Those yellow bump things for blind people. They need to follow a spec that then in turn cart manufacturers, wheelchair manufacturers, and wagon cart manufacturers all build around so that when I travel over them they don’t jostle my whole cart around and tip over my drink.
If you’re from the west coast of the US that seems to be a more West Coast thing. I recently went to Chicago and was amazed at how clean it was. The Lyft driver told me it was the cleanest city in the country (and possibly the world since he grew up outside of the states) but I wasn’t prepared for it. I walked everywhere in the city and there just wasn’t a single piece of trash anywhere. We actively looked too.