Hi Ilya, Am 2017-09-24 um 10:49 schrieb Ilya Zverev: > I had a task of extracting subway infrastructure from OpenStreetMap, and > I found out that some things cannot be mapped at all (e.g. > interchanges), and some are unclear or mapped differently in different > countries. > > Please consider this proposal that clarifies tagging and mapping of > subway stations: > > https://wiki.openstreetmap.org/wiki/Proposed_features/Metro_Mapping
I don't understand what's the aim of your "proposal". There are almost no new tags. Is it intended as a write-up of what could and should be mapped and tagged and how that should happen? It is a good write-up, it gives a good overview but does not answer the questions of the differences between railway=subway, railway=train, railway=light_rail and railway=tram. I am not against a long and structured write-up for mapping public transport but I would prefer if people would invest the time into cleaning up existing pages on the wiki. There is already an overview page: https://wiki.openstreetmap.org/wiki/Public_transport I started cleaning it up (based on the German version which was cleaned up and reviewed more than a year ago). > I have already started improving the mapping of several metro systems in > different cities. Mostly that involves adding stop_area and > stop_area_group relations. I thought that stop_area_group is a dead branch of the "Oxomoa" public transport tagging scheme which influenced the current tagging scheme (I prefer the term PTv2 – Public Transport version 2 – for it), isn't it? > Adhering to this document would greatly simplify using subway data from > OpenStreetMap in applications — both for multi-modal routing and for > formatting pretty schemes. That's a goal everyone had who wrote a tagging guide or proposal for public transport. The key problem is a lack of guidance by tools using the data. While other topics have lots of map styles/routing engines and quality assurance tools, public transport has only very few tools which are up to date and still maintained. (I currently work on public transport validator) https://wiki.osm.org/wiki/Proposed_features/Metro_Mapping writes: > If you know the location and length of a platform for a subway station, map > it as a way Way. Using a node is pretty meaningless, and drawing a platform > as an area is an overkill, though possible. You can see an example of such > thoroughly drawn platforms here. A way is better than nothing but if a mapper is able to draw an area because the station is pretty simple or he used a laser distance meter [1], this should not hinder him to draw an area. https://wiki.osm.org/wiki/Proposed_features/Metro_Mapping writes: > The modern public transport tagging schema introduces stop positions: points > on rails where trains actually stop. These should be placed in the middle of > a hypothetical train, that is, near the center of the platform. Adding them always near the centre of the platform is wrong and useless. A machine could that do, too. From my point of view they should be added where the centre of the train is. If a platform is three MU long but trains are only three MU long during peak hours and short trains stop near one end of the platform, the stop position node should be located where the centre of the shortest train will be. Many train, tram, subway and light rail systems have signs in the track or along the track which tell the driver where to stop depending on the length of his train. This signs can also be used by mappers and passengers who know how to interpret them. https://wiki.osm.org/wiki/Proposed_features/Metro_Mapping writes: > When it is possible to go from a station to another station without leaving > the metro system, that is, without passing a railway=subway_entrance node, > these stations are considered to be in an interchange. To mark it, create a > public_transport=stop_area_group relation, and add stop_area relations (not > station nodes!) of all stations that are part of the interchange. I am not a fan of stop_area_group relations. They tend to be collective relations (like stop area relations). The practical use of stop_area_group relations is limited. Classic public transport routing engines need a manually produced set of "virtual" connections between two stations which are within a walkable distance, e.g. from Weinheim(Bergstraße) to Weinheim Hbf [2] because they only calculate routes based on the timetable. Nowadays multi-modal public transport routing engines are available, even as open source software. That's why I think that any suggestions for interchanges should not be mapped. It is a problem which solveable by a computer programme. Suggestions are non-factual information which do not fit into the goals of OpenStreetMap which is based on facts. Best regards Michael [1] https://youtu.be/5T5zH-zanXI?t=10m48s [2] https://www.openstreetmap.org/#map=17/49.55290/8.66625 -- Per E-Mail kommuniziere ich bevorzugt GPG-verschlüsselt. (Mailinglisten ausgenommen) I prefer GPG encryption of emails. (does not apply on mailing lists)
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