Support multiple train protection systems on the same line

[hiddewie]

Originally posted by @hiddewie in #496 (comment)

Some tracks have multiple train protection systems active at the same time.

Given that train protection systems under construction are rendered as a dashed line, we might have to find an alternative way to render multiple train protection systems. Or if it is infeasible, close the issue.

[MatisseBE]

Could having the ability to create a legend with customisable logic be considered as a (partial) solution to this issue?
The UI/UX is probably a hard one to crack, but maybe someone finds a way.
#416

Alternatively, we could keep the prioritisation method on zoom-outs, and switch to predefined national colour combinations at smaller zoom levels. This could be an issue if multiple countries are in view though.

Other options at smaller zoom levels:
(1. Predefined national colour combinations)
2. Reduce the opacity of each colour and let them mix dynamically (ie not a predefined color set) to create new unique colours. This might result in a lot of smudgy colours, though. And the link with the original colours/TPS might not be obvious either.
3. Perhaps that could be mediated by creating a gradual/faded mix, where the outsides of the lines are the original colour and closer to the middle they become more mixed. Downside is that it's impractical with 3 or more systems at once.
4. Intertwined 'lines' are an option but it might be too easy to be falsely interpreted as a separate tracks. I do think this could be a worthy solution.
5. Increase line width (and bundle nearby tracks at relatively larger zoom outs) and show colours in parallel.

Just throwing some ideas out there, maybe it helps someone with their own brainstorming.

[RemiCardona]

Been thinking about this for a while, there are plenty of use cases:

• different electrification modes : eg 3rd rail + OHLE on some lines in/near London 🇬🇧, Penn Station in NYC 🇺🇸
• switchable electrification systems : 15kV + 25kV near Genève - La Praille 🇨🇭
• ETCS L1/L2 + PZB/KVB/ASFA/… in 🇪🇺 , various PTC systems in the NE Corridor 🇺🇸

Overall, I think something can be worked out using dashed lines like in the O.G. ORM. I think up to 3 variants at high-zoom levels can be shown. At lower levels, a "prominent" system may be picked (e.g. ETCS over national type B systems).

(ORM.app is giving me 512 error codes, I can't check if this was ported over to the vector map)

[MatisseBE]

Getting the 512 as well.

[hiddewie]

The errors are caused by #574 changing the port from 443 to 8443. I missed that breaks the public domain as well, only port 443 can be used for Cloudflare. I will fix that so the errors disappear.

--> #584

[hiddewie]

Thanks for the input so far on this issue.

Could having the ability to create a legend with customisable logic be considered as a (partial) solution to this issue?

This would be great, but so far attempts at making the map style more dynamic are met with recurring limitations in the Maplibre GL JS library. We may get this working, but it takes time.

2. Reduce the opacity of each colour and let them mix dynamically (ie not a predefined color set) to create new unique colours. This might result in a lot of smudgy colours, though. And the link with the original colours/TPS might not be obvious either.

Mixing colors together is not clear I think. The same base color could generate multiple different other colors on the map mixed with other colors.

5. Increase line width (and bundle nearby tracks at relatively larger zoom outs) and show colours in parallel.

This could work 👍

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I am considering showing multiple train protection systems using dashes like suggested. The base color could be the international train protection, and added on top are the dashes of the more country-specific train protection systems. The ordering can follow from the ordering in the YAML configuration, just like now.

Then, for lines which have train protection under construction we need a different solution, because that currently uses dashes to show the train protection system under construction. I think we could make an outline of the railway line with dashes, "around" the current railway line.