We were commissioned to undertake research on 'Path Attributes'. The purpose of the research was to improve the way that paths are described and we developed a coherent framework for describing any path.

We focussed on the different characteristics of paths which might help people to make a decision about using a path.

Executive Summary

Scottish Natural Heritage commissioned this research to understand how best to provide information which describes the physical characteristics of a path to potential path users. The objective is to enable them to decide if a particular path is likely to be suitable for them.  This is with a view to increasing the confidence of path users and potential path users, helping to increase participation in informal recreational activity outdoors.

This research recognises the importance of separating physical characteristics of a path, which can be measured or described objectively, from the experiential characteristics that would be applied subjectively by different users. This distinction between objective and subjective information helps to eliminate the inconsistency that has been applied to path descriptions and places the path user as decision maker, rather than the path manager.

A ‘standard’ vocabulary has been developed to give a consistent meaning to various terms, and where possible particular adjectives are anchored to measurable values or ranges of values. Each characteristic, and its associated descriptors, is considered and these have been grouped into four main categories of physical characteristics:

• Gradient (along and across the path)
• Path surface (materials and condition)
• Obstacles
• Clear width and height

The outputs of the research also provide a new framework for describing paths in a coherent manner, enabling path managers to produce consistent descriptions in different locations and settings. This framework has been defined as the Restrictive Properties Continuum (RPC) and can be applied to any path to produce a description of its physical characteristics.

The RPC can be used to provide ‘shorthand’ information about paths within the bounds of classified physical properties, for example a range of grades from A to E or 1 to 5 based exclusively on measurable characteristics. This has the potential to facilitate route choice and help potential users to easily recognise paths that are within their physical competence. These grades can be consistently applied throughout Scotland raising confidence amongst path users that the information will meet their expectations and match their own experiences of paths.

This study involved desk-based and qualitative primary research to evaluate which path characteristics are important to different users of paths and builds on current practice in Scotland and abroad. A wide range of path users and non-path users participated in the research providing their own opinions as well as feedback on proposals put forward from the desk-based research. The participants included walkers, cyclists and horse riders of different degrees of confidence and competence. In addition, some feedback was gathered from people with disabilities and ethnic minority groups.

Further investigation is recommended to quantitatively assess the outputs of this research and to evaluate the potential for implementing the RPC across Scotland.

Standard Vocabulary for Paths

This ‘standard’ vocabulary has been developed to give a consistent meaning to various terms, and where possible particular adjectives have been anchored to measurable values or ranges of values. The vocabulary has been grouped into four main categories of physical characteristics:

• Gradient
• Path surface (materials and condition)
• Obstacles
• Clear width and height

Gradient

There are two types of gradient on a path:

• the long gradient (in the direction of travel) - this helps people to gain an idea of the exertion required to use the path.

• the cross gradient (across the path or direction of travel) - this helps to describe the potential difficulty for people who use wheels (wheelchair users, pushchairs, cycles with stabilisers etc) or have mobility restrictions and may be helpful to horse riders in some situations. This is most often referred to as cross-slope.

Where specific measurements are provided, the use of a percentage is preferred (in common with road signage).

Adjectives for gradient along the length of a path

Absolute values described above require 3-dimensional awareness and a degree of mathematical literacy. It is therefore proposed to use 'relative values' that are based on ranges of absolute values:

• flat - Path must actually be flat with no inclines greater than 2% (1:50)

• gentle - Slopes between 2% (1:50) and 5% (1:20)

• moderate- Slopes between 5% (1:20) and 10% (1:10)

• steep - Slopes between 10% (1:10) and 20% (1:5)

• very steep - Slopes greater than 20% (1:5)

Adjectives for cross slope

There is greater sensitivity to changes in cross-slopes particularly amongst people with restricted mobility, meaning that the terms used above would be unlikely to provide helpful descriptions of the terrain. For example, on roadside pavements a 2% (1:50) cross-slope is considered a barrier to some wheelchair users.

