![Switchbacks at Zion National Park. [Wandrin_006-2.jpg 24 KB]](Wandrin_006-2.jpg)
Two BIG tips:
¤ Adopt a trail: Find a trail that you like, and study it. It should be not too long, fairly heavily used, and with a variety of conditions and potential problems. And close enough to home that you can get to it frequently (at least ten times a year), especially those times when you don't have a whole day available. Then do this for five to eight years. The purpose is not to fix the trail, but to get to know it, and watch how it evolves over a long period. Much of what we are taught about maintaining trail is just hoary mythology, where we are told what causes various problems, and told what fixes them. But is that correct? You should observe for your self.
Do this for several years and you may come to the biggest tip of them all:
¤ Respect grade: This is the core principal of building switchbacks. If you do not respect grade your work is inherently faulty, and the tips in this section for building better trail are pointless.
Two other key points:
¤ Rise over run: This is the key concept in building switchbacks. Grade can be measured, and even conceptualized, in various ways, but "rise over run" is so perfect for our needs that it would be an error to use any other method. We nearly always have a fixed challenge to meet (the rise) and a limit (the maximum grade); the variable under our control is how much run we can fit in. "Rise over run" is not just a useful definition of grade, it is the way to think of grade, and of grade problems.
¤ Measure it! If you don't measure grade you're just guessing, and most likely overly optimistic. Without definite measurements it is too easy to slack off and slip into substandard work. Reality is not like an easy-going boss you can conn into giving you some slack because you meant well; it is more like a great force of water that will implacably exploit any opening you allow it. You may feel like you have done fine, and for many years, but until you start measuring you are only guessing. And you probably reckon that it is inevitable that trail routinely has to be rebuilt, and you probably blame it on "the water". Wrong! Well-built trail lasts longer, but you will never find out until you start measuring it.
There is much to be said about tools and their use. Here are just a few notable tips.
¤ Essential measuring tools. In Measuring Grade the necessary tools were discussed. Here I would like to remind you of three key tools: the leveling scope, the pencil level, and the 25 foot retractable tape measure. Having learned how useful they are I use them constantly. Without these tools on my person I feel like a cowboy without a horse.
¤ 100 foot tape: put a big red mark every 100 inches.
¤ Clinometer? Don't use a clinometer! (At least not for construction.) For sure that would be slightly better than not bothering with grade, or just guessing. But better to use a leveling scope and fully embrace "rise over run"
¤ Cheap plastic slide rule: For those rare occasions when you have to divide some wild numbers, a cheap slide rule can be very handy. Otherwise, pencil and paper is quite suitable for working out the occasional long-division.
¤ Wheelbarrows: Do not use buckets for any substantial hauling of material! (Unless it is small enough you are happy to do it all by yourself.) Especially do not have volunteers do substantial haulage with buckets, as it tends to burn them out. Use wheelbarrows instead, and particularly the smaller four cubic-foot capacity barrows available at your local neighborhood hardware store. Even if it takes two people to carry the barrow up a narrow, irregular mountain trail, the ease of subsequent excavation and haulage will make it worthwhile. Do not use the light-weight "garden" variety of wheelbarrows (typically having a tubular handles), as they are just too flimsy for hauling dirt. If only half or even a third of your volunteers are strong enough and skilled enough to drive a barrow (the other volunteers can shovel and rake) you can still move two to four times as much dirt as with buckets.
¤ Pencil level: Did I mention you should have a pencil level?
¤ The Magic trick: "Rise over run" is inherently a ratio, and potentially can require the use of that most dreadful of arithmetic operations, division. But never fear, just remember the magic trick (because it makes long division disappear) of measuring grade with a base of 100 inches: with a denominator (the bottom part) of 100, the numerator is the grade. Or use a sub-multiple, such as 50 (or 33.3) inches, and simply multiply the measured rise by two (or three) to get the grade.
¤ Something good to keep in mind: 8 feet 4 inches is ... 100 inches!
¤ Easier than falling off of a horse: To measure grade quickly and easily try this: Extend a tape measure 50 inches horizontally from your ankle, resting the end on the tread. Place a pencil level in the trough of the tape, adjust the point of contact against your angle until the tape is level. Grab the pencil level, put your finger at the point of contact, then use the tape to measure the vertical rise. Double that number to get the grade. An excellent way of spot checking the grade. Also impresses people with your expertise.
¤ Out-slope: Out-slope should be only two to six percent, which is only one inch (or less) across a two-foot wide trail. This is too subtle to judge by eye alone; even experienced trail builders usually over do it. Keep in mind Wellington's dictum: "no man ever acquires a very trustworthy faculty of guessing at a horizontal line." My first tip: Measure it! Second tip: if you are using inexperienced help, don't even tell them about out-sloping. Have them grade to a horizontal cross-section, then come back later and do the subtle work yourself.
