Proposal:Markers subject refinement

Marker plate translating to High pressure gas pipeline underground

Markers indication proposal
Proposal status:	Proposed (under way)
Proposed by:	fanfouer
Tagging:	indication:*=*
Applies to:
Definition:	Addition to existing markers tagging with ability to describe what a given marker is referring to (pipelines, valves, hydrants...)
Statistics:
Draft started:	2023-02-22
RFC start:	2023-04-17

Following Utility markers proposal, it was reported that it's barely possible to clearly state what a given marker is referring to.
It's about distinguishing underground features like pipelines or valves and some distant features like hydrants or even roads as well.

This proposal is intended to introduce minimal necessary tagging to solve this issue and provides a better solution to map markers' indication.
It doesn't change what was previously introduced and only intend to provide an answer to this particular problem.

Proposal

It is proposed the following changes:

• Introduce indication:*=* prefix to designate any feature with the help of existing tagging. Utility markers would particularly use it with indication:man_made=pipeline, indication:power=cable or indication:emergency=fire_hydrant. Further proposals in the future would take advantage of the same prefix to introduce similar keys for other fields.
• Then, update replacement for pipeline=marker with indication:man_made=pipeline
• Deprecate utility=hydrant in favour of utility=water + indication:emergency=fire_hydrant.

pipeline=marker which is currently replaced by marker=* only will be updated to be replaced by marker=* + indication:man_made=pipeline.

This proposal won't challenge pipeline=marker status and it will remain deprecated, as reviewed in marker=* proposal. The vote won't be held about pipeline=marker.
The point is to complete the initial replacement that was reviewed previously.

Rationale

Markers or signs are visual features that indicate the presence of mostly hidden other features. They're not connected to the feature they mark and are mapped as separates nodes in OSM.
Thus, it is necessary to provide a tag to state to which kind of feature they are referring to.

indication:*=* is not used yet and could be defined in general by Prefixes any OpenStreetMap tag designated by remote signage. It is not bound to markers on purpose and could be used more broadly with any signage.
For instance indication:man_made=pipeline or indication:power=cable in utility markers context but also indication:boundary=* or indication:highway=* for boundary or highway milestones and even indication:museum=* or indication:amenity=*.

It has the advantage to reuse any existing OpenStreetMap tagging without duplicating anything.
Available documentation could be used complementary to new prefix without rewriting.

Gather several properties

Furthermore, descriptive information is often written on utility markers or signs to clearly warn of possible danger to anyone passing by them or to state more precisely what the buried infrastructure is useful for.
Then we need a solution broad enough to designate the nature of the feature and record some properties about it that differ from own marker's properties.

For instance, a marker warning about a power cable with its voltage will require two fields to store this information. Indication prefix would work as follow:

• indication:power=cable: A power cable is buried nearby
• indication:voltage=20000: The buried cable operates at 20000 volts.

In the meantime, a marker can get a colour or a reference that would lead to use colour=* or ref=* without any indication:*=*.

Hydrant aren't a proper utility

Markers indicating hydrants are currently tagged with utility=hydrant as per utility markers proposal. However, this value is poorly defined as hydrants aren't an utility sector on their own.
Hydrants are related to emergency features with several methods of operation, including water access from water mains and ponds.

As the actual point of utility=hydrant was to tell this marker refers to a hydrant nearby, this knowledge will be better valuable in the proposed indication:emergency=fire_hydrant. utility=* will be also freed from an unrelated value.

Furthermore, and particularly for hydrants fed from water mains, markers indicating such hydrants could get utility=water as a part of a broader pressurised (mostly drinkable) water infrastructure.

Involve markers in relations

An alternative to proposed tagging would be to involve markers in relations with the feature they mark. A similar practice to addresses and associated street relation.

It would be really complex and hard to maintain. It is chosen to give a try to simpler tagging and lesser usage of relations.

Consistency with boundaries

For consistency sake, it would be legit to cover boundaries in this proposal.
/Using keys like indication:boundary=* would free boundary=* from an unrelated marker value.

Replacement of boundary=marker by indication:boundary=* was studied and appear to be too big to be done now.
This proposal won't review that, despite interesting.

Consistency with highways

highway=milestone could also be covered by this proposal.
Using keys like indication:highway=* would free highway=* from milestones or distance markers.

Several issues still rise about how to document road's ref referred by a given marker and indication:ref=* could be a suitable option.

Replacement of highway=milestone by indication:highway=* was studied and appear to be too big to be done now.
This proposal won't review that, despite interesting.

Tagging

Current marker=* tagging practices don't change.

Proposed indication:*=* would be used in combination with any indicated OpenStreetMap existing tag. Particularly with those for utility markers:

• man_made=pipeline => indication:man_made=pipeline
• power=cable => indication:power=cable
• emergency=fire_hydrant => indication:emergency=fire_hydrant
• pipeline=valve => indication:pipeline=valve

Edition management

Affected pages

• Create indication:*=* as a tagging prefix, add use case for markers and add corresponding values
• Edit pipeline=marker and add indication:man_made=pipeline in replacement.
• Deprecate utility=hydrant and replace it by utility=water + indication:emergency=fire_hydrant.

Tagging to be replaced

Obsolete tag	Usage	Used for?	New tag(s) to use
utility=hydrant	742 on 2025-02-19	A marker referring to a hydrant (underground or not)	utility=water + indication:emergency=fire_hydrant
subject=pipeline	14 259 on 2025-02-28	A marker referring to a gas pipeline (underground or not)	utility=gas + indication:man_made=pipeline

External discussions

• Initial problem reporting on Tagging mailing-list
• RFC announcement on community forum

Examples

Underground features

Photo	Location	Tagging	Note
	France	marker=pedestal indication:man_made=pipeline utility=gas operator=GRTgaz colour=yellow	Such markers are obvious in France and mark buried high pressure gas pipelines. indication:man_made=pipeline is appropriate to clearly indicate the marker marks a pipeline.
	UK	marker=post indication:power=cable utility=power operator=National Grid colour=yellow	As Power cable is written on the marker, we use indication:power=cable here.
	Croatia	marker=pedestal indication:power=cable utility=power colour=white indication:voltage=110000	As Energetski kabel is written on the marker, which translate to power cable so we use indication:power=cable here and additional indication:voltage=110000 to keep track of 110 kV information without energizing the marker itself.
	France	marker=plate indication:emergency=fire_hydrant utility=water operator=Eau de Paris colour=white ref=751120563 position:distance=6.40	This is a typical hydrant marker in Paris.

Voting

Voting hasn't started yet.