Add rendering for highway=busway

[kolgza]

This is basically the same pull request as #4382, except from a different branch. In other words, I don't know how to use git. @imagico: please request the same changes as before.

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Fixes # (id of the issue to be closed)

• Add rendering for highway=busway. #4226

Changes proposed in this pull request:

The rendering for higway=bus_guideway would be applied to instances of highway=busway.

Test rendering with links to the example places:

• https://www.openstreetmap.org/relation/4051402#map=15/40.4294/-80.0636

Before

After

[imagico]

See comments on #4382.

I am not opposed to the idea of rendering bus only roads built and used for specific bus routes in a distinct fashion. But i don't think the tag highway=busway has shown clear enough adoption and consistency in use by mappers to support rendering it here and i don't think the suggested rendering (in particular the blue color) is a good choice for that - in particular also where these roads connect to the general road network. That is different for bus_guideway - which is more rail like and does not transit to regular roads.

[kolgza]

i don't think the suggested rendering (in particular the blue color) is a good choice for that

This relates to #3396

[kolgza]

That is different for bus_guideway - which […] does not transition to regular roads.

Here is a counterexample:

This issue is inherent to the fact that highway=bus_guideway is rendered like a railway, but must somehow merge into roads.
@pnorman discussed both redoing the rendering for bus guideways, and unifying it with highway=busway.

[imagico]

Also keep in mind #3581 - the rendering of highway=bus_guideway currently suffers from various issues related to layering relative to other roads features. It would not be advisable to extend this highly suboptimal rendering to additional features without addressing those issues first.

[kolgza]

Closing, because I lack the expertise to implement this.