add Dresden tram signals

[jonaes]

Hello,
there are some Dresden-specific tram signals that would be great to have rendered.
I tried to add it to the yaml file myself, but I couldn't really figure it out.

New signals:

The tags are documented here: https://wiki.openstreetmap.org/wiki/DE:OpenRailwayMap/Tagging_Trams_in_Germany#Dresden

I uploaded svg files for the signals here: https://gist.github.com/jonaes/d46237c69339bc35e23db214d5f225a6

G3a

• The end of a speed restriction, that was higher than the default speed of 50 km/h. For the foreseeable future, there is only the 60 km/h variant.
• Tagging similar to the G3 signal:

railway:signal:speed_limit=DE-DVB:g3a
railway:signal:speed_limit:form=sign
railway:signal:speed_limit:speed=none

G5

• Start of a speed restriction, which is only valid for the next situation (eg. switches, bridge, crossing, etc.)
• Tagging similar to the G2 signal:

railway:signal:speed_limit=DE-DVB:g5
railway:signal:speed_limit:form=sign
railway:signal:speed_limit:speed=10/20/30/40/50

So11

• curve lubrication system ahead
• Tagging:

railway:signal:minor=DE-DVB:so11
railway:signal:minor:form=sign

So5a

• basically a standard-BOStrab So5 (no passing) but with the additional information, that oncoming trams have priority.
• could be added either separately or as a variant of So5
• Tagging:

railway:signal:passing=DE-DVB:so5a
railway:signal:passing:type=no_passing_give_way
railway:signal:passing:form=sign

So25

• basically the lower part of a BOStrab:bü signal attached to a normal BOStrab:f signal, indicating that the crossing may be passed if the signal is not working if traffic is allowing.
• should ideally be displayed below (different combinations of) BOStrab:f signals
• Tagging:

railway:signal:crossing=DE-DVB:so25
railway:signal:crossing:form=sign 

So 13/14

• priority over / give priority to other traffic
• so those signals are the same as the already existing So11 and So12 from Rostock (RSAG). This raises the question of how to handle such a situation, especially as there are more German cities using those signals, probably all using different names for them.
• I didn't include svg files for those signals, because they would be the same as the RSAG ones.
• Tagging:

railway:signal:minor=DE-DVB:so13
railway:signal:minor:form=sign
railway:signal:minor:type=give_way

railway:signal:minor=DE-DVB:so14
railway:signal:minor:form=sign
railway:signal:minor:type=has_priority 

Fahrsignale not rendering as expected

Aditionally, there are some normal BOStrab-Fahrsignale in unusual combinations (because the DVB loves to create new combinations), which don't render as expected:

combined departure signals

example: https://www.openstreetmap.org/node/12763035719

expected: three lights showing pt_requested, close doors (a1), depart (a2)

( A )
( T )
( O )

no F0 aspect

There are several combinations which can't show a F0 aspect (the whole signal is just dark when not showing something else). They all render with the F0-signal head
Examples:

• priority requested, f4, f1: https://www.openstreetmap.org/node/9288948843
• priority requested, f1: https://www.openstreetmap.org/node/13015719191
• f1 only: https://www.openstreetmap.org/node/13015719198

Thanks for looking into this!

[entbert]

The new G and So signs are not a problem. I can implement those. (Thanks for the SVGs!)

Regarding So 13/14, it works either way, but I think it might be worth it to unify the tagging, see my comments on the wiki talk page.

Simply adding the So 25 under Fahrsignale makes the already large icons too large, I think. In particular at intersections, the main part of the signal is placed far from the track it belongs to and might be associated with a different track:

What do you think about a smaller icon like this?

(By the way, I think from your description of the So 25 that it might be better tagged as a traversable type signal rather than a crossing one.)

For the departure signal, rendering both the A 1 and A 2 state is not a problem.

But adding the request "A" signal to departure signals would in our current logic mean that at a Fahrsignal with an integrated departure signal (example), two "A" would be rendered. I am not sure about that.

I don't understand what you mean regarding the F 0 signal. Do you mean the empty light?

[jonaes]

Thanks for your comments!

