[Imports] WRI Congo Basin forestry tracks import

Christoph Hormann chris_hormann at gmx.de
Tue Feb 17 14:57:14 UTC 2015


On Tuesday 17 February 2015, Thomas Maschler wrote:
>
> I added a link to the wiki for a technical documentation of origin,
> production process and accuracy assessment. Find the link also below,
> for your convenience.
> https://wri-forest-atlas.s3.amazonaws.com/Team/Projects/OSM/cmr_roads
>_technical_report.pdf

Thanks for that - this clarifies a lot of things.

Based on this the primary source is Landsat Imagery from 1999-2003.  
That implies a number of things:

- Under the circumstances here, i.e. with a strucured landcover, it is 
impossible to identify a highway=track on Landsat images.  
- What is actually mapped therefore are clearings in the forest.  These 
would normally be tagged man_made=cutline.  It is of course safe to 
assume that in the center of a longer line clearing there is a road at 
the time the clearing is cut which is usually a highway=track.  But 
this already involves quite a lot of guesswork.

Add to that the fact that the data basis is 10-15 years old meaning that 
unless the tracks have been used and maintained for a different purpose 
than logging (which would make them something different than 
highway=track in most cases) they probably have decayed and grown over 
again since that time, especially if the clearing visible on the 
Landsat image that was the basis of the mapping was already several 
years old when the image was taken (leading to a possible total age of 
20+ years.)

My recommendation therefore would be to not use this data for an import 
but render a map layer from it that can be used as a hint by the 
mappers in the sense of 'look for a road here and if there is one map 
it based newer high resolution images'.  

> Logging roads are inside logging concessions or logging titles and
> access is granted to logging companies only. Often, roads are blocked
> once abandoned. However, law is not always enforced and even if
> blocked, roads are still used by motorbikes and pedestrians to access
> the area.
>
> Plantation roads inside plantations are private as well.

If the roads are within privately owned/leased land and the owner 
forbids access to the general public the correct tagging would be 
access=private.  access=forestry is for public roads that are limited 
to forestry use by a public authority.  But since you speak of logging 
concessions i would assume neither is the case, i.e. this is normally 
public land where logging rights are given exclusively to some company 
but other uses of the land and roads are not generally restricted 
unless specifc restrictions for other reasons exist locally.

> All logging road are unpaved. We didn't include this attribute in
> most of the layers, because it was a given. Material depends on the
> local situation. Mostly it is laterite, but it could also be rocks,
> sand etc. Unpaved would be the most appropriate tag. However, if you
> say, track tag already assumes, that the road is unpaved, we can
> discard the surface tag.

That would be a good idea.


-- 
Christoph Hormann
http://www.imagico.de/



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