Business and local governments are installing these Tactile Warning Devices everywhere to assist blind people. I was entering a bike trail and had to ride over one of these and had my bike slip out from under me. It was like hitting ice. Hard as rock plastic with no grip. Hurt my wrist, shoulder and ruined a nice helmet. Anyone else feel the wrath of these ridiculous things? Seems that by improving safety for one group the government is creating a hazard for the rest of us. I was not going very fast when my my bike slipped out from under me.