[Tagging] Feature proposal - RFC - Line attachments

Sergio Manzi smz at smz.it
Sat Mar 9 18:21:15 UTC 2019

On 2019-03-08 00:35, François Lacombe wrote:

> Hi all
> The line attachments proposal has been updated according to comments received all along past weeks. Thanks to TOGA and Nakaner mainly.
> https://wiki.openstreetmap.org/wiki/Proposed_features/Lines_clamps
> It is not restricted to power nor telecom lines. Any line can be anchored or held with suspension clamps over heads.
> This sounds to be ok for me and may be voted shortly.
> Feel free to raise objections or comments prior of this to help building a more useful tagging.
> All the best
> François

I already expressed my dissent about using OSM for mapping/tagging this kind of things on the ground of both A) this not being matter for a *Geografica**l* Information System, and B) the technical limitation of OSM architecture for storing such information, I therefore will not insist on this point any more.


I've read your proposal and IMO it contains so many mistakes to make it unfit to be taken into consideration even as a starting point:


*A) **Scope of the proposal.*

It is badly defined. The "Definition" is given as "/Consistently defining how a power, telecom or even washing line is attached to supporting pole or tower/", a very broad definition, but then reading on I see that you state that "/This proposal is mainly dedicated for utilities network//s/". Which one should we take? With the "mainly" adjective are you indicating that you are willing to extend the scope of the proposal to different application fields later on?

As a matter of fact I'm convinced that a generalization cannot be done in terms of tagging: "attaching" a power line to a fixed infrastructure is done with very different techniques from the "attaching" of a washing line, the suspension line of a cable car, the cables of a suspension bridge, the overhead line of an electric railway (/and I have the strong feeling tha "railways taggers" here have their own ideas on how to tag their contact lines/), etc., and therefore will require different tagging schemes.

*B) **Inconsistency between the proposal name and the tag name.*

The proposal is named "Line clamps", but then the tagging is defined as "line_attachment". This is confusing.

*C) **Are we really talking about "Clamps"?*

A "/clamp/" is a device or a tool used to fix two otherwise relatively moving parts to each other by virtue of friction and compression (/which augment friction/).

In a power line a clamp is just the device used to fit the conductor to the insulator. The definition given by  IEC 466-11-09 and 466-11-10, that you are referring to, are clear: "/a fitting which attaches a conductor to a _suspension insulator set_/" and "/a clamp which attaches a conductor to a _tension insulator set_ or to a support, and designed to withstand the conductor tension/". In the IEC documentation both are tagged to be in the "Conductor fittings" of the "Overhead lines" area of the IEC.

IEC 383-2 (/Insulators for overhead lines with a nominal voltage above 1000V/) gives definitions:

  * *Insulator string*: One or more string connected insulators units and intended to give flexible support to overhead line conductors and stressed mainly in tension.
  * *Insulator set*: An assembly of one or more insulator strings suitably connected together, complete with fixing and protective devices as required in service.
  * *Suspension insulator set*: An insulator set complete with fittings to carry a line conductor or conductors at its lower end.
  * *Tension insulator set*: An insulator set complete with fittings to secure a line conductor or conductors in tension.

The images you are attaching to the definition of "suspension_clamp" and "anchor_clamp" are misleading in the sense that one could easily take what in reality is a "Suspension insulator set" as a "Suspension clamp" and a "Tension insulator set" as an "anchor clamp".

The confusion is even more augmented by the fact that in your proposal you refer to "shackle insulators" too (IEC 471-03-09), and they are in a totally different area of the IEC standards, "Insulators", same as "pin insulators" (IEC 471-03-06).

So, are we talking about clamps (fittings) or about insulators (/or insulator sets/) here? Because it really seemsyou are mixing under the same tag two very different kind of objects...

Are you taking "a clamp" as "the whole thing suspending conductors from the tower/pole" (/of which the insulator is just a component/)? That would be a mistake: that's an "insulator set", not a clamp. And BTW, how could you then tag "the real clamp" with its bolts and nuts when it comes to it?

*D) Inaccurate wording. *Some examples:

  * You state that "anchor_clamp" is "/built stronger than suspension tower//s/". Really? A clamp stronger than a tower? :-/
  * "/A shackle insulator may be used to hold conductors safely from their support/" Isn't that the meaning of the life of *every* insulator?
  * ...


*E) Logical mishaps*

In "Complex configuration", under the image of a pole with two levels of conductors (/3 on the higher plane, 1 below "on the right"//watching the image/), you state that "/Values would go _from right to lef_//_t_ / top to down of the pole while values in each section would be given _from left to right_ in the direction of the way passing by the support node/". I _really_ don't understand what you are trying to say. Sorry for asking, but right and left wouldn't just swap if I watch the pole from the opposite side? (/and yes, as others already pointed out, semicolons have a different meaning in OSM tagging/)

... I have to admit that at this point I stopped reading.


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