Calling Casper Runners and Art Lovers - Can You Tell Us What This Is?

I was walking along the Platte River Trails trying to get some outdoor exercise before the summer was over. That's when I noticed some strange graffiti or sign on one of the underpass pillars. But then I noticed another, and then another. Of course I started to get curious, what was the purpose behind this artwork? Or is it simply graffiti?

Maybe I'm overthinking this a bit, but at first I thought this was an area for runners to purge their system during a run. But only because it looked like a pretty good place to try and alleviate the nauseous effects of strenuous exercise. As a former long distance runner, I'd never seen anything like this before.