Add highways under construction

[jleedev]

Fixes #212

Treatment is minimalist. Main purpose served is to identify what a gap in the road network might represent, particularly for a long-term road closure. Only attributes included are whether it is trunk/motorway (red) or other roads (blue). Includes the name, in that same color, which additionally contrasts with regular roads.

Omits path, track, and raceway.

Doesn't use the words "under construction"; the dotted line should imply the noncorporeal nature of the feature, and the color (and the geometry these features tend to have) should clue the viewer that this is related to the highways.

Includes the name property only. While some roads under construction might only have a ref and some route relations, it generally looks weird to have shields floating above roads that aren't there yet, and it looks perfectly fine for a highway under construction to not have any label.

Layer count: 2.
Avoids attempting to render "the entire road style, but dashed", as that proved to be impracticable in #215, in taming the style, the number of layers, and visually. Ignoring bridge/tunnel is probably the right choice.

This should be sufficiently distinct from railways, unpaved roads, and admin_8 borders, but maybe not.

[ZeLonewolf]

Surprisingly workable based on the screen shots.

[jleedev]

Ah, meant to include some over water:

[ZeLonewolf]

So the main issue with the prior approach was with dual carriageways merging dash patterns at lower zooms. Do these look okay at the lowest zoom they appear?

[adamfranco]

This looks reasonable to me. The color makes it distinguishable from future (likely brown) track rendering.

[jleedev]

Slightly chunky at z12:

Slightly mushy at z11.9 (deliberate as these are on their way out the door):

This is somewhat unavoidable when using dashes, in part due to them jumping at integer zoom levels. But I think it looks ok, and they quickly calm down by z12.5. Kind of look like bricks, if that's what freeways were made of.

[ZeLonewolf]

Yeah that seems again surprisingly workable. Like to get a review from @1ec5 as the author of the previous attempt but otherwise looks good to me.

[1ec5]

Thanks for taking a fresh look at this issue. This approach seems intuitive enough and avoids piling onto the layer situation (which is actually the main thing that caused #215 to stall in my opinion). Even a major freeway under construction doesn’t need to be in the user’s face, so long as it fills a gap.

[1ec5]

Good idea to make everything thin, including the dashes. That neatly gets around the issues with overlapping, mismatched dashes that I had run into in #215. However, the dashing can be a very subtle effect at some zoom levels. In the screenshot below, the U-shaped road is also under construction:

Can we widen the gaps a bit at the lower zoom levels to keep the roads from looking like a different classification of corporeal road? It seems to be more of an issue with non-motorways; the blue somehow contrasts less well with the land background color and other roads.

We should also double-check the output on 1× displays.

[jleedev]

Changed line-width to 1, always, causes the dashes and gaps to be uniform across both stylings:

[1ec5]

I’d still be interested in revisiting the label glosses from #215 at some point. Without a legend that’s in the user’s face, any relatively rare line treatment will be subject to misinterpretation. This also goes for busways (#308), for example. But we can tackle that in a separate issue. The differently colored labels already do a great job of signaling to the user that there’s something altogether different about these roads.

[jleedev]

Doesn't read well at low resolution, scaled up ever so slightly.

Before:

After:

[1ec5]

My taxpayer dollars at work!