• So13/14: I answered on the wiki page :) Let's see if anyone else has an opinion there
• So25: I agree that the icon gets too large if added below. However, I don't really like the rectangular version. Idk, but for me it doesn't catch the look and feel of "real" version at all. Maybe it would be possible to add the sign to the side of the Fahrsignal, as with the signals in the screenshot here: CZ signalling (part 2) #822 (comment)?
  You might be right with tagging it as traversable. I thought of it basically as the lower part of the Bü signal cut off and attached on a Fahrsignal in order to Bü-ify it, hence the classification as crossing:...
  (You might notice I only just started working with the tagging beyond the JOSM presets 😅)
  I'll have a closer look into that tomorrow.
• For the departure signal: I understand the problem. Would be fine by me to leave it like that for now.
• F0: Yes, I mean the empty light. I don't know what the intended meaning of it is, but I always interpret it as "there's the possibility to display an F0 aspect", which isn't true for the occurences I mentioned. (Example on StreetView

[entbert]

Regarding the Fahrsignal, I have also been wondering why the F 0 state is not rendered. (Maybe to avoid showing "impossible" states with both F 0 and F 1 at the same time? But the other aspects which we do render usually do also not occur at the same time.)

In #834 I have now suggested to render every aspect exactly as tagged.
This also fixes your problem with the departure signal (except for the request "A").

The Dresden-specific signals will follow.

[entbert]

Regarding So 25:

• Rendering it to the right of the signal is possible. (Size and margin could of course be adjusted.)

• But: This only works by rendering the So 25 as part of the main signal. This leads to the question marks above the signals, as the map knows that a crossing signal has been tagged, but none is rendered. I know of no way to change this (except for some hacky solution like an empty icon).
• It could be solved by changing the type to traversable, (I assume) because this is not a type of signal defined here. Though I don't know if it was intentionally left out there or might be added later, @hiddewie?
• Another solution on the tagging side would be to not tag the So 25 as its own signal, but interpret the Fahrsignal in its presence as a new type of signal like railway:signal:crossing = DE-DVB:f, railway:signal:crossing:states = DE-DVB:f0,…. This is similar to the Karlsruhe (EBO) signal Bü 200/201 which is also just a Fahrsignal with an additional plate (example).
• To be honest, I like the previous version with the square icon better anyway. If you like, I could also make it a bit higher so that it gets one stripe more.

[entbert]

Apart from So 25, I have now finished all of the Dresden signals.

I have mostly made only slight adjustments to the symbols (adjust size of So 5a to that of So 5; lighten the blue border of G 5 to make it distinguishable from G 4 even at the size of single pixels).

But for So 11 I made a larger change to the look of the signal as I found the original one to be too busy. (Yours on the left, my suggestion on the right.)

As you already didn't like my simplification for the So 25, I wanted to ask if this is okay with you.

[hiddewie]

It could be solved by changing the type to traversable, (I assume) because this is not a type of signal defined here. Though I don't know if it was intentionally left out there or might be added later,

The traversable tags are usually attributes of a signal, and not a signal "type" by itself. Concretely at the moment there are no signals implemented in the OpenRailwayMap with only the railway:signal:traversable tag used to determine that signal, and no other tags. If we want to implement icons just using the railway:signal:traversable tag, we can add it to the list, no problem!

[entbert]

If we want to implement icons just using the railway:signal:traversable tag, we can add it to the list, no problem!

But then a question mark would again be rendered at signals where the traversable is rendered as part of a main signal, would it not? Then it would not make sense to change the signal category here.¹ Is there a different way to suppress the question mark when a "top-level" signal like railway:signal:crossing (or maybe railway:signal:traversable in the future) is rendered only as an aspect of another signal?

Footnotes

1. display-wise – I still think traversable would fit better to its funtion. ↩

[hiddewie]

How the signal feature matching works is:

• Every feature in the database is matches against the tags in the tags section of the features list. The first feature that matches "wins" and is determined to be the matched feature.
• The used signal categories to match a feature are taken into account. So for example when the tags section lists both railway:signal:main = ... and railway:signal:crossing = ..., then both categories are considered matched, and further matching for those two categories will not happen.
• For a matched feature, the section icons is used to determine one or more (stacked) icons to actually display the feature on the map. Within the icons section there can be multiple icons which can match tags. These tags and the category of the tags are not taken into account for determining the signal categories like those in the tags section.

So basically to suppress the question marks is to match the single feature against multiple tag categories. An example is

OpenRailwayMap-vector/features/signals_railway_signals.yaml

Lines 6469 to 6477 in f0e0f20

	- description: train protection block marker light
	country: NL
	icon: [ default: 'nl/main_light_white_bar' ]
	tags:
	- { tag: 'railway:signal:main', value: 'NL' }
	- { tag: 'railway:signal:main:form', value: 'light' }
	- { tag: 'railway:signal:train_protection', value: 'NL:228' }
	- { tag: 'railway:signal:train_protection:form', value: 'light' }
	- { tag: 'railway:signal:train_protection:type', value: 'block_marker' }

where a single signal matches both the railway:signal:main and railway:signal:train_protection tags, so no further features for main and train_protection categories will be matched, and no question mark for the train_protection unknown signal will be shown.

