60 - 230 kV lines on tubular steel poles
I think the SMUD 230 kV line would belong to the last category as it is not immediate obvious whether the supports should be tagged as towers or poles. They have the shape of a pole but the height of a tower.
I added another picture with various examples (location). Three dual-circuit powerlines (230, 115 and 60 kV) are raised on tall tubular steel poles to cross over an intersection of major streets (the 12 kV minor line goes under the streets). Behind the camera, the 115 and 60 kV lines continue on simple wooden poles (the 115 kV line splits into two parallel single-circuit lines here). The wooden poles would obviously be tagged as power=pole though the lines are bigger than minor (someone has suggested 42 kV as a limit between power=line and power=minor_line).
I suggest the distinction between power=tower and power=pole be based on the shape, size and/or material of the structure itself (node), while voltage is a property of the powerline (way); moreover, voltage cannot usually be observed directly.
T99 19:11, 16 February 2011 (UTC)
- I'm so far confident, that with enough pictures it should become obvious that at least the point of tubular vs. lattice can't be a decisive criteria. But we'll see when we get more pictures. Apparently, so far, there's two different cases where users can come to different conclusion, and they're vary between countries: unconventionally shaped structures from Europe, which carry something between 20-66 kV lines, and your NA example of high voltage lines where the structure "looks like pole" but is in size and function similar to the typical power=tower (insert a proverb about how things are always bigger in USA). Alv 08:32, 17 February 2011 (UTC)
I added some new examples, including the base of a huge "pole" (next to a small excavator for size comparision). That particular pole is at 38.8237, -121.5255 where the new power line (under construction in former Sacramento Northern Railway right-of-way) crosses Howsley Road. You can see poles at various states of construction in some brand new "satellite" imagery at Google Maps. I'll have to wait until the next Bing, NAIP or USGS Ortho imegery update before tracing the rest of the line.
T99 03:13, 17 April 2011 (BST)
- Which are definitively power=tower. They carry a power=line, and they're similar in size, and have similar technical properties as the obvious cases of power=tower - the fact that they're not steel lattice is irrelevant. Alv 12:13, 17 April 2011 (BST)
- How could we define the distinction formally? I was going to suggest something along these lines: "Jos rakennelma on pohjasta avoin ja niin suuri, että sen alta mahtuu hiihtämään selkä suorana, silloin kyseessä on power=tower, muutoin power=pole." How would we add voltage to the equation? T99 18:26, 17 April 2011 (BST)
- Where on earth did cross country skiing come into this? And no, mostly the two legged poles have room to ski under the |\ bit, like the one in File:Powerpole-A-leaning01.png. So far we haven't seen anything 60 kV or higher on what would be power=pole, although there's one example that might be: the very rightmost construction visible in File:Powerlines4.jpg. The second structure from right would also be hard to classify: in that photo it looks like it's significantly smaller than the next one with both high voltage lines on the same tower. The difficulty for both rightmost structures is partially the result of their surroundings not being that visible in the photo. Alv 08:23, 19 April 2011 (BST)
- The 60 kV line in File:Polematl.jpg uses quite ordinary wooden poles, along with steel poles of the same size where additional lateral strength is required. I'll see if I already have a better picture; if not, I'll go and snap one (there are plenty of small 60 kV lines here and 69 kV lines just across the county line). Also, the 115 kV line in File:Powerlines4.jpg (sorry, the picture is too busy) has many wooden poles that are only slightly larger in size.
- The distinction between waterway=river and waterway=stream is based on whether one can jump across it or not. We could find some equally creative method to gauge tower/pole sizes in the field. Alternatively, we could assign some arbitrary thresholds based on strictly physical measurements. - T99 19:03, 19 April 2011 (BST)
- The logo on the wall reminds me of the reality show "Hell's Kitchen". :-) Some of the older lines to the south are apparently those "gemensamma 620 kV" lines that Hufvudstadsbladet so expertly wrote about when they were new. They need to write a new article about all of the 1130 kV out there today! It might be interesting to know which city operates which line.
- I'll post a picture of a simple wooden pole in the 115 kV line mentioned earlier. The length of the insulators implies a 115 kV rating. The line used to be operated at 60 kV. I initially thought it was upgraded to 115 kV recently, but the state has published some environmental documentation about the upgrade of an adjoining line which implies that the actual operating voltage of this line may not have been raised yet. (For fear of industrial espionage or sabotage, PG&E and other private or public power companies do not want to publish any technical details of their networks, but luckily the environmental impacts of any proposed new construction have to be documented. The difficulty of determining voltages suggests that we should classify structures by observable mechanical characteristics only.)
- We could refine the definition of power=pole by requiring that the majority of the weight of the structure and the cables is borne by a single vertical column with a limited circumference. This would exclude the Vantaa lines that are split into two columns around the cables. It would include poles that have guy wires or buttress poles for lateral support. - T99 21:48, 23 April 2011 (BST)
- Which would then make the File:Powerpole-branching01.png, which you mentioned below, a tower, and IMO it sure ain't one - it's just too small. If the criteria was limited only to structures carrying lines with a voltage of 20 kV to 60 kV (or thereabouts), then it might be reasonable. Terrain conditions might have forced some local exceptions, but generally anything designed for sub 20 kV isn't going to have towers (too small), and anything above 60 kV (or 69 kV, as you say) needs a safety distance long enough to make the structures towers.
- I'm open to a wide variety of ideas and suggestions on how to define the pole/tower disctinction universally, unambiguously and objectively, using criteria that can be easily evaluated by most mappers, either on the field or from aerial imagery. (I have searched the web for documents that reveal the exact voltages for specific lines, but maybe that has been too much of a distraction.) By the way, here is another interesting (and not that rare) configuration from a source that cannot be traced from but that hopefully can be discussed. Each of the three phases of a single circuit is carried by a separate guyed wooden pole, not attached to the other poles. How would one evaluate if this is one tower, three towers, one pole or three poles? - T99 09:30, 27 April 2011 (BST)
Looking at File:Powerpole-branching01.png, there are actually two adjacent poles connected to form a single towerlike structure. I have tagged similar structures as a single power=tower node, but this of course is also open to discussion.
I haven't tagged simple transformers. In the rural areas we have "cans" like this, but in cities the transformers are underground or in a power=cable_distribution_cabinet. (I sometimes tag these cabinets with ref numbers just as a proof that I actually surveyed the area in person rather than just copying street names and house numbers from the city's GIS.) Is a node with both pole and substation tags (power=pole;sub_station) rendered correctly?
Should there be a separate tag (e.g. power=transformer) for pole-mounted transformers that are significantly smaller than a regular substation?
- T99 23:31, 23 April 2011 (BST)