The following categories of cross slope are proposed:

• minor - cross slope of the path surface is less than 2% (1:50)

• significant - cross slope of the path surface is between 2% (1:50) and 10% (1:10)

• major - cross slope of the path surface is between 10% (1:10) and 20% (1:10)

• extreme - cross slope of the path surface is greater than 20% (1:5)

Describing the length of gradient

For some users the horizontal length of the gradient is important - it will help to determine the exertion required to use the path. In reality the length of gradient on the ground surface represents the hypotenuse of a triangle with a horizontal length and a vertical height gain, but it is not considered helpful to differentiate this aspect and the distance on the ground (e.g, measured with a wheel or tape) should be used instead of a calculation from a map.

However, it is considered to be useful to describe, in relative terms, how long the gradients are on a path. The following situations are considered to be an appropriate combination of adjectives and actual values:

• Short: a gradient of less than 10m duration

• Prolonged: a gradient of more than 100m but less than 200m duration

• In situations where the gradient is more than 200m long a slope could be described as prolonged for [add distance] or simply with the distance stated.

Because there is no common usage of a term ‘medium length’ (i.e. it is unlikely to be rapidly assimilated into everyday situations) it is contended that there is no obvious benefit to describing a length of gradient between 10 and 100m as medium. Therefore all other gradients, where an adjective is not used, should be assumed to be between 10 and 100m in length, although this explanation may need to be available in the early stages of introducing these standard terms.

Combining the steepness and length of gradient in a description

If the vocabulary outlined above is applied consistently and accurately, then it would be possible to describe gradients using a combination of ‘steepness’ and ‘duration’:

• A short steep slope = slope between 10% and 20% for less than 10m
• A prolonged gentle slope = slope no greater than 5% for over 100m
• A very steep slope for 350m = slope greater than 20% for a distance of 350m

Issues with ‘real world’ gradients

It is important to acknowledge that gradients are rarely constant and therefore some approximation will be necessary. In undertaking a path survey it will be necessary to make a judgement call on the appropriate start and end of a particular slope (not the path section), and the ‘average slope’ may be slightly less than the absolute steepest point. It is not practical to provide ‘continuous’ measurement of slopes for use by a wide audience as it would lead to information overload.

Height gain and elevation

Associated with gradients, is information about the cumulative gain (or loss) of height and the elevation data of the path. This information could be used to provide greater richness to a description and where a ‘path profile’ is available, could help to reassure people about the physical exertion that might be necessary. However, there is a tendency to expand the height axis of the profile to provide detail on the relative changes in elevation, but this significantly distorts the apparent gradient. Therefore this information could have a negative effect on potential path users who have limited experience with height profile diagrams.

Cumulative height gain is a measure of the total height climbed along the route ignoring the downhill sections. It could be helpful to some path users to gain an understanding of the likely exertion required and if used by people with experience of Naismith’s Rule of navigation, could help to calculate the likely time required to complete a path. The use of cumulative height gain would also require careful consideration to explore the implications of providing this information without causing confusion with length of gradients.

It is considered therefore that elevation data and cumulative height gain would be interesting, but not essential, information and these characteristics have the potential to cause confusion for some people.

Path surface

Descriptive language

Surface conditions appear to be important to the public - the Health Walks leaders reported that people ask about the path surface for chosen routes when considering whether to participate. There are some technical terms that could be used to describe the material, such as 'aggregate surface', but it may be better to use non-technical terminology even though this might not be as accurate - gravel is not the same as aggregate, but is probably more widely understood. The following broad categories are considered to cover most situations:

Vegetation - this could be 'naturally' occurring vegetation (e.g. ground flora in a woodland, heather or rough grasses), or could include surfaces that have been constructed to give a harder wearing grassy surface.

Soil - this term should cover any unconstructed path surface where the vegetation has been removed (either through trampling or some management action). If it is helpful, a broad indication of the soil type could be used - this is particularly useful where the underlying soil is sandy (i.e. free-draining), muddy (i.e. likely to hold water) or peaty (i.e. likely to deteriorate quickly in wet weather)

Gravel - this should cover most aggregates even if the particle size is technically out of the range of gravel.

