# Safety margin on sides of trail



## JonathanGennick (Sep 15, 2006)

When doing maintenance, especially when clearing downed trees, how wide a margin do you keep clear on either side of the track? Does IMBA have any guidelines?

I realize mountain-biking is inherently dangerous, but it's one thing to accept the natural hazards and quite another to increase the risk by leaving branches and limbs that can impale a rider who falls, or that protrude enough to catch a tire of an inexperienced rider.


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## bsieb (Aug 23, 2003)

We instruct our crews to trim back at least 24" from the center of the tread and at least 84" high


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## JonathanGennick (Sep 15, 2006)

bsieb said:


> We instruct our crews to trim back at least 24" from the center of the tread and at least 84" high


Thanks! It helps to know what others are doing, what sort of guidelines are in place.

Does anyone out there give thought to a rider crashing or falling, and attempt to cut back far enough to allow enough space to crash in without hitting a log, or cut up pieces of log, or brush that's just been tossed aside?


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## swampboy62 (Feb 10, 2009)

Yes, there are guidelines for this.

The IMBA "Building Better Trails":

http://www.wnymba.org/static/report/trail_manual/BBT_Manual.pdf

says:

The trail corridor should be at least twice as wide as the tread width.

And:

Put cut trees and branches at least 10 feet from the corridor. Lay them
with the butt end pointing away.

The Whistler Trail Standards guide talks about the "fall zone" - the off trail area surrounding trail features or difficult sections of trail. They suggest clearing hazards 1.5 meters on each side of the trail if there's some trail feature that could lead to a fall.

The USFS Trail Construction & Maintenance notebook suggests that a hiking corridor should be 6 ft wide by 8 ft tall.

Hope this helps.

Steve Z


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## JonathanGennick (Sep 15, 2006)

swampboy62 said:


> Put cut trees and branches at least 10 feet from the corridor. Lay them with the butt end pointing away.


Yes! This is the sort of thing I'm looking for. Thank you(!) for the pointer. I'll do some reading, and then probably some advocating.


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## Loren_ (Dec 3, 2006)

If a large log is down across the trail, we often just cut a narrow opening of 24 inches or so, but we'll trim off protruding branches, etc. so it's not a fall hazard. This adds a little visual focus point for riders, and enough of these makes the trail less attractive to ATVs and other misuse.


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## JonathanGennick (Sep 15, 2006)

What about branches at face-level?


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## mtbikernc69 (Mar 23, 2004)

If someone cuts down fall and it protrudes enough that someone is injured by it, then they are liable for that injury. My rule of thumb is to cut back pretty heavily in our area. We have an invasive species that grows like crazy in the late Spring. This usually keeps the corridor clear for 2 years with a little touch up every year. I tend to cut back to the width of the trail (usually 18"-24"). More on the inside of turns and less on the outside of turns. I don't like nor leave stuff at eye level as that poses a hazard that would either cause someone to crash and/or be injured in the face. Eye injuries suck!

Sounds like some education in safety and liability may be in order for some of your compatriots! Is this an organized club that is doing the maintenance? Sounds like they're not taking the liability we assume for building trails very seriously. All it takes is one accident, one lawyer and one judge. 

Ask Woody Keen. He can tell ya.


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## JonathanGennick (Sep 15, 2006)

mtbikernc69 said:


> Sounds like some education in safety and liability may be in order for some of your compatriots!


Well, that's kind of my goal, not just for them, but for myself as well.

I do have both IMBA books. One of them has a section on liability. I had forgotten about it, but your post brought it to mind. I'm going to reread that chapter.

Of the three of us who actually do trail work, I'm the only one who brings kids riding, both my own and various of their friends. That is a scary responsibility to be honest, and it probably colors the way I look at trail design. It's probably why I spend so much time asking myself the questions: "Could this cause a crash?" and "What if someone crashes here?".


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## bweide (Dec 27, 2004)

Proper prunning technique says the branches should be trimmed by to the Y. Branches head and body high I cut way back. Ground level stuff I cut off close to the tread.


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## KAriadne (Sep 14, 2011)

Loren_ said:


> If a large log is down across the trail, we often just cut a narrow opening of 24 inches or so, but we'll trim off protruding branches, etc. so it's not a fall hazard. This adds a little visual focus point for riders, and enough of these makes the trail less attractive to ATVs and other misuse.


As a rider, I like this. Trim the punji stick and slap to the face stuff back pretty far, but leave the large diameter "safe" stuff for visual interest and skill focus.


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## JonathanGennick (Sep 15, 2006)

*This thread is useless without photos*

Well, I rode some of the trail again today, and am thinking perhaps I worry too much. I did take some photos though. The first three are photos from years gone by, and represent Forest Service work. The fourth is from recent work.

#1. Cut back log near trail in the runout after the bottom of a small hill. I'm usually cruising pretty fast at this point. I would have cut that much further back.









