> A few years ago, there was an effort (promoted by World Bank, it seems) to > map buildings in OSM for Katmandu where they used key buidling:soft_storey=yes/no. > They never proposed a formal tag. The results of that effort is a bit confusing and I'm not sure it's the best approach.
Because their may not have been very many of these left after multiple earthquakes? Wikipedia isn't probably the most authoritative source on this subject. First, it might be noticed that the term, even in OSM, is not used in isolation, it is part of an extensive internally consistent system of terms from a survey of a particular part of the world. i.e it only helps designates the probability of hazard when all the other factors in that tagging / survey scheme are also noted. 'Soft_storey' is part of a rapid VSM ( Rapid Visual Screening) process ( see Table 3 at https://bit.ly/2S60CE6 for a global list of these, The U.S.A. FEMA https://bit.ly/2QKVhp5 ) In the western United States, designating a building as a 'soft_story' visually with the intended meaning that it was at seismic risk, you would be off base. Many seismic retrofits, especially in historic buildings are invisible. And many with visible mitigation have other characteristics in the coding scheme which make them seriously at risk. The FEMA RVS is 388 pages because the assessment is not trivial. Seismic vulnerability is the sum total of many aspects. > how to map soft story/soft storey buildings properly? Use on of the recognized seismic VSMs that apply to the location. GEM ( https://www.globalquakemodel.org ) is global, and has rapid VSM survey sheets for various countries https://docs.wixstatic.com/ugd/1dcea4_e0c3391c6d32439188f8969ed902f0d6.pdf > Question for the community: does it make sense to add soft story > information using the key building:soft_storey=y/n (similar to > https://wiki.openstreetmap.org/wiki/Key:building:fireproof) or should I use > building:structure=soft_storey? If you intend to give meaningful accurate seismic information, it should be the lowest level concept and only be present if the other characteristics are included, ideally, from a survey. > Good question. For disaster preparedness and response, it is valuable to > have a list of soft story buildings in a neighborhood. There are multiple > places where such buildings are mapped like .... They examples you gave make an interesting point. Who maintains this in OSM, i.e. if a retrofit is accomplished, do you still designate it as soft story? What about addresses which are demo'd and new construction? Also, for various reasons, many, many retrofits are not done under a permit, or not specifically identified as a seismic retrofit. One of those, the city program site, has mostly 'exempt' or 'done' entries, and those appear on the map anyways. Same with the City of SF site, and a quick Streetview of the few non-compliant ones show no residential occupancy, just the ground floor retail is open. For disaster preparedness and response, accurate information is important, in these cases, 'the map' practically useless. However, what I think what you want to do is still possible and could be really, really useful, if it followed a format ( like one of the VSMs) that provided the complete set of characteristics.And those tags should be prefaced with something like 'GEM_soft_story' that makes it clear they are part of a set, not an end conclusion about the building's risk. And you would have to timestamp it some way to refresh it. Michael Patrick ( another kind of soft story https://en.wikipedia.org/wiki/Millennium_Tower_(San_Francisco)#Sinking_and_tilting_problem )
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