Cobbles or boulders - this could include rock steps or pitching

Hard - this could be used to describe any bound surface, eg bitmac/tarmac, epoxy or concrete

Boardwalk – This would include wooden, plastic or metal gangways or raised ‘platforms’. Where a non-slip coating or surface texture has been applied, this information could be provided.

Surface condition

In addition to the construction material, a description should provide additional information regarding the surface condition. This will help people to differentiate between gravel paths of varying construction standard and material – horse riders will tend to avoid compacted surfaces with protruding stones, whereas people on wheels (cyclists, push-chair / buggies or wheelchair users) require increased effort on unconsolidated aggregates. The following adjectives are considered to cover the range of surface conditions:

Smooth - this should coincide with compacted aggregate or bound surfaces with no protrusions or loose stones greater than 10mm.

Loose - probably associated with gravel surfaces where the material used has not been compacted or has no fine material to help bind particles

Uneven - minor variability in the level of the surface (not associated with the gradient or cross slope) that is less than the equivalent of constructed steps (e.g. less than 50mm of height difference within a 1m² area). This could include constructed paths that require repair or maintenance.

Rough - surfaces that are variable (50 - 100mm height difference in 1m² area) and may have loose stones. This may include constructed hill paths that have water bars or cross drains.

Very Rough - surfaces that are highly variable (greater than 100mm height difference in 1m² area). This is likely to be unconstructed paths.

Potholed - may be best to restrict use of this to vehicle tracks that are in a poor state of repair.

Drainage

In addition to the overall 'texture' of the surface, information about the drainage will be of particular interest to users who may base their decisions (wholly or partly) on whether they are likely to get wet or muddy. However, this information should only be included where it adds to the picture (i.e. well drained or poorly drained).

Application of surface related terms

It may be possible to use a descriptive term for the surface type or the surface condition individually or as a composite (e.g. hard surface, uneven surface, or loose gravel). In addition the state of the drainage could be included if it is relevant to the likely user experience (e.g. poorly drained rough peat, or well drained smooth gravel).

Obstacles

This path vocabulary concentrates on obstacles as physical barriers, but recognises that some psychological barriers are likely to have wide relevance (for example, although the exposure to steep drops is more of an issue in terms of fear than something that prevents physical access, this may affect many people's choice of whether to use a path). Obstacles will affect different user groups and individuals to varying degrees, and the listing of some barriers may appear irrelevant to a particular user.

It is necessary therefore to consider potential barriers to all types of user and provide the information in an objective manner. Each obstacle will need to be clearly described to allow people to decide whether it affects them. Where an obstacle appears in different ‘forms’ along the path, such as gates with varied construction, the MOST RESTRICTIVE obstacle must be included, and if space within the description is available, this can be tempered

Types of obstacle

The following list covers the majority of physical barriers but may not be exhaustive, particularly for users with very specific requirements or paths with particular construction features. It is possible that a judgement needs to be made when considering the inclusion of obstacles in a description: a path that as few physical constraints is more likely to be used by people with limited mobility and therefore information about the size and nature of obstacles becomes important for those users. A different path in more remote terrain may not require similar obstacles to be described as fully if there are more significant obstacles to be included in a brief description.

Steps - it is necessary to describe whether steps are small (less than 100mm rise) or large (greater than 100mm rise), regular or irregular. It may be useful to describe the extent of a flight of steps and whether it has a hand rail (the default position is assumed to be no handrail)

Gates - there is a great deal of variability in the types of gate (i.e. construction material and size), their function (e.g. kissing gate), and their ease of opening (e.g. trombone handles vs chains). Although it may not be practical to describe each gate, the most restrictive gate should be included in the description (e.g. a constricted kissing gate with a bolted latch).

Stiles - stiles can present difficulties or block some users. It may be helpful to include information as to whether the stile has 'stairs' or a simple crossed step, or if a stile crosses a deer fence.

Bridges - in many cases a bridge would be a barrier if it is too narrow to allow horses or wheelchairs, but the approach ramp may be a barrier in itself. In some cases there may be weight restrictions but these are unlikely to affect most recreational users.

