Is this Rust?

This isn’t coming off with 3% pretreat, Surface cleaner or wand. Has anyone ever seen this before? It looks like rust but I don’t know why rust would be all over thousands of feet of walkway

Looks like rust.

But 3% won’t kill some organics so after you try 3% with no effect, then try a higher %.

It’s rust, most likely from a snow plow blade


Ah, I hadn’t thought about snow removal machines. That makes sense

Thank you guys