Proposal talk:Platform exits

Problems

Please at least concentrate them in a page eg Key:*:carriages , if not a proposal. It's difficult to understand and discuss.

• destination:*=* : This is for where it leads to, not the exit name. There can be many locations listed on signage.
  • https://www.tokyometro.jp/station/line_tozai/position.html https://www.tokyometro.jp/station/line_images/figure_platform_t11.png In this example, exit name or code is not used at all, only a location. There are many exits and sub-exits for that location. The elevators are shown to be for a certain concourse or gateline.
• destination:ref:*=* : This is for the ref=* of the road, not exit. Compare junction:ref=* at the exit. So it can be the interpreted as the ref=* of the line you can interchange with.
• exit:*=* : It's exit=staircase not exit=stairs , and there is lift . Arguably entrance=staircase etc are bad for the orthogonality with what it leads to. Also this is not about the station exits themselves, but the platform egress.
• *:carriages=* : While this won't be mixed with *:lanes=* as traffic_signals:turn=* would, it's best to avoid reusing vertical bar unless there are good reasons. Eg connectivity=* also use commas differently than how you have used semicolon here. You can see how destination:symbol=* corresponds with the destination=* with semicolon.

—— Kovposch (talk) 16:11, 11 February 2024 (UTC)

Solutions:

• *:carriages=* → Are you aware of FR:Tag:railway=platform_marker and FR:Tag:railway=platform_section ? If you already know the train length, it's easier to parse than inventing another subformat again. You have to draw the railway=platform eventually anyway. Though they are best renamed, and discuss car vs door.
• destination:*=* + destination:ref=* → destination:subway_entrance:name=* + destination:subway_entrance:ref=*
• exit:*=* →
  • destination:steps:*=* : ~1.3k entrance:steps=* likely related to entrance=* to improve it. stairs=* is used differently, and perhaps best not to be mixed in indoor=* together.
  • destination:escalator:*=* : escalator=* is only "deprecated" in favor of conveying=* on the escalator itself, not as attribute on another feature.
  • destination:elevator:*=* : elevator=*

—— Kovposch (talk) 16:30, 11 February 2024 (UTC)

Hi, thanks for your comments.

• Changing destination:ref:*=* to destination:subway_entrance:ref=* seems straightforward. Are you saying that there might be other variants like destination:route:ref=*?
• I've seen railway=platform_marker, but some metro systems don't have these signs. Surveying the exact position where the train stops would be impossible underground. That's why I've been mapping this data using carriages, because carriages are easy to count, and it's exactly the infomation that people need in these systems that don't use railway=platform_marker.
• I don't quite understand what you're suggesting with destination:steps:*=*, do you want to split exit:carriages=* into 3 separate tags? If yes, what would the tag values look like?
• Regarding the | character, I have been using this so that the syntax is identical to destination:lanes=*. So any parser that understands destination:*:lanes=* can be adapted to support destination:*:carriages=*.
• Changing stairs to staircase is simple, originally I saw the tag stairs=* and assumed that was more logical than the other tag steps. Happy to change it, likewise for lift -> elevator if you think that's better?

--Kylenz 08:00, 12 February 2024 (UTC)

I tried using railway=platform_marker at two big stations near me. Conclusion: processing railway=platform_marker is incredibly complicated and error-prone compared to an explicit tag like exit:carriages=*. The rough steps are:

1. Find the stop_position node
2. Find the stop_area relation it belongs to
3. Search the stop_area for the platform_edge with a ref=* that equals local_ref=* from the stop_position node
4. Get all nodes from the platform_edge line to calculate the length of the platform
5. Get all nodes with railway=platform_marker from the platform_edge line, find the most appropriate one (guesswork)
6. Do some more guesswork to match the direction of the track to the direction=* on the platform_marker node
7. Then follow all footways connected to the platform_edge until we find the first feature which has a different level=* tag (e.g. stairs or an elevator), or the first barrier=entrance tag.
8. Calculate the distances between the exits and the most appropriate platform_marker. Split the distances into parallel and perpendicular vectors (fails if the platform is curved)
9. Convert metres into carriage lengths using some external source…

I hope that explains why using railway=platform_marker is a very complex and brittle process. It's also equally complex to map, and basically impossible underground... So I still think an explicit tag like exit:carriages=* is better than trying to guess this data from railway=platform_marker.

--Kylenz 12:50, 9 March 2024 (UTC)

I don't understand how you arrived at this...
3—6. railway=platform_marker should have a platform_edge:ref=* that's simulatenosuly the same as the public_transport=stop_position local_ref=*
7—8. What I meant is you add the destination:*=* on the railway=platform_marker , ie splitting destination:*:carriages=* to each car directly. I was also worried destination:carriages=* may exceed 255char length limit if there are many cars with many different long exit names. At the same time, "Street" should not be abbreviated as "St".
9. This is not needed if the railway=platform_marker ref=* is the same as car number?
—— Kovposch (talk) 09:33, 12 March 2024 (UTC)

Egress vs ingress

• You only considered egress. There was a question about descriptive "names" on platform stairs and escalators. I thought destination=* can be used to solve them, for station navigation signs in general, rather than train access. This would result in destination:*=* being used for 2 directions, distinguished by feature only.
• While you describe this for metro, other trains may be coupled regularly. Then destination:carriages=* is ambiguous, including with to:carriages=* if that is to be used.

—— Kovposch (talk) 01:52, 12 February 2024 (UTC)

Hi, I haven't tried mapping destinations into a station. I don't expect this tagging system to be flexible enough for that... --Kylenz 08:00, 12 February 2024 (UTC)