Constrictions - these could be width restrictions, such as through a gateway, or height restrictions such as a low bridge, or overhanging branches. This term should be used to describe particular features, rather than as a substitute for declaring the overall ‘dimensions of the path.

Road crossings - these can be a barrier for some user groups, and sections that are shared with traffic may influence some users (particularly family groups with young children on cycles).

Blockages - these could be temporary or permanent features designed to restrict access by motorised vehicles. If it is possible to avoid or remove /open a blockage, then this should be included in a description.

Cattle Grids – these may form barriers where there is no side gate, or the side gate is particularly narrow. Horse riders, wheelchair users and dog walkers are most likely to benefit from this information.

Drop Kerbs – in many urban situations drop kerbs are being removed at main road crossings and textured paving is added for people with visual impairments. It is therefore reasonable to highlight where drop kerbs exist, which is useful for wheelchair users and those with visual impairments.

Exposed drainage features – upland style paths often have cross drains and water bars to manage surface water. These features may act as a barrier to some users and cause inconvenience to others.

River Crossings – where bridges are not provided users will need to be aware of river crossings and whether there are any stepping stones. An important consideration is the nature of the watercourse and likelihood of the crossing becoming impassable (this is particularly important in areas where the catchment is prone to flash flooding).

Exposure to height - giving prior warning can be helpful to some groups of users (e.g. families with young children). Unfortunately this is, to a degree, a subjective consideration and may be difficult for a path manager to judge. It is suggested that any vertical drop at the path edge greater than 10m should be highlighted to allow users to make their own choice.

Clear width and height

The clear width and height refers to the unobstructed area around the path. These are relevant to different users and are therefore considered separately below:

Clear width

The width of the managed surface may help some people to determine whether a path is appropriate for them to use. A number of 'conventions' and standards exist, so it may be useful to use these as the basis of the descriptions. For example, some upland path repairs are specified with 800mm minimum width, many 'all abilities' paths have been constructed with a minimum width of 1200mm and vehicle tracks are commonly 2500mm or more wide. However, informal paths or desire lines may have a much narrower 'walking surface' of 200-300mm.

It is important to recognise the difference between the constructed width of the path and the ‘managed width’ – in some areas a path that was originally constructed as 1200mm has had encroachment of vegetation onto the surface leaving only 200-300mm of desire line and it would be misleading to describe this type of path as having a width of 1200mm.

The following definitions may help to avoid the use of path dimensions in a description:

Narrow: the managed width is less than 800mm wide (i.e. not wide enough for two people to walk comfortably side-by-side or pass easily).

Broad or wide: the managed width is greater than 1500mm

Where construction standards and guidelines exist, the width of constructed trails is generally recommended to be between 800mm and 1500mm, and this has effectively become an ‘expected width’ for existing path users (i.e. what a path user might visualise when thinking of a path designed for non-motorised access). In addition, it is not considered that a managed width between 800mm and 1,500mm represents an obstacle for path users in itself. Therefore, in cases where the managed width is between 800mm and 1500mm it is not considered necessary to add to the description. However, providing information about constrictions will be particularly helpful - this information could be included as an obstacle. As in the case of gradient, this assumption would benefit from being explained as part of the introduction of these standard terms.

Clear height

Height restrictions are most likely to affect horse riders, but may be of relevance to people who are claustrophobic. However, care is required to ensure that the description is not misleading - for example occasional overhanging branches across part of a path may not cause any impediment.

The minimum clearance for horse riders to use a path safely is 3m (10ft), although some larger horses may require additional height. Therefore specifying the measurement is more useful than a general statement about low bridges. Where a single height restriction occurs it could be included in the description as an obstacle.

Data collection for developing path descriptions

A standard data model has been developed to assist path managers in collecting appropriate data to facilitate writing path descriptions. Where a path is divided into discrete sections or ‘path links’ it is important to collect separate data for each link. This provides greater flexibility in presenting the path description and potentially results in ‘information rich’ sources that can be important for people with specific requirements. Data storage and retrieval needs to be carefully considered, but creative use of technology may allow information rich descriptions to be accessed without added burden on the path manager.