render shared paths differently

[k-yle]

Closes #10139

Currently, it's impossible to tell the difference between the Cycleway and Cycle + Foot Path presets.

There are 6 special countries that use a different preset, which is simiarly confusing, since it renders exactly the same as crossing=*.

This PR makes the styling consistent for bicycle=designated + foot=designated, regardless of whether you use highway=path or highway=cycleway

Before
After	(only the bottom 2 have changed)

[tordans]

@k-yle thanks for kicking this off! I am wondering, if we can find a system in how we use the background vs. dashed line.

• Background for highway class
• Dashed line for modifiers and access
• pathy things are brown
• foot stuff is white
• bicycle stuff is blue

My mental model has a hierarchy like this on this topic:

We could translate this in something like:

Document: https://docs.google.com/presentation/d/1zQ6mqbGgyRRwq9Zakof_kPfAzX1JeRVplxMr4SLKMsQ/edit?usp=sharing

Notes:

• hw=cycleway + foot is used a million times
• hw=cycleway should probably also trigger on foot=yes because any non-cycle traffic is the modifier
• the background colors need to be slightly different when modifiers are applied to make them look the same (the colors interact which makes them look different)
• The new blue for cycleways would give a nudge to the rendering on osm carto which I think is a plus
• on footway=sidewalk: I wonder if we should also change the dash style a bit and not just the color. the color change is super subtle. hw=stairs has a smaller dash, maybe something in between? (but I cannot simulate that in powerpoint :-D) – however: see below on crossings

[tordans]

And for the crossings…

Note: In openstreetmap/id-tagging-schema#1201 (comment) I added crossing presets to match all the main way presets.

Given that both background and dash color are now reserved what else can we change?

• Change the dash style (shorter, longer)
• Add a solid border like on highway hw=service+service=alley
• Add a dashed border like on hw=path
• Modify the background color to something darker/lighter

Thoughts:

• A different dash style is probably the easiest. We use it for hw=strairs but those are green dashes and distinct. It kind of indicates "slow down", which is OK for a crossing.
• Dashed borders collide with the markings presets; it could look like they are a markings-visualization
• Solid borders would work. They could collide with other service styles but should never directly connect so no real issue here. However they kind of signal a higher class of road or signal safety which does not fit for a crossing.
• Modified backgrounds is hard when we use white for footways. We could try something like a "neutral dark gray" for the white, a "warm dark gray" for the path and a "blue dark gray" for the bicycle ways.

[k-yle]

Sorry for the delayed reply, this comment suprised me:

My mental model has a hierarchy like this on this topic:
image

because I thought that (highway=cycleway + foot=designated + cycleway=designated) was exactly the same as (highway=path + foot=designated + cycleway=designated). Is there a wiki page which explains the difference? I can't contribute much to this discussion since my understanding of this situation seems to be flawed

[tordans]

My mental model has a hierarchy like this on this topic:
image

because I thought that (highway=cycleway + foot=designated + cycleway=designated) was exactly the same as (highway=path + foot=designated + cycleway=designated). Is there a wiki page which explains the difference? I can't contribute much to this discussion since my understanding of this situation seems to be flawed

You are right. Illustrating stuff is always hard and I mixed two things which did not work…

Looking at it some more, I think the main issue is: You are introducing the new pink color for foot+bike traffic ways.
But hw=path is also foot+bike traffic, just not explicitly.

Does this make sense: The miss-match of Column D vs. I?

Here is the doc…

I don't have a solution ATM.

I really like to separate the crossing styles. But maybe we should look more at options from #10256 (comment) – when we introduce a new modifier to the style, we make it easier to work with what we have for the rest.

I am not sure yet how to handle the access. vs. highway class in the styles.
The main issue is IMO, that hw=path is open for bike+foot traffic by default. And that usually we show the highway class in our style, not the access.

Have to stop now, but 🤔 …

Docs

• https://wiki.openstreetmap.org/wiki/Tag:highway%3Dpath

---

Updated: I added an "Another try" Column.

• The two Cycle & Foot Path presets use the same background as path, because all three are open for bike+foot
• But that system breaks again with 740k footway+bicycle in line 12
• So this 🤔…

[k-yle]

Change the dash style

I think this might be a step backwards from the current situation, where the colours make it easy to distinguish most presets, so I haven't considered it below

Add a solid border
Add a dashed border

These two are already used to distinguish paved/unpaved, so we can't really change the line casing

Modify the background color

I think this is the only option...

The main issue is IMO, that hw=path is open for bike+foot traffic by default.

I overlooked that until now... maybe we need a separate category for unspecified access?

Here's what this could look like, using a modified version of your first diagram, including some of the changes from this table:

(upper line = normal, lower line = crossing)

• this assumes 4 colours for the 4 categories
  • explicit foot = ${\color{#938888} \blacksquare}$ brown
  • explicit both = ${\color{#a267ea} \blacksquare}$ purple (DE:240 / AU:R8-2)
  • explicit cycle = ${\color{#a3c9f2} \blacksquare}$ blue
  • implicit access = ${\color{#ddd8c5} \blacksquare}$ beige
• crossings could use the same colours, but the foregound/background is inverted
• I don't know how to handle the 2 situations in ${\color{#e29999} \blacksquare}$ red. Do people use these tags to indicate that one mode has more priority?