[entbert]

So we have to introduce two copies of the Fahrsignal feature, with and without the So 25 present?

- description: tram Fahrsignal with So 25
    country: DE
    exampleIcon: de/bostrab/f1-old
    icon:
      - match: 'railway:signal:main:PT_priority'
        cases:
          - { exact: 'requested;off', value: 'de/bostrab/st9' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { any: [ 'DE-AVG:f0', 'DE-BOStrab:f0' ], value: 'de/bostrab/f0', description: 'F 0' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { any: [ 'DE-AVG:f4', 'DE-BOStrab:f4' ], value: 'de/bostrab/f4', description: 'F 4' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { any: [ 'DE-AVG:f1', 'DE-BOStrab:f1' ], value: 'de/bostrab/f1', description: 'F 1' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { any: [ 'DE-AVG:f2', 'DE-BOStrab:f2' ], value: 'de/bostrab/f2', description: 'F 2' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { any: [ 'DE-AVG:f3', 'DE-BOStrab:f3' ], value: 'de/bostrab/f3', description: 'F 3' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { any: [ 'DE-AVG:f5', 'DE-BOStrab:f5' ], value: 'de/bostrab/f5', description: 'F 5' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { exact: '?', value: 'de/bostrab/fahrsignal-empty', description: 'further, unidentified aspects' }
        position: bottom

      - match: 'railway:signal:crossing'
        cases:
          - { exact: 'DE-DVB:so25', value: 'de/dvb/so25', description: 'So 25' }
        position: center

    tags:
      - { tag: 'railway:signal:main', any: [ 'DE-AVG:f', 'DE-BOStrab:f' ] }
      - { tag: 'railway:signal:main:form', value: 'light' }
      - { tag: 'railway:signal:main:states', any: [ 'DE-BOStrab:f0', 'DE-BOStrab:f1', 'DE-BOStrab:f2', 'DE-BOStrab:f3', 'DE-BOStrab:f4', 'DE-BOStrab:f5', 'DE-AVG:f0', 'DE-AVG:f1', 'DE-AVG:f2', 'DE-AVG:f3', 'DE-AVG:f4', 'DE-AVG:f5' ] }
      - { tag: 'railway:signal:crossing', value:  'DE-DVB:so25' }
      - { tag: 'railway:signal:crossing:form', value: 'sign' }


- description: tram Fahrsignal
    country: DE
    exampleIcon: de/bostrab/f1-old
    icon:
      - match: 'railway:signal:main:PT_priority'
        cases:
          - { exact: 'requested;off', value: 'de/bostrab/st9' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { any: [ 'DE-AVG:f0', 'DE-BOStrab:f0' ], value: 'de/bostrab/f0', description: 'F 0' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { any: [ 'DE-AVG:f4', 'DE-BOStrab:f4' ], value: 'de/bostrab/f4', description: 'F 4' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { any: [ 'DE-AVG:f1', 'DE-BOStrab:f1' ], value: 'de/bostrab/f1', description: 'F 1' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { any: [ 'DE-AVG:f2', 'DE-BOStrab:f2' ], value: 'de/bostrab/f2', description: 'F 2' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { any: [ 'DE-AVG:f3', 'DE-BOStrab:f3' ], value: 'de/bostrab/f3', description: 'F 3' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { any: [ 'DE-AVG:f5', 'DE-BOStrab:f5' ], value: 'de/bostrab/f5', description: 'F 5' }
        position: bottom

      - match: 'railway:signal:main:states'
        cases:
          - { exact: '?', value: 'de/bostrab/fahrsignal-empty', description: 'further, unidentified aspects' }
        position: bottom

    tags:
      - { tag: 'railway:signal:main', any: [ 'DE-AVG:f', 'DE-BOStrab:f' ] }
      - { tag: 'railway:signal:main:form', value: 'light' }
      - { tag: 'railway:signal:main:states', any: [ 'DE-BOStrab:f0', 'DE-BOStrab:f1', 'DE-BOStrab:f2', 'DE-BOStrab:f3', 'DE-BOStrab:f4', 'DE-BOStrab:f5', 'DE-AVG:f0', 'DE-AVG:f1', 'DE-AVG:f2', 'DE-AVG:f3', 'DE-AVG:f4', 'DE-AVG:f5' ] }

[entbert]

An unrelated point I noticed when testing is that stacking icons with position: center leaves too large of a margin to other icons and the caption.

(Two different versions of the So 25 icon used here. The borders of each are marked in pink here for clarity.)
position: center

position: right