Explain red octagons

[joeytalbot]

Hi, I was wondering what the red octagons represent on abstreet? Some junctions feature several of them, some have just one. Are they traffic lights?

[dabreegster]

They're stop signs. The rules for assigning them are very simple -- if a larger road intersects a smaller, assume the smaller stops. Size is based on the OSM highway tag: https://github.com/dabreegster/abstreet/blob/ff598f21a39856f5987ccdce8560717d87a56272/map_model/src/osm.rs#L42

So here, the east/west arterial has priority over the south local road:

If you click an intersection and choose to edit, you can change the stop signs. You're allowed to remove all stop signs from an intersection -- Seattle has many places like this. Vehicles still yield; a stop sign just means they come to a complete stop for 0.5s before trying to go.

I'm sure you've noticed spots like:

Now that separate cyclepaths are included, I need to figure out how to merge the two "intersections" into one, which will also reduce the number of stop signs placed.

I'm curious if a different style would make the stop signs more apparent. They're so small -- do you think trying to draw the word STOP is worthwhile?

[Zireael07]

Maybe draw the STOP word if zoomed in enough, and a white squiggle/line otherwise?

[Robinlovelace]

Is this documented @dabreegster? We could have a go at documenting it if that would be useful. I think it could be more clear what they mean!

[joeytalbot]

Thanks for the explanation @dabreegster . Stop signs was my first thought due to the appearance, but compared to the actual physical signs there are far more of these than there would be stop signs. If they are added at each intersection that makes sense.

[dabreegster]

Maybe draw the STOP word if zoomed in enough, and a white squiggle/line otherwise?

I like this idea! It's now possible for us to render the text with vectors so that it'll show up reasonably. Will try this out later.

Is this documented @dabreegster? We could have a go at documenting it if that would be useful.

I think this is a more general project, filed #455

If they are added at each intersection that makes sense.

Here's another example where the placement should match reality a little better.