Assessment of path condition

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Five indices are used to assess a range of ‘qualitative’ aspects of each section along the route. The five factors are roughness, drainage, erosion, dynamism and condition. A scale of 1 - 5 is used to score each section for each of the five indices. Throughout the survey a score of 1 represents the worst condition, most active or higher priority sections, and a score of 5 the least damaged, least active and lowest priority sections.

Condition

This is an assessment of overall current condition including bare width and trample width, drainage and surface condition. When recording this information relate the assessments to reference photographs or the descriptive table (see below) and do not score sections on a relative basis.

Dynamism

Dynamism has been used to describe the rate at which a route is developing (usually deteriorating). Assessment of this process will be based on judgements about rates of erosion and how quickly path width is increasing, or the path is braiding.  This is quite a difficult process to assess as a route may be highly damaged but reasonably stable and therefore not dynamic. Conversely, a route may not be in very poor condition at present but might have just passed a threshold that will lead to rapid breakdown. For example, surface vegetation might have recently been removed through trampling pressure exposing top soil surface underneath.

Drainage

This index measures a combination of water flow (including seepage) and standing water.

It is obviously easier to get a better idea of drainage conditions during or immediately after heavy rainfall, although this is not always practicable and sometimes assumptions will have to be made about drainage. However, there are a number of indicators that provide clues to drainage conditions when a route is surveyed in dry conditions, some of which are fairly obvious.

Examine the surrounding ground. The presence of peat or clay soil usually indicates that it is poorly drained, whereas sandy soils and stoney ground are better drained. Shallow soil depth and bedrock close to the surface encourage very rapid runoff of water after rain. Vegetation types usually coincide with different drainage conditions to a large extent and can be used as indicators of drainage.

Observe the condition of the route, if it is gullied it was probably subject to high water flows. Look for material that has been washed from the routes surface on to surrounding vegetation or elsewhere. Check the composition of the surface material, an absence of fine materials may indicate that they have been washed out by surface water runoff. An accumulation of silt on the surface, on the other hand, can indicate the presence of standing water during wet conditions. A wide route and braid lines could also have resulted from poor drainage. Make a note of blocked or damaged drainage features on constructed paths, since damage to these structures will cause drainage problems.

Roughness

This is an assessment of the condition of the routes surface. Research has demonstrated that roughness has a strong influence on width. If the surface is rougher than the surrounding ground, people are likely to stray off and cause trample-related damage either on the margins or on other more comfortable lines.

Erosion

Erosion is strongly influenced by drainage and gradient. However, levels of use, surface material, topography, altitude and vegetation also affect rates of erosion. Erosion is an ongoing process, and a one-off visit to a site will only provide an estimate of the rate at which erosion is occurring.

Combinations of steep gradient, loose surface material, high levels of use, sparse vegetation, bedrock close to the surface, high rainfall and/or rapid thawing with poor drainage have the potential to lead to erosion. Evidence of high rates of erosion includes gully formation or route surface well below surrounding ground and surface material washed onto surrounding ground or vegetation.

Standard indices for Amber surveys

For each of the five indices used, photographs should be appended to show examples of sections scoring 1 (most damaged/highest priority), 3 (average damage/medium priority) and 5 (lowest priority/least damage).

The most difficult part of using the indices is to make sure that the values you use are comparable with other routes, and surveys done by different people. The following table may help to set ‘standards’, but there is no substitute for photographic records to check between routes.

Score Condition Dynamism Drainage Roughness Erosion
1 - Extreme Constructed features mostly broken, sub base exposed, overgrown Path will show major deterioration within a year Deep standing water or waterlogged surface, drains choked or broken or not present Boulders or sub base exposed on long sections Deep gullies or complete removal of surface, actively changing
2 - Severe Path surface badly worn, broken in places, sub base partially exposed Path will show some deterioration within a year Some standing puddles and waterlogged sections, drains inadequate or poor condition Occasional exposures of sub base across path width Gullies through to sub base, partial surface removal, actively changing
3 - Moderate Signs of wear to path surface and other features, some vegetation encroachment Path will deteriorate in 1 to 3 years Small puddles, boggy sections, drains functioning but close to capacity Pot holes across part of path – not continuous Scouring of surface, no sub base showing, loose material present
4 - Minor Very little sign of problems Path will deteriorate in 4 to 6 years Drains functioning but needing attention Occasional potholes or uneven surface Slight scouring of surface, little sign of active change
5 Negligible Path can be used by all intended users Path is stable All drainage in good working order Smooth surface appropriate to materials used No obvious signs of scouring

 

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