally supporting clubs and the sport . . . not decreeing exactly how things have to be done.

    . . .
    Last edited by cmc4130; 05-18-2015 at 05:23 PM.

  13. #13
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    Which is why wooden structures simply aren't allowed in the vast majority of cases on public trails. Not following any standard at all is still negligence if someone gets hurt by poor construction. A structure built without any engineering standard still places liability on the builder. A defendant only needs to show that the standard was not in force, or even existed, when the structure was built to nullify the standard's applicability to a failed structure. That's why plans are dated and sealed.

    I'm not arguing with Mark, I'm just saying anyone scared of a lawsuit is just going to say no to anyone wanting to build something without an engineer's seal on it. So without common standards, a whole bunch of different trail builders have to fork over money to pay for engineering, which most people can't afford. So everything gets built without being designed and increases the real world probability of someone getting hurt.

    Accepted standards remove fear from building and construction in every industry they are applied. In the current world, without standards, most managers just say no. A plaintiff can't show a standard created today as negligence of a something built yesterday. I'm not responsible for the windows in my basement not meeting current building codes if a kid dies down there in a fire.

  14. #14
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    Okay, but there's a difference between whether a structure is physically sound, i.e. won't fall over, collapse under weight etc. versus whether it is *designed* with some standard of rider safety. In other words, an engineer could say that a structure is sound. But, some other "authority" might be cited as to whether it's safe for riders.

    We do not need a bicycle organization stating how tall drops can be, or how far back ladders can be from landings, etc. etc. etc. I would even be worried of some set of standards about what "green" "blues" "black" trails etc. have to be like.

    MTB should always be considered an inherently dangerous sport, where riders assume the risk of riding both natural and artificial features.

    Somehow, the skateboarding and skatepark building industry has managed to build hundreds if not thousands of public skateparks. A lot of them have features (like 10 foot deep bowls) which a layperson might see as inherently dangerous. But, somehow, it has worked out. Skatepark contractors have insurance. Yet, they're still allowed a lot of creativity to build things that are absolutely not guaranteed to be "safe" for skaters within the normal realm of what dangers are inherent in skateboarding.

  15. #15
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    The only safety standard I'm aware of is the helmet, and I don't think that's legally required on adults in most places. Trails don't have any safety features except intelligent grading and sight distances, and neither are standardized. Anyone using standard construction drawings to try to define safety is wasting their time unless the safety being defined is simply whether the thing failed or not.

    Risk is measured by actuaries who determine the probabilities of bad things happening and figure the insurance rates on the statistics. The "bad things happening" are only indirectly related to construction drawings if they are at all. It doesn't make much sense to me for people to try to determine safety from standard construction drawings at all, but I suppose it's not about "sense."

    To be sure I'm not casting myself in the wrong light, here is an example of an actual lawsuit that I'm aware of that somewhat applies to this discussion:

    There was once a school bus near Flagstaff Arizona whose driver fell asleep and wrecked. It hurt a bunch of kids. I believe a few died, but I don't remember the details. The school district offered to pay out something like $10,000,000 to the families of the kids in settlement. The kids families had a lawyer that decided that the state had more money so they sued the state for not having proper rumble strips (as shown on some standard drawings). The state ended up paying something like $100,000,000 to the families, the school paid nothing.

    Standards can cost a ton of money if they are defining safety features, but what safety features could be defined in the drawing of a wooden structure you're trying to use to add danger to the trail?

    I've ridden a handful of wooden features on public land, and a number of bigger features at the local lift serviced bike park. They can add a lot to a trail, I'd like to see more of them. I'm not saying IMBA should be the one to release standard drawings, but standard drawings from somewhere would probably be a nice tool to help get approval.

    For the OP, I believe some very simple drawings will probably work for what you're trying to get approved. I can help draw those up, or help teach you how to if you'd like. You'll have to ask what requirements are for the drawings from your land manager. The items you listed are mostly fairly simple and easy to put on a drawing. For the engineering, the wood and masonry construction code books I have are a good ten years old, but they should work fine for your purposes. I can't stamp anything for you as my work covers me with their insurance only for the things I do within the scope of my employment. Feel awesome that you're allowed to build them.

    EDIT:

    I just realized that IMBA can't really create standards because they are so closely involved in the construction of trails. They could easily be held to any drawings they create on any trail IMBA in any way is involved with building. IMBA is a poor choice as a standards organization unless they drop trail construction from their activities.

  16. #16
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    Sort of a ladder drop. Could you do something like making it out of a 3' rock and avoid some of these issues? Not the same but we try to incorporate natural features when possible. Build up rocks and dirt to lead up to the drop.

  17. #17
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    Ladder drop zone at Angel Fire NM bike park:
    https://vid1239.photobucket.com/albu...ps71b077a1.mp4



    Drop at Winter Park, Trestle Bike park. I think this might be No Quarter if I remember right.




    A natural terrain "drop" that our club did. It was essentially already there--it was just about making the top area flat and then creating a better landing zone.
    In action (yours truly)

    https://www.flickr.com/photos/374101...in/photostream


    Similarly . . . find a spot that already has a steep down-section, then add dirt at the top to make a flat area and add dirt at the bottom to make a landing area.





    https://forums.mtbr.com/trail-buildi...es-942628.html

    If you don't want to move a ton of dirt, and you have lots of available logs.... you can also do log piles with dirt in front and after.... I know this drawing is of table-top style features, but you could do something similar to make a raised area to ride on and then drop off of....


    pic from Keystone: (yes you can semi-cover logs with dirt)

  18. #18
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    Wow, thanks for all the helpful responses guys! You've given me a lot of food for thought. I'll make a list of points from this thread to discuss with my land manager.

    Coldfriction, I greatly appreciate the offer. Before I ask you to put effort into this, I want to have another discussion with our land manager and see if he's still okay to move forward with this. I'll get back to you.

  19. #19
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    Quote Originally Posted by Skelldify View Post
    Wow, thanks for all the helpful responses guys! You've given me a lot of food for thought. I'll make a list of points from this thread to discuss with my land manager.

    Coldfriction, I greatly appreciate the offer. Before I ask you to put effort into this, I want to have another discussion with our land manager and see if he's still okay to move forward with this. I'll get back to you.
    I know you need a schematic . . . but, even without that, it may help to compile a photo book of TTF's from bike parks around the country.

    I did that in a thread over here:
    TTF (Technical Trail Feature) / Freeride BUILD thread ---> inspiration

    Once you have the idea of what you're building, then maybe you could get a professional carpenter, or someone who can say "this will be structurally sound."

    Here's an example of a build day I worked on, where we created an "A-frame" type ladder obstacle. I based it off one at Keystone, but made it a little easier.
    Pace Bend . . . . opportunities - Page 7

    Austin Ridgeriders work:


    I based the design roughly on this feature at Keystone. The guys wanted it to be easier/less intimidating for xc riders, so I decided to mostly do away with the gap to clear.

  20. #20
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    Very cool stuff! Are there any places that have wooden features around Los Angeles? Besides big bear?

  21. #21
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    Got back from a trip to Highland MTB Park, New Hampshire.

    Wood feature small drop on Cat's Paw:


    Wood feature larger drop on Hellion:


    Another view of same drop on Hellion:


    Banked wall berm to drop on Power Hour:



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