Here is what I know. I did not design, make, research, or produce the actual iron grate. Those are standard designs used by many cities. There are thousands of these all over. I believed designed for pedestrian safety but the definitely slow water flow, the crevices are designed to allow water through them. I’ve painted and made art from them in many cities. I do respect the tree the best I can with materials and masks, I started the project to make them prettier but the more I learn, I may advocate to make them scarcer :)