Found this while wandering around the Lemon Heights area a few weeks ago, looking for scenic viewpoints. It’s on the Skyline trail, near Peters Canyon park.

It seems to be saying this:

• Cyclists* yield to pedestrians and horses.
• Pedestrians yield to horses.
• Horses yield to no one.

But if you’ve never seen it before, the meaning isn’t clear at a glance.

Apparently the idea is to make everyone stop and try to work out the diagram, so that they can start moving again in the right order.

*Or perhaps only bicycles, since there’s no rider in the picture.