Proposal:3rd and 4th rail
| 3rd and 4th rail | |
|---|---|
| Proposal status: | Approved (active) |
| Proposed by: | GazzerK |
| Tagging: | electrified=4th_rail |
| Applies to: |  
|
| Definition: | A track electrified with a 4th rail system, with two additional rails on insulators and two shoe pickup by the train, and traction current returning via one of the insulated rails |
| Statistics: |
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| Draft started: | 2020-06-08 |
| RFC start: | 2020-06-09 |
| Vote start: | 2020-06-22 |
| Vote end: | 2020-07-06 |
Proposal
It is proposed that the current railway tag electrified=rail is retained and the definition clarified, to make it clear that it is specifically for 3rd rail systems; and to introduce a new value, electrified=4th_rail. This will allow 3rd and 4th rail electrification systems - which are fundamentally different, in both their mechanical and electrical operation - to be correctly identified and differentiated.
In relation to this, better guidance on the use of electrified=yes is proposed; and also a more accurate definition of electrified=contact_line is proposed.
| The Feature Page for the approved proposal Key:electrified is located at [[1]] |
Rationale
The current electrifed=rail tag is designed to capture railway electrification of the ground level contact rail type. These systems use additional rail(s) which are insulated from earth and carry a voltage. Pick-up shoe(s) on the train collect current from one of the rails. In 3rd rail systems, the current returns to the supply though the ordinary running rail(s). In a 4th rail system, a second insulated rail is provided, and current return is via a second set of pickup shoes through to the second insulated rail. "3rd rail" and "4th rail" are universally-recognised terms for these systems.
The two systems are thus quite different in both their electrical operation, and their mechanical layout. However, both systems are currently tagged electrified=rail, and there is no other way to differentiate these two different systems in OSM.
This is primarily a problem for mainland United Kingdom, where we have a significant amount (400 route km) of 4th rail in operation.
Electrified=rail has been left with the existing value to remove the need for large-scale retagging.
Examples
The vast majority of ground level contact rail systems worldwide are 3rd rail. However, the entire 400 route km of the London Undergound network uses 4th rail, as does the (much smaller) Milan Metro line 1.
Tagging
Proposed tagging is as follows. The whole of the electrified=* tagset is shown for context.
| Key | Value | Property | Description | Default value |
|---|---|---|---|---|
| electrified | yes | Electrified - system not specified | This tag is to be used when the system of electrification is unknown. Mappers should use electrified=contact_line, rail, 4th_rail, or ground-level_power_supply where they are able to identify the system by use of aerial imagery or other means. | |
| no | Not electrified | Used for non-electrified tracks. | ||
| contact_line | Contact line | Used for tracks electrified with Overhead Contact Line (OCL) / Overhead Contact System (OCS) / Overhead Line Equipment (OLE) | ||
| rail | 3rd contact rail | Used for tracks electrified with a 3rd rail system, with one additional rail on insulators, using shoe pickup by the train, and traction return via the running rail(s) | ||
| 4th_rail | 4th contact rail | Used for tracks electrified with a 4th rail system, with two additional rails on insulators and two shoe pickup by the train, and traction current returning via one of the insulated rails | ||
| ground-level_power_supply | ground-level power supply | Used for tracks electrified with ground-level power supply on Wikipedia. |
Applies to
All and part of a way tagged with railway=rail.
Rendering
This proposal provides a handle for renderers to refine rendering based on the type of contact rail in use.
Features/Pages affected
Additions to wiki pages and tables about railways. This proposal does make any changes on to current 3rd rail electrified railways using electrified=rail.
The explanations for electrified=yes and electrified=contact_line do not affect assets using those tags at all - they simply encourage the use of a more definitive value (when it is possible to determine the type of system) and add the industry-standard terminology for contact_line to assist the reader.
External discussions
Discussion of the proposed change with the OpenRailwayMap group.
Comments
Please comment on the discussion page.
Voting
Voting on this proposal has been closed.
It was approved with 23 votes for, 1 vote against and 1 abstention.
I approve this proposal. --EneaSuper (talk) 11:41, 29 June 2020 (UTC)- I approve this proposal. --MichaelDono (talk) 14:11, 24 June 2020 (UTC)
- I approve this proposal. --Csmale (talk) 20:18, 22 June 2020 (UTC)
I oppose this proposal. Proposal from 06.2020 and start voting in same month... give more time for discussions! --Luschi (talk) 20:42, 22 June 2020 (UTC)
- I approve this proposal. -- Sierra 7 (talk) 13:01, 23 June 2020 (UTC)
- I approve this proposal. --Aembleton (talk) 14:07, 23 June 2020 (UTC)
- I approve this proposal. --Emiriku (talk) 16:53, 23 June 2020 (UTC)
- I approve this proposal. --Jeisenbe (talk) 20:49, 23 June 2020 (UTC)
- I approve this proposal. --Pedromorgan (talk) 20:50, 23 June 2020 (UTC)
- I approve this proposal. --Thomas Wood (talk) 22:24, 23 June 2020 (UTC)
- I approve this proposal. --Guidaccia (talk) 22:28, 23 June 2020 (UTC)
- I approve this proposal. --Chuck (talk) 01:42, 24 June 2020 (UTC)
- I approve this proposal. --Seatsea (talk) 08:54, 24 June 2020 (UTC)
- I approve this proposal. --EM311 (talk) 12:27, 24 June 2020 (UTC)
- I approve this proposal. --Mdeen (talk) 15:50, 24 June 2020 (UTC)
- I approve this proposal. --Chris2map (talk) 20:15, 24 June 2020 (UTC)
- I approve this proposal. --Renecha (talk) 20:12, 25 June 2020 (UTC)
- I approve this proposal. --AnakinNN (talk) 21:58, 25 June 2020 (UTC)
- I approve this proposal. Initially, I preferred deprecating electrified=rail and splitting it up into
3rd_railand4th_rail. However this involves lots of unnecessary retagging which convinced me to agree. --Nakaner (talk) 13:07, 26 June 2020 (UTC) 
I have comments but abstain from voting on this proposal. While I personally don't prefer this, I see no need in redefining electrified=rail as this is a proposal on 4th-rail, and any more specific consideration to any other non-overhead above-ground conductor rail electrification system is absent. -- Kovposch (talk) 15:00, 26 June 2020 (UTC)- I approve this proposal. --Dakon (talk) 14:37, 28 June 2020 (UTC)
- I approve this proposal. --AgusQui (talk) 16:37, 28 June 2020 (UTC)
- I approve this proposal. --Riiga (talk) 06:12, 29 June 2020 (UTC)
- I approve this proposal. --Juan Carlos G F (talk) 22:10, 29 June 2020 (UTC)
