[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.


Sergio



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