Prominent danger warnings

What is the best way to indicate something is dangerous but may look undangerous to people, as opposed to something people will realise is dangerous. An example is an established path across a wide estuary where you need to go at the right time otherwise the water will rise as you walk across and it will turn to quicksand.
I’ve seen people put the warning in the name title which although is not ideal as the name is searched it may be a practical thing to do so that it is seen, given there aren’t many instances of it being needed in areas people will otherwise think things are safe (for example it’s obvious there are going to be dangerous spots on Everest).
Is there an existing mechanism for doing this? if not, could there be one - for example, you could have a designated trigger sequence in the name so that searches will know how to split it e.g. if the symbol were Danger! then you could have “Innocent Path (Danger! check tides)” and name searches would just search the name part (Innocent Path), but a visual map would render the whole name entry. Or you could have a separate tag that achieved this with the possibility that some renders wouldn’t render it…

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Many thanks - but does it allow the rendering of a custom warning visible to the viewer?

OSM is just the database. If a feature will be visible on a map you need to ask the one who creates the map. On Mapnik (the example map on it doesn’t get rendered (overpass turbo).

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Yes, this is the problem. Much as it’s a database, the very nature of a hazard is that it’s critical to display and something custom is often needed - a few stock concepts is often not going to be sufficient. It’s why I think to operate in the real world there should be some agreed trigger sequence usable in the name, and renderers and other utilisers can extract it from the name if they choose to and show it in some custom fashion.

OSM is open data, by its very nature it is not possible to impose any constraints outside of the licence, respectively the open definition, on downstream users.

We can, and have done, for example for interpretation of access tagging, indicated what best practice should be, but that is by its very nature not binding and the limit of what we can do with respect to downstream data users.

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Taginfo shows that only a few data consumers currently understand hazard=*, mostly editing software, but I see OsmAnd listed in there as supporting a handful of specific hazard=* values. OsmAnd is a popular mobile navigation application.

Since you have a good idea of what the user experience should be for this information, you could directly ask the developers of OSM-based renderers and navigation software to consider implementing it, or even contribute that functionality if you’re able.

For example, here’s a request for something like you’re describing in Organic Maps, another popular mobile navigation application:

Here’s an old ticket tracking some ideas for avoiding hazards in OSRM, one of the original OSM-based routing engines. Although OSRM itself isn’t a consumer-facing application, many services, including, rely on it to generate routes:


In some very extreme cases, local communities have agreed that historic “paths” should be hidden, e.g. across estuaries
Way: ‪Leven Estuary Crossing (Warning. Public Rights of Way across Leven Sands are dangerous. Seek local Guidance… See Note)‬ (‪1187913110‬) | OpenStreetMap

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