#2. Log cut up and pieces just left by the side of the trail. Not at bottom of any hill though, so maybe no big deal.









#3. That stick protruding by my bicycle handlebar? That was sawed off at that location. It's a foot or so off to the side of the trail and a touch above handlebar height. I don't like it.









#4. Here's one showing a downed tree we cleared up the other day.


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## Fattirewilly (Dec 10, 2001)

JonathanGennick said:


> Well, I rode some of the trail again today, and am thinking perhaps I worry too much. I did take some photos though. The first three are photos from years gone by, and represent Forest Service work. The fourth is from recent work.
> 
> #1. Cut back log near trail in the runout after the bottom of a small hill. I'm usually cruising pretty fast at this point. I would have cut that much further back.
> 
> ...


1) Leave it if it doesn't have any pungie sticks creating fall hazards. It's okay to have a "choke" like this here and there along the tread to help keep things narrow or to make the tread meander. Also, half on half off the tread could work if its a situation where people like going over the log and removing that log will make folks complain about dumbing down the trail. Plenty of room it looks like for a more technical alternate line over the log

2) Logs should not be left parallel to the tread. That catches water, prevents drainage and can cause a mud hole to form. Stuff like that should be far enough off the trail to not cause an eyesore.

3) That's dangerous and should be cut much further back. We have beavers leaving spikes, broken off Pine branches, and other items you don't want to fall on which are created naturally. If I'm going past something like that with a saw, I'll cut those natural hazards too.

4) another example of a parallel log to the tread. At a minimum, flip it perpendicular. It would look better cleared back 10 feet or so off the trail


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## bsieb (Aug 23, 2003)

We require that slash be hidden from sight, bigger stuff pulled perpendicular far enough to not be a distraction to the rider. While your examples don't look hazardous to me, they do look sloppy to my eye. Since you have a better eye than the clods (  ) you work with, maybe you could put the finishing touches on, carry a small folding pruning saw for this purpose.


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## Ridnparadise (Dec 14, 2007)

Trimming 24 inches either side may work in some places, but it's an outdated and inflexible rule IMO. In some places it creates a very green and soft feel, but perhaps only on tight and low speed trail.









Add speed and riders lose perspective, the ability to see and prepare for what is coming, misjudge lines and create new lines that may damage trail edges, risk injury with oncoming traffic and in the end they just snap everything off that bothers them.

There is no global trimming rule. Trimming should be appropriate to the site and the character of the trail. If you can see ahead it allows very technical features like rock outcrops to be enjoyed by more riders and leads to a narrower trail tread being created by the users. Counter-intuitive it may seem, but wider trimming often = narrower trail.

Spot the difference - this trail has been trimmed up to 3m away from the trail edge, but it's not obvious unless you are riding it. Even then the only awareness is "wow I rode well today".

















Tossing trimmings wide from the trail makes total sense. Everyone loves a neat and pretty trail. However, logs along the trail edge is not the same thing. Sorry IMBA, but again there is no golden rule.

If a log lies parallel to the trail on a steep sideslope and is embedded in a trench, supported below by rock armouring if needed (ie rocks embedded below the log) and coated on the trail edge with stones, it will catch silt, harden the trail and build a new and wider/more stable tread over time. That is not bad, it is good.









In other places logs can be used as sight-lines









and sometimes they need to be above the level of the tread to let water flow under and avoid organic matter building up and creating slop.

Again this may not be a universal rule, but: 
If the tread is stoney and scoured by moving water, a parallel log on the downslope edge (placed as above) can help smooth the trail. If the trail is soft and smooth a downslope parallel log will destroy the trail.

Also, the pointed ends of those logs must not be an injury risk. Nor should any stabbing risk from fallen timber be left near the trail. That may mean it is moved 3m away from the trail in some places, but 10 or more metres away in others, like on the outside of a fast corner.

Nothing should be a risk at eyeline or distract the eye from the trail.

















That may include new shoots or other foliage that puts riders off their trail concentration.

Some of this can be confusing, like when you have a few tight saplings supporting the trail edges through bends. Sometimes they guide the rider and sometimes they make riders tense and prone to error. Removing one trunk at ground level when it impinges on the inside of a corner (while leaving the root system) may allow another few trees to grow without riders smashing them down.

Then there is the issue of trimming allowing more light getting through and new opportunists invading the trail etc etc etc.

I guess it's just a learning process and the learning keeps on keeping on because you never get the luxury of stopping work on it.


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## crank1979 (Feb 3, 2006)

Like Ridnparadise's pictures above show, singletrack in Australia seems much narrower than we see in the videos and pictures of singletrack running through trees and bush overseas. It's actually a comparison I've been thinking about more and more. I think over here we are starting to get a few wider style singletrack trails with the introduction of the 'flow trails' being developed.


