Some lines use two power rails, such as the London Underground. This could be made explicit by electrified=dual_rail. Sometimes one rail is grounded and the other rail has a positive voltage; sometimes both rails have (different) voltages. On the London Underground the centre rail is at -210/250V and the outside rail is at +420/500V (see London Undergound). Shall we tag this as voltage=-210;420 (or voltage=-250;500) ? Some (above-ground) parts of the system have the centre rail at 0V and the side rail at the positive supply voltage, to allow track-sharing between London Underground 4-rail trains and normal 3-rail trains.
More information on Wikipedia.
- Kinda surprised after a decade, OpenRailwayMap/Tagging has not handled these. As a historic note, they wrote electrified:rail=* for contact location (as a further side note: could be generalied to guideways). -- Kovposch (talk)
- No, it hasn't. This is talking about details (rail location, contact location, voltage, etc) further to 3rd, 4th, or any other non-overhead conductor rail electrification. Moreover, User:Jimstn has raised concerns in regarding rubber-tyred guideways in Talk:Proposed_features/3rd_and_4th_rail. -- Kovposch (talk) 08:37, 7 July 2020 (UTC)
Distinction between 3-rail and 4-rail
Further to this discussion: I'm a railway electrification engineer in the UK, and a group of us planning to use OSM data to generate an electrification-focused map. I support everything thats been said above - extra tags are needed to differentiate 3rd and 4th rail systems, as well as dual system tracks (overhead contact + 3rd rail or overhead contact + 4th rail).
Terminology is important, and "3rd rail" and "4th rail" are used worldwide to describe these systems. So I would support the following tags: electrified=3rail and electrified=4rail. electrified:rail would continue to be used to define top, side or bottom contact for these systems.
Regarding 4th rail systems where both electrified rails have a non-zero voltage - even London Underground electrification engineers will refer to the system voltage as the voltage between the two rails i.e. 630V not -210V/+420V. So I would recommend to Keep It Simple as voltage=630 and not worry about individual rails wrt earth potential.
- I would like to see overhead conductor rail and trolley wire tagged specifically/separately as well. Currently they are slapped together with catenary wires for pantographs as electrified=contact_line (technically correct in the road sense). I used electrified:contact_line=rail and electrified:contact_line=trolley as a placeholder in the past, so I was going to suggest electrified:rail=*, had you not mentioned multi-system tagging below. -- Kovposch (talk) 17:04, 28 May 2020 (UTC)
- In OpenRailwayMap/Tagging mentioned above, APS is supposed to be tagged as electrified=ground-level_power_supply. They deserve to be organized better. -- Kovposch (talk) 17:32, 28 May 2020 (UTC)
Multiple systems on the same track
On transition sections (and sometimes longer stretches) between overhead and 3/4-rail supply, both types of power are available, each with their own voltage and frequency. How can we tag these sections? --Csmale (talk) 19:57, 8 November 2018 (UTC)
Extending the idea above, a dual voltage section with overhead line + 3rd rail could be tagged electrified=contact_line:3rail, and overhead line + 4th rail would be electrified=contact_line:4rail. That just leaves the question of how to fill out the voltage and frequency keys. For voltage I would suggest the syntax v1:v2, where v1 is the contact line voltage. So 25000:750 for instance. For frequency, a similar syntax e.g. 50:0 for 50Hz AC overhead line and DC 3rd rail. --GazzerK (talk) 16:41, 28 May 2020 (UTC)
- This is not very readable overall, and conflicts with transformer value-pairs non-intutively (as well as 4-rail proposed above Talk:Key:electrified#Additional_stuff). If you really want multi-value under a single key, I might suggest vertical bar "|"-separation (if not the usual colon-delimeted ";" multi-values). Anyway, for crtitical multi-values, multiple tags through suffix is encouraged. While voltage:contact_line=* may appear to be a common syntax, to me properties/attributes such as voltage=* should be suffixed, not prefixed. Somthing as a contact_line:voltage=* would allow additional details for the respective electrification system to be tagged easily. -- Kovposch (talk) 17:17, 28 May 2020 (UTC)
What about electrified wilderness huts?
how to tag those? There are now 30 https://overpass-turbo.eu/s/PNw --PangoSE (talk) 12:08, 16 January 2020 (UTC) https://wiki.openstreetmap.org/wiki/Key:power_supply --PangoSE (talk) 12:17, 16 January 2020 (UTC)