Proposal:Hazard warning

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Hazard warning
Proposal status: Obsoleted (inactive)
Proposed by: Nop
Tagging: hazard=*
Applies to: node,way,area
Definition: Marks a location potentially dangerous to travellers

Rendered as: caution traffic sign
Draft started: 2008-11-10
RFC start: 2008-11-29


Introduce a tag to mark dangerous locations on a way that require a traveler to pass with caution. This is intended for the dangers encountered by hikers and cyclists on smaller tracks and paths in the countryside as well as street hazards marked with a traffic sign.

Optionally, the exact nature of a hazard marked by a traffic sign may be illustrated by adding a reference to that traffic sign.

Dangers on roads

Dangers on roads are usually marked with a traffic sign, but warnings about existing dangers without a posted signs are of interest, too. Only specific warnings should be mapped, e.g. animal crossing, but not the generic caution traffic sign that does not state a reason.

Dangers on paths and tracks

These dangers are usually not marked at all. Examples I have encountered and would like to warn others about include:

  • Holes or overgrown ditches in the middle of the track
  • very narrow paths with electrical fences on one or both sides
  • wire and barbed wire on the ground on or next to the path
  • broken barbed wire fences leaning into the path

The tag is intended for permanent or long-time hazards. Many of the above dangers obviously have been resting in the woods for years. Short-Time obstacles (e.g. fallen trees) that are likely to be cleared soon should not be mapped.

It should be used to mark unexpected hazards on an otherwise harmless track. You should not map every steep drop on a way that is already tagged as an alpine hiking trail.


When you know about the existence of dangers on a trail, you can progress with caution and avoid accidents. When traveling with children or dogs you may decide to avoid a way altogether and go for an alternate route. A tag like this fulfills the same warning role as the "Caution" traffic sign.

The meaning of this could be conveyed by different terms already in use. Here's an overview of the European tagwatch statistics for these keys.

Tags Description










rradius of bend im metres

when some lanes are narrower than others ( example )


As a majority of these tags are using hazard and a free-form value I am adapting my proposal correspondingly to use hazard=*. The variety of possible hazards encountered is too great to limit them to a predefined list, so a free-form value is proposed.

Discussion has brought up the interest in a means to exactly tag hazards if possible. Tagwatch shows that the tag "traffic_sign" is already in widespread use (more than 5500 instances) with a wide variety of values. Therefore I propose to use traffic_sign=* in conjunction with hazard=* and a list of predefined values. Traffic signs are referenced by predefined values rather than sign numbers e.g. from the German traffic rules. Those are exact, but only meaningful in Germany while a defined value can be readily understood and rendered according to local needs. In the context of this proposal, predefined values are provided for warnings that are not redundant with information already displayed in the map or handled by seperate tags. E.g. there are signs for sharp turns, but as you can see the sharp turn on the map, there is no need for it. Inclines are marked by a seperate tag and are visible in contour lines if available, so there should be no extra sign for them.

The proposals for hazard=* and traffic_sign=* shall be discussed and voted seperately.


Hazard warning:

hazard=nature of hazard

The value contains a descriptive text with the nature of the hazard. The text should be expressed very briefly so it is feasible to render it in detail maps.


Traffic signs:

If there is a traffic sign or you want to exactly define the nature of the hazard, use traffic_sign=*, either alone or in conjunction with hazard=yes

Suggested definitions for value are:

  • animals_crossing (edited while "Abandoned" status: instead of hazard=animals_crossing please see also hazard=animal_crossing
  • falling_rocks
  • slippery_when_wet
  • icy_road
  • crosswinds
  • steep incline
  • junction (see [1])
  • children ([2])
  • cyclists ([3])
  • skiers ([4])
  • cattle ([5])



Applies to

Nodes if the danger is on one location. Ways if the danger concerns a stretch of a way.


Similar to caution traffic sign, Value text shown as name on very low zoom levels.

e.g. [6] [7] [8] [9] [10]

See also


Please use discussion page to comment.