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## JonathanGennick (Sep 15, 2006)

@Rideinparadise, thanks for posting those. Instructive. Your trimming6 and trimming7 photos hit me hard. It looks a lot tidier with that one branch trimmed back to the tree trunk instead of protruding out like it does in the first photo.


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## JonathanGennick (Sep 15, 2006)

*More Pics. Yay!*

One more batch-o-photos. I still have situations that are question-marks. I'll continue my previous numbering from where I left off.

#5. Here is an interesting case. The Forest Service volunteer who cut this log last year did the best she could, but left it protruding about 10-12 feet more than you see in the photo. (Sorry for lack of a "before" shot). There is a slight uphill and bend in the trail as you approach the log, and the log trends upward too, so as you came around you had to dodge this log sticking up and out towards you. The uphill part meant you probably weren't going fast, but a younger rider with stronger legs could maybe carry some speed. The protrusion annoyed me.

I was out with a different volunteer this spring. I convinced him to lop off about 10-12 feet. I would have preferred to remove the whole log. I still find it distracting and untidy. His saw though, so not much I could do about it when he decided it was good.

Remove the rest of the log? Or leave it as is? That's the question. Seems like a visual distraction, and I would happily go and help remove it.









#6. Here is a Forest Service cut from a few years ago. I see that log and think: "What if someone falls on it." Am I obsessing? I would cut that much further back and get it completely out of the way. Am I wrong to want to do that?









#7. These I will stop and drag off to the side on one of my next rides. Not sure who made the cut, but it seems lazy to just them like that as OTB hazards. All I need is for some kid to stray six inches off the track at that point, and wham! Maybe I'm wrong-headed, but I don't see the need to leave debris like that.









#8. Here is a recent cut I helped with on the weekend. I am thinking we should go back and clean up the cut pieces of log. I would prefer to cut that log on the right much further back. I lobbied for doing so when I was out helping, but again, not my saw so I did not prevail.

As for tidying up, I can't lift those large chunks. (Back trouble--I don't dare even try). Someone who owns a saw will need to cut them smaller before I can move them.









#9. Same spot as #8, but from the reverse direction. Trail is bidirectional. Most of us ride it most of the time in the #8 direction, but sometimes we turn things around for variety.









I did have a fruitful chat yesterday with the other volunteer who owns the saw. He and I will go back out to tidy up our recent work. I will probably show him this thread too, because the photos and comments from more experienced builders are instructive.


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## rebel1916 (Sep 16, 2006)

Not trying to be a ball breaker, but I would much prefer 6,7, and 8 to be closer to center of the corridor. I would definitely not have cut 7. What about leaving some logs across the trail and maybe building them up with stones to proved a little diversity in the flow?


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## Cormac (Aug 6, 2011)

wow, I need to take some clippers to my nearest trail. There are more than a few places where I need to duck to avoid getting a faceful of branches. I don't worry to much about the sides of the trail, just places where you might get your head taken off.


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## bsieb (Aug 23, 2003)

rebel1916 said:


> Not trying to be a ball breaker, but I would much prefer 6,7, and 8 to be closer to center of the corridor. I would definitely not have cut 7. What about leaving some logs across the trail and maybe building them up with stones to proved a little diversity in the flow?


Fail

For so many reasons... no offence intended. 

Why ruin the flow with distractions and artificial obstacles?


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## rebel1916 (Sep 16, 2006)

Fallen logs are the definition of natural obstacles. I did offer a way to make them easy to get over so lesser skilled riders could ride with their flow unimpeded. I prefer a narrower foot print as well. I am more of a flow guy than a tech guy, but trails need some tech. Even easy ones, or people never gin new skills.


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## JonathanGennick (Sep 15, 2006)

rebel1916 said:


> Fallen logs are the definition of natural obstacles. I did offer a way to make them easy to get over so lesser skilled riders could ride with their flow unimpeded. I prefer a narrower foot print as well. I am more of a flow guy than a tech guy, but trails need some tech. Even easy ones, or people never gin new skills.


Adding obstacles is a non-starter in this case. They are not in the Forest Service's plans for that particular trail. It's a combined hiking/biking (and horses are technically allowed as well, I believe). There is no support for adding obstacles like logovers. Would be fun to have some, but those will have to go onto some future, bike-specific trail.


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## bsieb (Aug 23, 2003)

rebel1916 said:


> Fallen logs are the definition of natural obstacles. I did offer a way to make them easy to get over so lesser skilled riders could ride with their flow unimpeded. I prefer a narrower foot print as well. I am more of a flow guy than a tech guy, but trails need some tech. Even easy ones, or people never gin new skills.


Ok, I'll buy that. With the amount of deadfall on my system it would have zero flow in a few years if we didn't cut it out at least annually. I see most of it as interfering with the trail as designed but am willing to accommodate it on occasion if it is too big to handle or is serendipitous. Speed and flow are assets too and must be maintained as well.

