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TRAIL DESIGN AS AN INDIRECT TOOL FOR WILDERNESS USERS MANAGEMENT:
POTENTIAL OF GIS MODELLING
MARTIN LEDANT
DEPARTMENT OF GEOGRAPHY
UNIVERSITÉ DE LIÈGE, BELGIUM
I N T R O D U C T I O N
The definition of wilderness, although it may
vary widely according to sociological and cultural
factors, is often balanced between two ideas.
They are expressed in the American Wilderness
Act of 1964. Wilderness is firstly an area “which
generally appears to have been affected
primarily by the force of nature, with the imprint
of man’s work substantially unnoticeable”.
Secondly, it must have “outstanding
opportunities for solitude or a primitive and
unconfined type of recreation”. This definition
thus states that wilderness is an area dedicated
to Nature’s own will but also recognize that its
experiential opportunities should be made
available to human recreation.
This ambiguity between dedicating
wilderness to both Nature and humans is at the
basis of one of wilderness paradoxes. Indeed,
wilderness areas can easily cope with the
passage of a few visitors, but the increased
abundance of visitors in those areas is
destroying the very thing that is tried to be
protected (Knight and Cole, 1991). Excessive
recreational use affects both the ecological and
experiential sides of the wilderness and may be
the main threat to wilderness today (Hendee et
al., 1990).
Ecological impacts of recreation include
anthropogenic erosion, disturbance of biota via
trampling, water pollution and wildlife
disturbances. Experiential impacts include a
reduction of opportunities for solitude, a
reduction of feeling of naturalness (i.e.
devegetated campsites, improper shortcut), and
annoyance by other visitors behaviours (Hendee
et al., 1990).
Some of these impacts can be eliminated or
reduced by management of wilderness users.
However, management can enter in conflict as
well with the wilderness experience by interfering
with users’ freedom. Thus, it is fundamental that
only the minimum management is applied to
achieve the objectives required. In this
perspective, management which act on the
factors which influence people’s choices rather
than directly on people’s choice appear to be the
most appropriate as they do not interfere with
users freedom and their wilderness experience.
For instance, educating people can prevent the
majority of the “unskilled actions” or careless
behaviour such as littering or plant harvesting.
On the other hand, recreation always has a
minimal impact which is unavoidable, for
instance every user generates a “presence”
which might diminish other’s feeling of solitude.
Another example is trampling of soil and
vegetation which difficultly avoidable. However,
some management measures exist to reduce
those unavoidable impacts.
A big and growing part of recreational
activities in the wilderness are associated with
trails (Cordell et al., 1995 in Linn and Brown
2003). As discussed further, trails have a strong
influence on people behaviour, and reversely
much of the recreational impacts are dictated by
the presence of trails. In the light of the above
discussion the understanding of the processes of
trail formation, their potential or desired locations
may prove itself to be a useful tool for indirect
management. Actively designing the layout of
trails can enhance the wilderness experience
and reduce the biological impact of users with
minimal visible management interference. It is
this idea that this present essay is dealing with.
In support to the discussion an insight into the
potentiality of GIS based model in mapping
users’ behaviour and “desire lines” for effective
management. This model is applied to the

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particular location of the Ennerdale Valley in the
western Lake District (Great Britain). Particular
considerations to this particular location are
being stressed.
C O N S I D E R A T I O N S R E G A R D I N G T R A I L S
Trails result of the repetitive human
trampling of the soil cover. Trampling has at least
three effects on the natural environment: loss of
vegetation cover, soil compaction and soil
erosion (Cole, 2004). The vegetation around a
trail can be seriously affected by trampling.
Liddle (1997) reports a reduction in number,
vigour and heights of plants subjected to
trampling. Soil compaction can increase water
infiltration and increase runoff and erosion
potential. Trails can become deeply eroded when
the disposition of the trails allows water to be
channelled down the tread (Hendee et al. 1990).
Finally, when intensity of usage is high, the
erosion induced can be very severe. Lance et al.
(1989) describes how the increase in use after
an access road and chairlift were built in the
1960s in the Cairngorms had a dramatic impact
on the width of the majority of the trails. In
addition, trails can affect the wilderness
experience if they proliferate in anarchic patterns
which scar the landscape. Multiple, parallel or
braided trails or shortcuts form when people are
unhappy with the trails they are following.
Trails can therefore be seen as a negative
impact resulting from recreational use. However,
trails are also a great opportunity to manage
wilderness users’ impact.
First, a major quality of trails is that people
tend to follow them. Helbing et al. (1997)
demonstrated that pedestrian movements are
accessible to mathematical description because
they rely of self-organisation. Human psychology
wants that someone would rather choose to walk
on a trail rather than across the land. This is
because they are easy to find, easy to travel,
and easy to use (Hesselbarth et al, 2007). The
practical implication of this statement is that if
users are provided with an efficient trail network
use patterns can be influenced.
