Proposal talk:3rd and 4th rail
Keep electrified=rail for 3rd rail systems
The proposal claims that 4th rail electrification systems are almost only used in the London Underground, plus in Milan.
If this is correct, it seems that very few features will use the new tag, and electrified=rail is enough for most countries in the world. Therefore I would recommend keeping electrified=rail for the common 3rd rail systems, to prevent the need to re-tag so many features and so that current database users (renderers, etc) will mostly keep working. --Jeisenbe (talk) 00:40, 14 June 2020 (UTC)
the proposal has been amended to incorporate your suggestion - thank you. GazzerK (talk) 22:31, 22 June 2020 (UTC)
New value vs sub-tag
I still think it's better to interpret electrified=rail as 3rd or 4th rail, then sub-tag 4th rail under a new key, and assume un-tagged ones as 3rd rail. This would make 4th rail systems remain compataible with legacy tagging. -- Kovposch (talk) 04:11, 15 June 2020 (UTC)
I have changed the proposal so that electrified=rail refers to 3rd rail. This delivers the intent of yor suggestion, without introducing a subtag which would be confusing and error-prone for editors. GazzerK (talk) 22:32, 22 June 2020 (UTC)
I think a subtag would be neater, but have no problem with using 4th_rail to refer to 4th rail electrified systems. The problem is in redefining electrified=rail to specifically mean 3rd rail systems, and the impact on legacy tagging of existing conductor rail systems. I don't think this is restricted to London and Milan: There are dozens of rubber-tyred metro systems (hundreds of km) all over the world which are tagged with electrified=rail. They have either 'two' or 'four' rails depending on what you want to call a rail, but this proposal will result in them all being incorrectly tagged as 'third-rail' systems overnight. See Paris, Singapore, Mexico, Sapporo etc. A subtag would seem to have wider usefulness, as there are trolley-wire systems with one or two conductors, and (less significant) use of dual contact_line systems--Jimstn (talk) 13:25, 26 June 2020 (UTC)
- Oh right, I forgot about this. There are so many different rubber-tyred metro system architecture/design out there. A basic technical understanding of them would be required first. -- Kovposch (talk) 14:51, 26 June 2020 (UTC)
- That being said, I wonder how much should we worry about current return. Aside from comparatively well-known examples of multi-rail systems like Paris Metro, some such as Sapporo Netri's Tozai and Touhou lines, and the Translohr rubber-tyred tram (some Bombardier GLT system uses twin trolley pole) uses overhead line collection + guide rail return. These may commonly be seen as overhead line electrified. -- Kovposch (talk) 15:28, 26 June 2020 (UTC)
Minor wording suggestions
A few things that I would change to make the wording better. YMMV:
- contact_line description: I would not list the different abbreviations, as it seems to be only a selection and there are many of them. I would instead use "overhead line" and link to the Wikipedia article of the same name, where those abbreviations are mentioned. Wikipedia also uses the term overhead line in this article. Instead an explicit mention that overhead conductor rails are considered a contact_line and not a rail could be useful. I have already seen and fixed ways where rail was used and it was obvious that this was still overhead, e.g. a tunnel in Austria with contact_line tracks were used on both ends of the tunnel.
- ground-level_power_supply: the usage of both dash and underscore in the same value will for sure lead to various tagging errors. I suggest using all underscores
- "Used for tracks electrified with ground-level power supply on Wikipedia." What happens to tracks not on Wikipedia? ;) Drop the last 2 words.
- Link "Open Rail Map" at the bottom -> OpenRailwayMap