Proposal:Path defined by

path_defined_by
Proposal status:	Abandoned (inactive)
Proposed by:	Rostranimin
Tagging:	`path_defined_by=full_construction:partial_construction:worn_line:indistinct_worn_line:animal_wear:gap_in_vegetation:route_markers`
Applies to:
Definition:	A new key to make it easy to record path status
Statistics:
Rendered as:	variation in symbology for path or footway
Draft started:	2019-05-20

Proposal

This proposal is for a very simple scheme for categorising paths and capturing path status, using one single simple key "path_defined_by"

What forms a 'path' varies greatly, and the differences matter in practice.

Existing attempts to classify or rank paths (and footways) have not been successful, or use very specialist tags covering only very limited circumstances. The idea that objective facts about paths can be mapped in sufficient detail to make it possible to categorise them is unrealistic in the short term (and perhaps the long-term).

Rationale

The problem

Paths vary hugely in character - but current mapping struggles to capture the differences.

There have been various attempts to agree a simple method to categorise or rank paths and path status. Two key proposals were ( pathtype which has seen a very small use, and ( pathtype(alternative) which has not been used at all. There is also the more specialist sac_scale and mtb_scale) which seems successful in only limited circumstances - and in particular is of little use for covering general urban or semi-urban paths or footways.

What people call a 'path' varies hugely. In theory it might be best to record path attributes and to categorise paths according to this data, but in practice this is entirely unrealisitc (at least in the short term). To classify a path adequately it is necessary to take into account at least path width, incline, tilt, variation in tilt/incline, degree of camber, edge quality and character, surface material, surface material grade, surface compactness, surface slipperyness, smoothness, and visibility. Partly issues also arise because paths are used by people with such different needs - whether for example on foot, in small motorised vehicles, on one of many very different bicycle designs, in one of many wheelchair designs, or pushing many different forms of wheeled equipment. This means that it becomes almost impossible to agree on simple definitions of some important characteristics (such as 'smoothness').

The following three images indicate radically different types of path - all which might currently be mapped using the same basic keys and values, so that they will normally be indistinguishable on any rendered map.

	A formal flat urban path/footway
	An urban informal worn narrow steep path
	A marked mountain path with an obvious route but no 'path' actually visible

Proposal to use 'path_defined_by'

It is proposed that we introduce a single new key "path_defined_by".

This should capture very basic information, as below, about what it is which defines the existence of a path. It is proposed that this would, in effect, indicate the relative status of paths, and would provide essential information about the general status of a path and possible or likely challenges in negotiating it.

Initial values for "path_defined_by" would be as in the table below, but additional values would likely emerge in the normal way if these were insufficient. It is proposed that where more than one value was appropriate mappers would be advised to choose only one - using the more commonly used value, or the one which most defined the path:

	full_construction	(path/footway has been built from materials which mean it will last a long time)
	partial_construction	(path/footway was a worn surface, but has had some materials added which help to protect it from further wear, or a fully constructed path which has now broken up).
	worn_line	(path is defined by wear caused by people walking or cycling across the land)
IMAGE-REQUIRED	indistinct_worn_line	(as above, but wear line is difficult to see)
IMAGE-REQUIRED	animal_wear	(path has been created by animals, but is likely to also be used by people)
IMAGE_REQUIRED	gap_in_vegetation	(where trees or bushes or other growth is missing, or has been removed)
IMAGE_REQUIRED	route_markers	(where there is little or nothing indicating the existence of the path, other than markers or signs positioned along its length)

Applies to

Ways: highway=path or highway=footway

Rendering

It is likely that the differences between the status of paths could best be shown using wider/thinner lines, or longer/shorter dashes. Clearly the 'full_construction' and 'partial_construction' values indicate paths which tend to be more obvious and significant, 'wear_line' paths less significant, and 'animal_wear' paths the least significant.

Features/Pages affected

Ways: highway=path or highway=footway

Additional example images

The proposed examples are very broad, so it may be helpful to add some additional images

full_construction
	A path or footway which is fully constructed
	A set of fully constructed paths
partial_construction
	This path is still defined mainly by the wear line created by use and while quite a bit of additional construction supports it (the wall and drainage) it is not a fully constructed path.
	This path has been surfaced in gravel to make it flatter, but is not fully constructed.
worn_line
	A worn path mostly defined by the line on the ground.
	A worn path.
	A worn path.
	Worn paths can vary considerably
	For simplicity the scheme does not distinguish how worn a path is, nor how wide or deep the wear line is.
indistinct_worn_line
	A worn path which is difficult to see.
	It may be difficult to define when a path is 'indistinct' but it is likely that the value will only be used when a mapper notices that the path line is difficult to follow.
	It is obvious immediately before and after this feature that a path exists, but at this location the path itself is only defined by wear on the rocks, foot prints, and damaged vegetation
other
(none)	...