>> Anyway, for a beginner : is one key even better ? -> should we allow >> “maxspeed=no_sign” ? Or/and “maxspeed=default” ? > > Way too ambiguous to be remotely workable in North America.
Is it? I think what djakk is arguing for, and me as well, is to separate the information stored in "source:maxspeed": -------------------------------------------- 1. Information about whether there is a sign or not (=whether a default speed applies or not) 2. Auxiliary information, if necessary, to automatically infer the speed limit from the given OSM tags. Examples for when no maxspeed sign is in sight: ----------------------------------------------- 1. Motorway in France (FR): highway=motorway + source:maxspeed=FR:motorway vs highway=motorway + maxspeed:signed=no 2. US interstate in Montana (US-MT): highway=motorway + source:maxspeed=US-MT:interstate vs highway=motorway + maxspeed:signed=no + ref~^I (maybe ref-starts-with-"I" is not necessary because all interstates are tagged as motorways?) 3. Road without asphalt or concrete surface in Quebec (CA-QC): source:maxspeed=CA-QC:unpaved vs maxspeed:signed=no + surface!~asphalt|concrete 4. Road with 4 lanes in Delaware (US-DE): source:maxspeed=US-DE:4_laned vs maxspeed:signed=no + lanes=4 5. Urban road in Germany (DE): source:maxspeed=DE:urban vs maxspeed:signed=no + urban=yes etc., you get the idea(?) The tags are just examples. What are the advantages? ------------------------ 1. separating information about the legal road type from whether there is a sign or not a) makes it easier for contributors to supply the latter as they do not have to know precisely about the current speed limit legislation. Good for verifiability. (maxspeed:signed=no --- source:maxspeed=XX:a_legal_category) b) that legal road type (like whether a road is within a built-up area or not) is also an important information, even when an explicit speed limit IS signed. For example to determine the max allowed speed for other vehicle types such as trucks or whether a particular vehicle category is allowed on that kind of road (a_legal_category=yes ---- source:maxspeed=XX:a_legal_category) 2. using existent tags (e.g. surface, lanes,...) a) removes duplicated information (lanes=4 --- source:maxspeed=XX:4_laned) b) tries to avoid as much as possible "legal road type" categories, as these, like default speed limits, may change anytime and have problems with on-the-ground verifiability. Thus: better future- proofing. (source:maxspeed=AT:living_street does actually not exist anymore since legislation change in 2002) 3. removes superfluous country ISO-code. Country boundaries information is already available in the OSM database, data users can just use a (reverse) geocoder to find where a street is. (I wrote Java library recently that does this offline in ~0.1ms) (Ask me for concrete examples) On 19/09/2018 17:44, Paul Johnson wrote: > > > On Wed, Sep 19, 2018, 10:22 djakk djakk <djakk.dj...@gmail.com > <mailto:djakk.dj...@gmail.com>> wrote: > > Yes Paul, I should not forget the beginners ... > > I am not a beginner anymore but I still found “source:maxspeed=“ for > roads a little confusing, as we should use “source=“ only (?) on the > metadata (on the changeset). > > > Specific keys that don't change often and have verifiable source can > also have source keys, this would be a good example of that being > appropriate. > > Anyway, for a beginner : is one key even better ? -> should we allow > “maxspeed=no_sign” ? Or/and “maxspeed=default” ? > > > Way too ambiguous to be remotely workable in North America. > > > > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging