Pierre's suggestions are a good guideline in general and I don't have any disagreements with them.
I did, however want to expand a bit on the idea of when to use service roads, so here is that... I for one am in favor of additionally making liberal (but careful) use of highway=service. A service road is like a residential road, but is not meant to be used for "through traffic" but rather as the first or last leg of a longer journey. With this in mind, I offer up the following example as a good guideline (or case study) of how this should look in practice: Several years ago, I traced the roads in Ibadan, Nigeria. It was nearly a blank map when I started so I had complete freedom in deciding how to classify them (this was years before "highway tag africa"). I started by just marking nearly everything as highway=residential. Then after the whole city was mapped I spend some time just looking at the finished map and the roads overlaid on the satellite imagery. After taking in this "whole city view" for a while I began to see patterns in how the roads were laid out, and these patterns suggested which roads should be downgraded to service. In the case of Ibadan there are little "pocket communities" of people, separated by streams with a few roads crossing the streams but a dense network within each community. So after digesting the map, and seeing how the town was structured, I decided I would downgrade all the roads that only served to access buildings within one community, but were not part of the routing if you were traveling outside of the community. This lead to a marked improvement in the quality of the map, which you can see in the two links below. Although I finished tracing all the roads, I didn't finish all the classifications, so you can see a good "before and after" of how much better it looks with proper use of service roads. Here is a "before" section where all the roads are left as residential: https://www.openstreetmap.org/#map=15/7.3354/3.9118 And here is an "after" section where I have downgraded local-access-only roads to service but left the rest as residential. Notice how much more clearly you can see the neighborhoods, and also how much easier it is to follow a route, without having to use a route planning tool. You can navigate just by looking at the map. https://www.openstreetmap.org/#map=15/7.3933/3.9598 In the second example above you can actually see some areas of all residential to the east, so there is a very clear difference between the two sections. Obviously every town will be slightly different, but I think this is the general rule we should follow: if you use the road mainly for accessing buildings (even if it is a fairly large number of them) but not for long distance travel, then the road should be downgraded to service. After you spend a bit of time looking at the whole town, and keeping this rule in mind, you will get a good sense of what to downgrade. Then it is just a matter of going through and applying it. Anyway, hope this all makes sense to people. I had been meaning to write it up for a while now and this seemed like a good opportunity. Maybe I will try to go through and finish up Ibadan, I am a lot faster at this now than I was back then, so it wouldn't take me long. I will leave it for the time being so it doesn't break the examples. If people think this sounds reasonable, maybe we should grab some before and after screenshots for the wiki to document this. -AndrewBuck On 11/14/2017 03:30 PM, john whelan wrote: > That seems very sensible. > > Thanks John > > On 14 November 2017 at 16:26, Pierre Béland <pierz...@yahoo.fr> wrote: > >> I we follow the Highway Tag Africa wiki page I initiated in 2013, narrow >> highways should be evaluaed on the type of traffic possible >> - highway= residential in residential areas if at least passable by 4 >> wheels >> - highway=path if only motorcycles, bicyles and foot traffic is possible. >> >> https://wiki.openstreetmap.org/wiki/Highway_Tag_Africa >> >> The additions made to the wiki page a few months ago about the width add >> confusion. I think that we should simply move this in a separate section >> giving guidance on possible widths that represent the various types of >> highways. >> >> regard >> >> Pierre >> >> >> Le mardi 14 novembre 2017 16:14:22 HNE, john whelan <jwhelan0...@gmail.com> >> a écrit : >> >> >> I'm not even sure if this is the best place to raise this but Africa >> covers a lot of countries. >> >> We have some agreement on how to map highways in general Africa but narrow >> residential highways are a problem. I suspect highway=residential plus a >> width tag might be best. >> >> South Africa I think has local mappers who able to resolve any problems >> but for the rest of Africa given the large number of armchair mappers >> mapping there some guidance would be nice. >> >> Some mappers use highway=service generously. >> >> Is it possible to reach some sort of general concenus? >> >> Thoughts? >> >> Thanks John >> _______________________________________________ >> talk mailing list >> talk@openstreetmap.org >> https://lists.openstreetmap.org/listinfo/talk >> > > > > _______________________________________________ > talk mailing list > talk@openstreetmap.org > https://lists.openstreetmap.org/listinfo/talk >
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