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April 16, 2015 in Listings

Hiking Classifications


Class 1
Class 2
Class 3
Class 4
Class 5
Class 6
Class 7
Class 8
Class 9
Class 10


After receiving several inquiries about the difficulty of hikes, I began a long search for a system that would help to describe the difficulty that one would encounter on any given trail. I ended up stumbling upon quite a few systems but they all tended to be overly simplistic or were very specific to a certain terrain, like the Australian Standard that was designed for the Australian outback, or the SAC (Swiss Alpine Club) scale that was designed for Swiss alpine conditions.

I instead decided to try and formulate a system of my own, one that would be almost completely based on data that had been accumulated by my Suunto watches, in an attempt to ensure that the ratings were derived from the plethora of quantifiable factors rather than personal or subjective experience. I began by trying to determine what categories contributed to the difficulty of a hike and how they could be quantified, and ultimately ended up with five : distance, duration, ascent, elevation, and terrain. Each of these categories were then assigned ratings from 1-10 to measure how challenging they were. The ratings from each of these five categories were then averaged out to give a final rating that then corresponded to one of the ten classes in order to indicate the overall difficulty.

Example : Stirling Ridge.

Average daily distance : 9 km (rating 4)

Total duration : 3 days (rating 7)

Average daily ascent : 1200 m (rating 7)

Terrain : Scrambling (rating 7)

Average elevation : 740 m (rating 1)

Average rating : 5.2 (Class 7 - Challenging)

I have to admit however, that no system is perfect and that the difficulty of a hike is also very dependent on unquantifiable factors such as the conditions of the trail and the prevailing weather, as well as the physical abilities of the hiker. Just be sure to take each of these ratings with pinch of salt and be very aware of your own personal limitations when reading the trip accounts.

The Classes

There are ten different classes that range from 'Extremely straightforward' to 'Abominable'. These classes encompass a range of difficulties that is almost twice as wide as almost every other system out there. The classes are determined by averaging out individual ratings derived from five different categories, namely distance, duration, ascent, elevation, and terrain. Clicking on each of the classes will bring you to a list of hikes that fall under that class.

Category Class 1 Class 2 Class 3 Class 4 Class 5
Difficulty Extremely straightforward Very straightforward Straightforward Fairly straightforward Moderate
Rating <2.0 2.0 - 2.5 2.6 - 3.1 3.2 - 3.7 3.8 - 4.3
Category Class 6 Class 7 Class 8 Class 9 Class 10
Difficulty Fairly challenging Challenging Very challenging Extremely challenging Abominable*
Rating 4.4 - 4.9 5.0 - 5.5 5.6 - 6.1 6.2 - 6.7 >6.7

* A very apt term that has been borrowed from the 'ABO' grade of the French Alpine System

The Ratings

Rating 1 2 3 4 5
Distance <2.5 km 2.5-5 km 5-7.5 km 7.5-10 km 10-12.5 km
Duration <2 hours 2-4 hours 4-6 hours 6-8 hours 1 day
Ascent <200 m 200-400 m 400-600 m 600-800 m 800-1000 m
Elevation <1400 m 1400-1900 m 1900-2500 m 2500-3100 m 3100-3700 m
(>85% O2 sat) (80-85% O2 sat) (75-80% O2 sat) (70-75% O2 sat) (65-70% O2 sat)
Terrain Paved or Wooden Walkways Gradient <5% Gradient 5-15% Gradient 15-25% Gradient 25-35%
Rating 6 7 8 9 10
Distance 12.5-15 km 15-17.5 km 17.5-20 km 20-25 km >25 km
Duration 2 days 3 days 4-6 days 7-10 days >10 days
Ascent 1000-1200 m 1200-1400 m 1400-1600 m 1600-1800 m >1800 m
Elevation 3700-4400 m 4400-5000 m 5000-5800 m 5800-6600 m >6600 m
(60-65% O2 sat) (55-60% O2 sat) (50-55% O2 sat) (45-50% O2 sat) (<45% O2 sat)
Terrain Gradient >35% Scrambling Climbing Roped Technical

The Categories

Distance

Distance is one of the major categories that contributes heavily to determining the degree of difficulty of any given hike - the longer one hikes, the harder the hike gets. Occasionally one comes across a hike that has a daily mileage that is so large that the corresponding category rating overwhelms most of the other factors. One example of this is the Cape 2 Cape hike, a week-long hike that requires walking up to 30 kilometres a day over multiple days, but has almost no elevation gain and is on fairly easy terrain, yet has an assigned difficulty rating of "Fairly Challenging".