Secondly, it appears that the spatial
distribution of hiking impact at a large scale is
mostly “concentrated along trail corridors, with
little impact off trails” (Cole, 2004). Furthermore,
it has been shown that the relationship between
frequency of use and intensity of impact is
curvilinear (Fig. 1). This means that in places
with low amount of visitors small increases in
frequency create more damage than if the trail
was already frequently used. This implies that
encouraging the use of a restricted number of
trails and discouraging users to venture outside
the trails has the potential to limit the overall
impact. This can be done mainly by information
and education (Cole, 2004) or by providing trail
layout meeting users’ satisfaction requirements.
To summarize: people are attracted to trails
and their impact can potentially be concentrated
around those trails. This has good implications
for the ecological side of wilderness. However,
this has also negative implications on the
wilderness experience. Indeed, people might not
want to be constrained on a set of paths, and
even less when those concentrate other users
and human impacts. This problem can be solved
by having recourse to an intelligent and
sustainable design of the trails layout.
Trail design has the potential to (1) solve
problems attached to the trail itself related earlier
and (2) consider the wilderness experience of
the trail user.
First, it is recognized that trail conditions are
influenced by their environmental characteristics
(Leung and Marion, 1996). Among them, terrain
and topography play a major role. A large
amount of literature exists in the United States
relating of the effect of trail slope and other
geometrical parameters on trail deterioration
which should be considered while building a trail.
Secondly, studies suggest that resistance
and resilience of vegetation covers may vary. For
example Cole (1995b) shows that groundcover
plants of forested site, usually composed of more
erectile and broad-leaved types, are more
quickly lost due to trampling than ones in open

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woodlands or meadows. Similarly, soils
sensitivity to trampling may vary. Studies have
shown that erosion is most severe is soils of
homogeneous textures (sand, silt or clay rather
than a combination) and that lack rocks (Bryan,
1977; Root and Knapik, 1972 in Hendee et al.
1990). Considering this, locating trails in less
sensitive areas may reduce drastically the trail
conditions and prevent the formation of new trails.
In areas where this option is not feasible, trail
conditions can be preserved by engineering-
surfacing, bridging or ditching but those often
result in undesirable effect on wilderness
experience and should be kept to a minimum.
Secondly, although designing the physical
setting might go against experiential values, it
seems that on the contrary this technique has
the potential of encompassing wilderness
experience criterion. Hendee et al. (1990) see
trail design as “a unique opportunity for manager
to subtly program visitor’s experiences almost as
though they could write a script that visitor had to
act out”. Indeed, both the sequence of visual
experience and the level of challenge can be
manipulated in order to enhance the wilderness
experience. By intelligently designing the trails,
anthropogenic features or trail traffic
observations can be reduced and scenic or
ecologic beauty can be improved. On the other
hand, the trail can be made deliberately
challenging with a relatively high degree of risk
or on the contrary easier in consideration of
people with different abilities. However, the
design must also consider that the trail takes the
path of least resistance; otherwise, users will
create their own trail (Hesselbarth et al, 2007).
Trail design may sound attractive on paper; it
is often not an option. The first reason is that
most wilderness trails today are trails that were
historically built in other purposes than recreation
(i.e. fire control, or people transportation) and
consequently doesn’t meet the train design
concepts. The second reason is that trail
construction, relocation and maintenance is
expensive and the available funds are often
scarce.
However, if proactive trail designing isn’t
always an option, understanding the actual
network in a particular wild area, the reasons
resulting in the apparition of a trail, the character
of a trail and the experience it provides may help
the manager taking decision concerning possible
rerouting or areas which require attention.
T R A I L M O D E L L I N G
Following this approach, a GIS model was
created. The model is based on algorithms more
commonly used in modelling of hydrological
processes. Digital terrain models are used to
determine the direction in which water flows,
subsequently the amount of water passing by
every location of the study area, and finally map
potential streams. The approach of the present
model is very similar except it doesn’t deal with
accumulation of water but with accumulation of
wilderness users.
To determine the “users accumulation”, we
need to determine in what direction a user would
go at every location of the area assuming that
this direction follows the least cost path between
that point and an access point of the area (i.e.
Car parks or trails access in the valley). The cost
of movement is determined mainly by the slope
and secondly by the roughness of the land cover
(see table 1). The directional information has the
form of the BACKLINK output computed via the
function PATHDISTANCE in ArcGIS (see an
example in map 1).
The “backlink” information can then be used
to compute the “users accumulation” using
FLOWACCUMULATION function in ArcGIS.
