Proposal:Defensive structures

Proposal

This proposal introduces defensive_works=* to tag individual defensive structures mainly at historic/pre-modern  fortifications. It is intended for all structures that were built for the defence of territories in warfare. This includes fortified settlements as well as forts that are/were uninhabited during peacetime.

Values for defensive_works=* contain terms used in fortification engineering (see #Tagging).

defensive_works=* is intended to be used in combination with existing tags. Although it may technically make a few existing tags redundant, no deprecation of any tag is proposed and mappers are encouraged to use existing tags and defensive_works=* in conjunction.

Rationale

Although fortifications are a common sight in many parts of the world, the structures that shape them still lack a dedicated tagging scheme in OpenStreetMap. Some structures are mistagged to achieve rendering ^(example) and many others are currently not tagged at all.

The proposed tagging scheme provides new possibilities to tag named defensive structures, which often have historic value and may even be cultural heritage sites. Having notable historic value is, however, not a requirement for the use of defensive_works=*.

How to map

Individual defensive works should be mapped as Nodes at their centre, as Ways along a centre line or as Areas along the outlines. The best fitting method depends on the size and shape of the structure. They should be tagged with defensive_works=* and may receive additional tags.

Tagging

The following tags for defensive structures are proposed:

Tags to use in combination

• name=* - if a defensive structure is named. Do not use the name of the fortification to tag individual structures.
• heritage=* - if the structure has a heritage status. If only the entire fortification has a heritage status, do not use heritage tags for individual structures.
• building=bunker - if the structure is a  bunker
• start_date=* - year of completion
• abandoned=yes - if the structure has been abandoned and shows signs of decay
• disused=yes - if the structure is disused
• ruins=yes - if the structure is in ruins

Examples

The examples below serve to illustrate how a defensive_works=* tag can be used along other tags. Please keep in mind that neither the current nor the proposed tagging combinations are definitive.

barrier=city_wall and historic=citywalls may be considered redundant in this case, as the counterguard is part of Fort Ricasoli rather than any city.

The proposal author advises against the use of historic=castle and castle_type=fortress here. The ravelin is only a part of a larger fortification, and adding these tags to it may give the impression that there are multiple fortresses instead of one.

This feature may be integrated into the Cartagena City Walls.

Diagrams

Features/Pages affected

Similar and related tags

• barrier=city_wall
• barrier=sally_port
• barrier=tank_trap
• bunker_type=*
• fortification_type=* (some rare values)
• historic=cannon
• historic=castle_wall
• historic=city_gate
• historic=citywalls
• military=trench
• tower:type=defensive
• wall=castle_wall
• water=moat

External discussions

• 2021-07-02, OpenStreetMap World Discord server: Announcement in the #proposals channel
• 2021-07-06, Dutch forum: Tagging voorstel voor fortificaties
• 2021-07-06, Tagging mailing list: Feature Proposal – RFC – defensive structures
• 2021-11-10, OpenStreetMap World Discord server: Announcement in the #proposals channel
• 2021-11-10, Tagging mailing list: Feature Proposal – RFC – defensive works
• 2022-01-04, Tagging mailing list: Feature Proposal - Voting - defensive_works=*

Voting

• I approve this proposal. --501ghost (talk) 12:00, 4 January 2022 (UTC)
• I approve this proposal. --Zaneo (talk) 12:07, 4 January 2022 (UTC)
• I approve this proposal. --JeroenHoek (talk) 12:47, 4 January 2022 (UTC)
• I approve this proposal. --Endim8 (talk) 14:21, 4 January 2022 (UTC)
• I approve this proposal. Probably the best, most detailed and thought-through proposal I have ever seen, at least big tables. --Emilius123 (talk) 15:35, 4 January 2022 (UTC)
• I approve this proposal. --Riiga (talk) 20:22, 4 January 2022 (UTC)
• I approve this proposal. --Fizzie41 (talk) 22:20, 4 January 2022 (UTC)
• I approve this proposal. ---- Kovposch (talk) 10:53, 5 January 2022 (UTC)
• I approve this proposal. --O0235 (talk) 12:19, 5 January 2022 (UTC)
• I approve this proposal. — AlephNull (talk) 13:21, 5 January 2022 (UTC)
• I approve this proposal. --ZeLonewolf (talk) 13:27, 5 January 2022 (UTC)
• I approve this proposal. --Pantufla (talk) 14:28, 5 January 2022 (UTC)
• I approve this proposal. --Dr Centerline (talk) 23:15, 5 January 2022 (UTC)
• I oppose this proposal. The proposal is weirdly ambiguous on if this is introducing a new top level tag or if this is simply an attribute to add to existing objects. If this is the former it would be better embedded in an existing hierarchy for example man_made=defensive_works, defensive_works=..... In general I'll oppose all proposals that do not cover the basics, in particular because introducing new top level tagging creates a large amount of churn and in general is rarely of benefit to the project. --SimonPoole (talk) 14:50, 6 January 2022 (UTC)