¤ Staking: Any where the elevation may be tricky – such as switchback turns, steps, walls, bridges, or any other special construction – use surveyor's stakes to control elevation. See Flagging and staking a turn for details and tips, and also Vertical Control and Staking.
¤ Stationing: On any long section of work where the grade may be critical (such as switchbacks!) set stakes (stations) at every 100 (or 300) inches. See Stationing for details. This is guarranteed the easiest way to manage grade.
¤ A nifty datum to know: 300 inches equals 25 feet.
¤ Reducing grade: Usually the elevation gain (rise) is fixed, so the only way to reduce grade is to make the run longer. Some ways of doing this:
¤ Look at the bigger context: Don't just fill a mud hole, look at why it exists. Before working on a section of trail, look at the adjoining segments and see if there is any interaction. Don't put a lot of work into a segment of trail without checking if it might be better rerouted.
¤ Wellington on reconnaissance: I have seen that many (most?) trail builders, when scouting a line for a new trail, will take the first line that seems adequate, rejecting other possibly better lines without looking at them. The great railway engineer Arthur Wellington, noticing the same effect, commented that no possible line should be rejected without being properly examined. You should not be so hurried that you fail to do a thorough and proper investigation, and that means looking at all possible routes.
The shortcutting of switchbacks is a major mode for destroying a trail. Trails – and especially switchbacks – need to be designed in the first place to prevent shortcutting.
First, build good trail. When a trail seems to wander, or go up and down unnecessarily, users wonder if there is a better way. On the otherhand, a trail that proceeds competently and efficiently gains the user's confidence that it is the optimum way to go.
Of course, there are the hotshots (though I would change one vowel) who will cut switchbacks not for a shortcut but for the thrill. For such cases multiple approaches are needed. Keep in mind that you don't have to stop everyone that takes a shortcut – just the first person. The first person may be deterred when there is no indication that anyone else has cut. But once a shortcut is visible others will be more inclined to follow; this becomes a case of closing old trail (discussed below).
A key factor in routing a trail is to minimize the number of switchbacks, and locate them to minimize the shortcut potential. (Ideally the legs should not be intervisible, so that users do not see that there are any potential shortcuts.) Wide radius turns are useful by increasing the separation between the two legs, and all the more so if there is a substantial berm, or intervening obstacles. Careful location might make the most of natural obstacles such as topography (the best), rocks, logs, or heavy brush. If natural obstacles are thin they will need to be augmented by dragging in brush or even logs. (This will be less work than trying to close and revegetate a shortcut.) Fences can also help, but they have to be substantial enough to do the job. The typical woodsy split-rail fence is probably best placed part way down the slope, with a thick patch of brambles encouraged to cover it.
Nothing encourages shortcutters more than a visible, established shortcut. When shortcutting starts effective measures should be taken to immediately nip it in the bud. "Should". It seems typical to pay millions for fighting fires, and totally ignore fire prevention. But it can be a very effective preventative if a trail is routinely patrolled (sufficient for the volume of use), and the patrollers faithfully maintain the logs and brush between any switchbacks.
Once a shortcut trail becomes visible it attracts further usage; shortcuts should be closed as soon as possible. This is much like closing any other trail, except that the temptations of shortcutting usually require stouter barriers, and the steepness of a slope may be a substantial challenge.
Reliance on signs for closing trail is naive, as most people ignore them. Where much effort has been spent to deconstruct a trail and conceal its location, the main effect of a sign will be to show where to find it. If a well-known trail must be closed and deconstructed, then notice of same should be posted at nearby trailheads and the nearest junctions, to inform users that it no longer exists.
Heavy duty fencing (such as cylcone fencing set in concrete) is less effective than might be expected, as users generally just beat a trail around the end. A big patch of Himalayan blackberries, founded on unclimable slopes on either side, is more effective. If you have a wide trail popular enough that users keep trimming back the brambles, try this: a year (or two?) before the planned closure build cyclone fencing well back into the blackberries on either side of the trail, leaving a gap for traffic. After a year or two, when the fencing is thoroughly over-ridden by the brambles it is a simple matter to close off the gap.
Big gaps of missing tread are not sufficient to close trail, but do help communicate to most users that "Yes, this trail is supposed to be closed." More effective if done in a swamp, or with blackberries.
To effectively close a trail it really has to be deconstructed, so that there isn't any trail.