Example : Cape 2 Cape (class 6)

Total distance : 136.9 km

Average distance over 6 days : 22.8 km (rating 9)

Duration

Duration is another category that is closely linked to distance. This category however, is highly dependent on a whole range of other subjective factors, the biggest being the walking speed of the hiker. If you are concerned about your own speed, it might be advisable to plan accordingly and to take a more conservative estimate by adding on to the time (as seems to have been done here). Bear in mind that for multi-day hikes, acclimatisation/rest days and days that have been allocated for contingencies are not taken into account.

Example : Mount Stong, Mount Ayam, Mount Baha (class 5)

Total duration : 6 hours (rating 4)

This was actually in between ratings, but since we
were a very small group that was travelling fairly
fast, I decided to choose the 'higher' rating.

Ascent

Ascent is not the elevation of the summit, but rather the accumulated elevation gain. Certain hikes have multiple undulating ascents and descents prior to reaching the final summit and this category takes that into account. The Pine Tree Trail for example, begins at an elevation that exceeds 1300m and has a peak elevation of 1448m, yet the elevation change exceeds 900m, a number that is far higher than the net elevation.

Example : Pine Tree Trail (class 4)

Ascent : 910 metres (rating 5)

Elevation

Elevation is the average elevation of the entire hike. Elevation is a very important factor to consider since the amount of oxygen in the air (shown as % of o2 saturation at sea level) decreases exponentially with an increase in elevation. This is because the increase in elevation also brings about an exponential decrease in the atmospheric pressure. Oxygen has approximately half of its sea-level value at 5000 metres, the altitude of the Everest Base Camp; and only a third at 8848 metres, the summit of Mount Everest. Aside from possible medical problems such as acute mountain sickness (AMS) and the potentially fatal high-altitude pulmonary edema (HAPE) and high-altitude cerebral edema (HACE), the body also responds to this decrease of oxygen with altitude acclimatization.

For multiday hikes that have an average elevation that can affect the difficulty rating, a system that averages that total 'averaged' daily elevation is used (since GPX files are separated by days). The system takes into account the time spent at that average elevation in hours and minutes for each day, and gives it a specific 'weightage' in order to increases the accuracy of the total average.

Example : Everest Base Camp & High-Altitude Passes (class 8)

Average elevation : 4325 metres (rating 6)

The figure above was derived after the 'weightage' system was applied. Day 13 (Chola Pass) for example, was an 8-hour hike at an average elevation of 5127m; whereas the hike to EBC took 3-hours (return) at an average elevation of 5241m. The former carries 2.7 times more 'weight' than the latter.

Terrain

Terrain is a rough categorisation of the range of terrain that one might encounter. The ratings start with easy and broad, modified surfaces such as paved, cemented or wooden walkways; and then goes on to dirt trails that steadily increase in gradient from the second rating to the sixth. The ratings then progress up to scrambling up and down rocks or scree (such as Tabur), and actual unroped vertical rock climbing, such as sections of the Western Arthurs; and ultimately culminates with roped climbing and technical climbing on the extreme end.

The ascent gradient is calculated by first determining the amount of the total distance that was covered during the ascent phase (discounting flats and descents). The ascent is then divided by the 'ascent distance' and then multiplied by 100 to give the gradient in percentage (calculations shown below). A gradient of 100% is therefore equivalent to an incline of 45° since the rise and the run are exactly the same. In order to determine the angle of the gradient (in degrees) however, one needs to employ simple trigonometry—the inverse-tangent of the rise divided by the run. So for the example below, arctan 5191/46500 will give you an angle of 6.4°. Both the percentage as well as the angle for each rating have been included for convenience.

Example : Western Arthurs (class 7)

Total distance : 93360 km

Ascent distance : 46500 km

Total ascent : 5191 metres

Ascent gradient = (5191/46500)*100 = 11.2%, 6.4° (rating 3)

(The Western Arthurs has sections that are completely vertical however, which upgrades the terrain rating to an 8)

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