[HOT] Senegal - Dakar Flooding Activation

nicolas chavent nicolas.chavent at gmail.com
Thu Sep 6 22:42:44 BST 2012


Hey there-

Back from Senegal a couple of days ago and will blog soon around the
TechCamp, the flooding and the status of OSM there

First thanks to all those who contributed to this response: the progresses
of the map are important and your work had a strong impact down there
amongst the TechCamp participants as well as among GISers I met from the
UN, Gov Agency, Academics and Techs. Furthermore it fostered the
remobilization of the nascent Senegalese OSM community by heating things
up.

A few point on this tagging thread.

* highway values most likely to be used and fit for these areas of
Dakar, I'd like to echo Will and others on *residential*, and strongly
support Jaakko's views on *path *(vs footway) which seems well suited for
the most narrow streets. I would refrain when mapping remotely to use
living_street which calls for on-the-ground knowledge and de facto right of
way between vehicle and pedestrians. This is a tag to better explain/
portray and push to the mappers down there. More generally, with Jaakko,
Brian and Sev we feel a need to better articulate guide on using highway
values below tertiary in developing countries.

* surface values: I would use from the imagery *paved/unpaved*, a great
deal of unpaved roads in Pikine and Guediawaye are *sand*

* On the squares/ piazzas, I feel like Harry and would refrain from tagging
them leisure=*pitch/ playground* and/or *parking* since those uses are
really changing over time in the course of the day. Those usages also apply
to a good deal of streets where as a kid, I learned playing street soccer
and hanged out for long hours in wedding/ funerals and later party. I would
then stick to Harry's call: highway=pedestrian and area=yes + drawing roads
(highway=residential) along the edges of the area

* Flooding related tags. I like the work started by Stephane and think that
it would be worth taking advantage of this flooding to solidify and
generate consensus on the tags
In the mapping party we held in Dakar last Saturday, we pushed forward the
following tags to map on the ground the worst hit areas in the view of
building a datasest of flood prone points.
hazard_prone=yes
hazard_type=flood
2012:flood_height=
2009:flood_height=
2007:flood_height=
We will be waiting for satellite imagery processing to get the various
extents (OCHA tasked UNOSAT to carry out such a work with imagery requested
through the Charter)

Again thanks.
Nico

On Wed, Sep 5, 2012 at 10:13 PM, Mike Dupont <jamesmikedupont at googlemail.com
> wrote:

> Ok, we had had a good bootcamp so far, about 70 people, tomorrow we will
> start working on sengal.
> mike
>
>
> On Wed, Sep 5, 2012 at 5:06 PM, william skora <skorasaurus at gmail.com>wrote:
>
>> Hi,
>>
>> Apologies for the delays. Here's some answers to a few questions.
>>  "In some cases of
>> really narrow, hardly visible streets or deep inside a residential
>> area I've used living_street because I assume pedestrians or children
>> playing football use them more often than cars."
>>
>> Regarding the tags of ways, we've done a great job so far, given the
>> ambiguity of the areas, osm tags, and current situation. As most of
>> you have consistently tagged, a majority of the ways as
>> highway=residential (which is appropriate, mostly houses are very
>> small businesses, run out of the home or as a storefront).
>>
>> However, as discussed in the quoted portion and in this picture
>> http://imgur.com/AuNTC - there are a few ways that are not very wide
>> and deserve more consideration.
>> I did a very rough measurement using the measurement plugin and bing
>> imagery, the one in the examples are ~3.5 meters wide, just wide
>> enough for a smaller car or typical taxi. In my experience in dakar
>> for several months, some of these ways still have cars pass through
>> them, although may or may not receive a little less traffic than
>> other, wider streets that are marked as residential . However, there
>> are also many ways, with different levels of visibility on bing
>> imagery, that aren't wide enough for a car to go through, surrounded
>> by residential buildings (likely the best tag for those,
>> highway=footway. When I first started mapping dakar, I tagged the
>> narrow ways as highway=service. In a few cases that I surveyed in
>> person, I've tagged them as highway=footway. In summary, on the ground
>> surveying would provide the context and information that the bing
>> imagery can't provide so I'm not sure what tags would be most
>> appropriate for these narrower ways without on the ground surveying. I
>> hesistate to use highway=living_street
>> http://wiki.openstreetmap.org/wiki/Living_street since there aren't
>> (as far as I know) any traffic laws that categorize these narrower
>> ways than from other residential ways.
>>
>> I spoke to one mapper on the ground in Dakar who told me the
>> areas/ways that Harry mentioned in a conversation a couple days ago
>> are used mostly by kids as play areas; so leisure=pitch ? or
>> playground ? (although there's no equipment ?).
>>
>> Lastly, there are some areas that are more floodprone than others.
>> Personally, I would hesistate for others to tag them ([based solely on
>> bing imagery] and think this may be a job most appropriate to those
>> who are on the ground or have been. What tags have been used ? Any
>> recommended strategies ?
>>
>> Regards,
>> will.
>>
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>
>
>
> --
> James Michael DuPont
> Member of Free Libre Open Source Software Kosova http://flossk.org
>  <http://flossk.org>Saving wikipedia(tm) articles from deletion
> http://SpeedyDeletion.wikia.com
> Contributor FOSM, the CC-BY-SA map of the world http://fosm.org
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>
>
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-- 
Nicolas Chavent
Humanitarian OpenStreetMap Team
http://hot.openstreetmap.org/weblog/
http://wiki.openstreetmap.org/wiki/WikiProject_Haiti
Mobile (Haiti): +509 4617 3334
Mobile (FRA): +33 (0)6 52 40 78 20
Email: nicolas.chavent at hotosm.org
Email: nicolas.chavent at gmail.com
Skype: c_nicolas
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