Hi SimonPoole. As I've written in #How to map, a man_made=defensive_works tag is not being proposed, and other additional tags are generally optional. Although defensive works are man-made structures by definition, I have chosen to propose them in a separate key, as fortification engineering is a broad and distinct topic that has very little overlap with existing main feature tags. I also didn't classify defensive structures as historic=* objects, because not all of them have notable historic value. If you have any further questions or comments, please add them to the discussion page. --501ghost (talk) 15:22, 6 January 2022 (UTC)

So, to be clear, you are proposing a new top level tag. I don't believe the argument with respect to "historic" is valid, there is no requirement for objects mapped that way to be of wider significance. So for example historic=defensive_works for historic facilities and military=defensive_works for such that are still in use would make a lot more sense than introducing new top level objects.

I have thought about historic=defensive_works and military=defensive_works as main tags, but this would have led to a redundant duplication of defensive_works tags and is not always applicable, for example for defensive works operated by organisations outside the military. As you say, I have instead opted to use the defensive_works=* key itself as the way to categorise the different tags. --501ghost (talk) 15:42, 6 January 2022 (UTC)

Final note using an existing object hierarchy, instead of unnecessarily creating a new one at least gives you a certain chance of the tagging being supported at least a bit, doing your own thing just means it is going to be widely ignored. SimonPoole (talk) 23:52, 8 January 2022 (UTC)

• I approve this proposal. --EneaSuper (talk) 11:31, 9 January 2022 (UTC)
• I oppose this proposal. In my opinion, mapping such structure in current conflict zones shouldn't be encouraged, therefore it should be made clear from start (and top tag) that this is intended for historical context only. Beyond that, thank you for the detailed documentation. --Claire Halleux (talk) 11:47, 9 January 2022 (UTC)

Would adding Template:Mapping Military Sites to related pages solve this issue for you? --501ghost (talk) 16:07, 9 January 2022 (UTC)

• I have comments but abstain from voting on this proposal. Described as not needing to be historic, but no modern examples given. Perhaps fortification_type=* could be expanded? --Loshu (talk) 12:53, 9 January 2022 (UTC)

As I read it, historic=* is intended for objects with notable historic value, which is not always the case for individual structures within a larger fortification. I decided against using fortification_type=* as it is a sub-tag of historic=archaeological_site, which is rarely applicable for defensive works. --501ghost (talk) 16:07, 9 January 2022 (UTC)

• I have comments but abstain from voting on this proposal. Have not reviewed it, and while mapping modern military installation can be tricky and problematic it is not something that should be generally forbidden (for example see mapping clearly visible things around Korean Demilitarized Zone). Though historic=* in practice is not only for ones with significant or notable historical value. --Mateusz Konieczny (talk) 13:28, 9 January 2022 (UTC)
• I approve this proposal. --AntMadeira (talk) 13:33, 9 January 2022 (UTC)
• I approve this proposal. --Reino Baptista (talk) 19:09, 9 January 2022 (UTC)
• I have comments but abstain from voting on this proposal. I'm mostly fine with this, but I do think there should always be a top level tag, whether it's a building (i.e. building=bunker), a barrier (barrier=city_wall), or man_made/historic/military=defensive_works (maybe grouping objects together in a relation?) --Famlam (talk) 09:52, 11 January 2022 (UTC)
• I approve this proposal. This is extremely well planned. I think this might encourage mapping of this type of things in areas of conflict wich I think is good especially when it is on an open map for everyone to see. --Aaro Hart (talk) 21:28, 17 January 2022 (UTC)
• I approve this proposal. Is a proper solution to add details to these structures. Fits other tagging schemes where specific tags can add additional information to more then just a single top level tag. Well done.--Bert Araali (talk) 12:21, 18 January 2022 (UTC)

References