I try to foster a sense of wonder for the beautiful garden we sculpt in my crews so appearance is very important. Some of our YCC crews are actually lead by young landscape architects looking to get some real world trail expertise. We would typically use stone for any permanent infrastructure features. I suspect we are each dealing with different environments.


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## Visicypher (Aug 5, 2004)

Jonathan - clearing and corridor clearance specs are provided to us by the USFS district office under our challenge cost share agreement. As other have pointed, specs change from place to place. What works in one area won't in other.


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## anthony.delorenzo (Aug 17, 2006)

Safety is one thing but to my eye, seeing all those cut log ends is an eyesore. For that reason alone I would cut those out. Each to their own, of course. 

Something else to consider: Those cut sections that are hanging up on their lower limbs create a greater wildfire hazard as they dry out. We would buck and limb that stuff to get it down to ground level and avoid creating ladder fuels.


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## Skookum (Jan 17, 2005)

JonathanGennick said:


> I realize mountain-biking is inherently dangerous, but it's one thing to accept the natural hazards and quite another to increase the risk by leaving branches and limbs that can impale a rider who falls, or that protrude enough to catch a tire of an inexperienced rider.


Out of all the photos you offer, i see absolutely none that would qualify as a true hazard.

You bring up a valid topic, there are some examples of trail work that i've seen that create riding hazards. Usually on rogue built trail. Two examples that come to mind are one to two inch saplings angle cut off to the side, as well as open borrow pits literally off the side of the trail after it was used to create a berm.

If you show photos showing a trail where there is more natural or even man-made technical features provided, there may be more cause to cleaning up to provide for safe fall zones in mitigating any hazard. But your photos for the most part really don't provide such a definitive example of that. The trail itself is pretty straight forward, the likelihood of anyone falling in the areas you photo are slim to none.

The one thing i do see and can agree with you is most are examples of insufficient trail clearing. Looks like the trail you show is one where there is a pretty wide corridor to start out with. To leave deadfall/blowdown so close to intrude on the trail doesn't do anything to enhance the experience, i can see how many including yourself would liken it to seeing it as "cluttered". But i stop short of introducing safety as a reason to clean up the lumber here.

There are valid times to look at safety and how decisions are made during trail building and trail maintenance. In the case of your trail, my assumption is the trail corridor is so wide that people are running at a pretty good clip of speed. So my safety concern would be examining sight lines, making sure blind corners are taken care of. That would be something i would be more on the watch for as a trail steward on this particular trail. And even then we're talking lower priority details that can be ironed out with work.

So i would personally vote in favor of cleaning the trail a bit better with the pictures provided. But equating that trail work with a safety hazard, it's not there.


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## deezler (Jun 21, 2011)

A trail trimming thread with no comments about elbows-out in Sedona? Really? 

Those pics make me think my local trails are horribly over grown. I for one kind of like to ride on intimate, narrow trails (provided they are not in a high-speed section). The ones I am cutting on my own property now are really tight.. but they will expand over time.

I don't know how you could possibly get rid of all fall-hazards within 3+ meters of a trail. People can fall anywhere... and hit random things on their way down. It's a standard, accepted hazard of riding a mountain bike trail, right? I mean, is someone going to sweep every trail every morning to get rid of every possible pokey bit? Of course not.

The cut logs pictured here are certainly ugly to look at. That unsightly mess would personally distract me from "flow" more than a small log to bunny hop. If a log is over a foot in diameter... it's fun to ride through the cut channel. If they are smaller, either make a log pile, or get them the heck out of there. Just my opinion.

Multi-use trails... well... that sucks. haha.


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## Ridnparadise (Dec 14, 2007)

deezler said:


> A trail trimming thread with no comments about elbows-out in Sedona? Really?
> 
> Those pics make me think my local trails are horribly over grown. I for one kind of like to ride on intimate, narrow trails (provided they are not in a high-speed section). The ones I am cutting on my own property now are really tight.. but they will expand over time.
> 
> Multi-use trails... well... that sucks. haha.


Elbows out - my favourite.

BTW - really tight will not expand over time like humans. Trail becomes narrower, not wider. The less that ride, the narrower.


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## JonathanGennick (Sep 15, 2006)

Ridnparadise said:


> BTW - really tight will not expand over time like humans.


:lol: :lol: :lol:

As one currently fighting that battle, thank you for making me laugh and spew my morning coffee all over my keyboard. :thumbsup:


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## deezler (Jun 21, 2011)

Ridnparadise said:


> Elbows out - my favourite.
> 
> BTW - really tight will not expand over time like humans. Trail becomes narrower, not wider. The less that ride, the narrower.


Haha, yes, of course. I meant that I would expand them over time myself... not that it would happen naturally.


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