Each pixel of the area accounts for one unit
(user) which makes it way to the entry point
Table 1. Cost of Movement Parameters
Land cover friction
Land cover Time cost (s.m-1
)
Broadleaved and mixed woodland 0.72
Coniferous wodland 0.72
Dense scrub Barrier
Heathland 0.72
Improved Grassland 0.9
Open Water Barrier
Unimproved grassland 0.9
Valley wetland Barrier
Human features
Reclassififed as
nearest
affectation
Rocks and Crags +0.18
Vertical Factor Correction
Follows Naismith's Rule

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following the least cost path. The algorithm
computes for every pixel the amount of unit or
“users” which have flowed through. When this
value is normalized by the total area considered,
the percentage of the area accessible from each
pixel is obtained. It appears that certain lines
drain the majority of the area and therefore can
be expected to concentrate the users. This
concentration increases as the trail gets nearer
to the source (see map 2).
However, trails are most of the time not
related to one and unique source. When there
are multiple entry points, each entry may
generate its own set of trails. To take this factor
into account, the above procedure was repeated
for 9 entry points in total (2 car parks, 7 trail
entrances in the valley). A weighted average was
calculated from the 9 layers (Arbitrarily: weight of
a parking = 4 weight of a valley entrance). The
value of a pixel doesn’t longer represent the total
area drained through the pixel. Instead it is an
indicator of the extent of the area accessible
from that point considering that the user may be
coming from different entry points (Map 3). From
this information, the likeliness of an actual path
to occur can be estimated.
D I S C U S S I O N
The modelled trails and the existing trails
(rights of way) show some co-occurrence. For
instance, for the trails around the lake, along the
crests or at the bottom of the valley there is a
general co-occurrence. Another interesting point
is that the model recognized a path of least
resistance downhill of the Pillar (see map 3 point
1) where an actual trail exists through the rocks
and crags. This shows that the assumption that
users follow path of least resistance is confirmed
to some extend. For instance, around the lake
the trail is flanked between the slope and the
lake, and in the valley following the river is the
easiest option.
However, at the smaller scale, the model
doesn’t always indicate the same path as in
reality. This is the case for the trail coming down
of the Pillar, but it’s also true in some instances
such as around the rock at “the corner of the
lake” (point 1, 2). The trail recognized by the
model may be the least costly overall; the
behaviour of hikers on the terrain might not be
dictated by long distance evaluation of difficulty
but by decision taken on the basis of shorter
distance evaluation. That’s why users may prefer
to choose to follow the lake, even though it will
be longer overall. The increase in length or
difficulty may also be deliberate for the sake of
scenic beauty or work out.
Users may prefer existing paths to shorter
and easier path for psychological reason cited
earlier. It’s the case of the two first trails climbing
up the south side of the valley (4). Land
ownership might also play a certain role in
determining trails patterns and once those are
removed managers may want to pay attention to
formation of new trails. This is particularly true in
places where terrain doesn’t impose much
constrains and where the model consequently
indicates a high density of trail crossing in
different directions (5).
On the other hand, some paths indicated by
the model don’t exist at in reality. This may be
explained by the fact that the model consider a
homogenous usage of the valley (one pixel =
one unit) as where in reality some part of the
valley might be more used than others. There
are two instances at least supporting this idea.
First the trail which runs behind the hill at the end
of the lake (6) and secondly the trails on the
South-East side of the valley (7). None of those
two exist in reality, probably for the fact that
usage is concentrated on the south-west side of
the valley, with all its smaller valley and peaks.
However, the apparition of a trail in those areas
might become likely if pressure on wilderness
experience increase and people start to look for
calmer places.
C O N C L U S I O N
Some aspect of the model may of course be
subject to discussion; in particular the relevance
or sensitivity of certain parameters such as the
location of sources and their weight in the final
result. However for the time being, it is safe to
admit that such modelling of wilderness user’s
behaviour and trail formation can be a potential
tool for assessing the location of impacts of
recreational use of wilderness in a given area.
Furthermore, the model could be improve by
introducing experiential notions such as scenic
and ecological beauty on one hand, and
ecological sensitivity on another in order to

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design a trail layout which maximize wilderness
experience and minimize its impact. However,
such measures, as said earlier, are difficult to
implement in practice. This is especially true in
regions of the world where wilderness isn’t only
under the pressure of recreational use but also
under the one of other kinds of use such as
forestry, or farming. This fact adds on the lack of
fund the necessity to deal with trails which
dates from other time in history when wilderness
preservation and experience were not issues.
Word Count: 2681
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Ecological Applications, Vol. 6, No. 1, (Feb., 1996), pp. 168-184
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