A lot of trail work is the replacement of old trail, which then must be closed to avoid further damage (or even injury to users). I have found the following multi-step process to be very effective. The goals are to: a) prevent erosion, b) reduce attractivness of use, c) breakup visual patterns that suggest a possible route, and d) encourage re-vegetation.
1 - Start by breaking up the old compacted tread by driving in a pick, then giving it just a little lift. The goal is not to till or dig out the soil, but just to loosen it to better retain water, encourage roots, and to provide better adhesion for the fill material by roughening the interface between the fill and underlying base.
2 - Change the shape of the ground surface. Old tread is often like a ditch. At the least fill it flush with the surrounding ground surface. (The fill needs to be at least as substantial as the underlying subsoil.) Add additional irregular mounds to break the linear pattern of the former tread, and to discourage future use. Leaving an occasional pothole is also good, as they make the surface more irregular, and may also retain water for the vegetation. Old traverses should have the outside edge pulled up (but minimizing any damage to established roots) and filled against the inside edge to partially restore the original slope. Any remaining tread should be severely outsloped to better camouflage it and make it less convenient to use.
Tip: it is optimal if soil cut from a new traverse can go directly to filling the old traverse, but how do you accomodate any traffic between closing the old route and opening the new route? Once the new route has been de-brushed but before the start of serious excavation, cut a minimalist primitive trail across it. This can be narrow, crude, and even steep, because it is temporary. As excavation proceeds keep re-cutting this temporary trail so it remains passable. Once you start deconstructing the old trail be sure it is clear to users to take the new (rough) trail; you may want to post signs at each end explaining the situation.
3 - Add water bars (wood or rock) and check dams to prevent erosion. On steep slopes (such as shortcuts between switchbacks) these need to be solid enough that they won't be torn out if some errant hiker climbs over them, or protected by substantial barriers. A few largish boulders well set "in the middle of the road" do more than any sign to focus an errant hiker's attention on the unsuitability of continuing.
4 - If there is any chance of anyone trying to use the old trail: drag in some heavy logs to make substantial barriers. Don't forget that all your other effort here, and even a year of regrowth, won't be noticeable under a few inches of snow. Someone that has used the old route before might not even notice that it has been closed. Even a few logs across the trail might be reckoned as no more than natural windfalls. (I know of one case where the logs were sawed out, possibly in the belief of doing a public service.) An actual fence would better communicate a deliberate closure. If this is only a minor reroute, where one route was expected and one route was found and no great disappointment of expectations, this shouldn't be a problem. But closing a side trail will require barriers that are substantial, and extending well up the trail. Ideally the entire trail should be deconstructed; in practice enough trail should be deconstructed to discourage any expectation that the remainder might be useable.
5 - Add topsoil. Preferably the rich, black, organic stuff that you usually scrape off of the trail.
6 - Optional: add lots of foot-sized or larger rocks. These visually distract from any pattern of the tread, and will interfere with any attempt to traverse. Be careful that the rock itself does not form a pattern showing the old tread.
7 - Transplant some large, bushy plants to fill in any "visual holes". (In the Pacific Northwest sword ferns are typically used; use what ever works in your region.) Transplanting is a minor art in itself, and takes some skill. This is best done at the beginning of the rainy season; otherwise you may need return frequently through the dry season to provide watering lest everything dries up and dies.
8 - Final artistic touch: liberally scatter duff and leaves over the disturbed area, and add twigs and limbs to fill the volume and generally suggest that no one has passed through. A larger limb or two, artistically placed to break up any visual pattern that might suggest the former trail, helps to forestall any idea of a possible shortcut.
An interesting variation on this process has been successful. In a particular case where a switchback was rebuilt we had to deconstruct the old traverse, which was right in view just below the new traverse. Because of the steepness of the slope it was not possible to fully restore the original shape of the slope. So after step 2 we piled on all the brush that had been cut out for the new traverse (and saved), and then tossed soil (copiously supplied from the new traverse) on top. Anyone that has tried this will know that this is not the way to bury brush – the soil tends to fall through, leaving much of the brush sticking out. Which is exactly what was desired. Additionally, to the extent that the brush was buried it formed a matrix that helped hold everything in place. The following spring the scar of the old traverse still showed as a zone curiously devoid of green brush, and a careful examination would have revealed a break in the surface of the slope. But the total obliteration and burial of the former tread removed all attraction as a shortcut. A year later, when the brush had started to re-colonize the fill, it was "plausibly deniable" that there had ever been a trail there.
Finally, here is a wonderful picture of switchbacks at Zion National Park (USA). Strictly speaking these switchbacks are not relevant to this discussion as they are built on rock, not soil. Still, the principles are the same, and they should be an inspiration as to what can be done.
Picture by Lloyd Treichel.
Back to Switchback Theory and Principles.