I like the idea of a cement insert in the cone that someone is going to run over in their car because they are going to ignore the cone.
Inconveniently sized brush across the sidewalk seems like the necessary blockage for some people. Yesterday and today we were removing the largest dead ash, I've seen (I haven't seen many ashes, mostly oregon ash here that doesn't get so big). Three cones across the sidewalk with a Danger Area Do Not Enter sign hung on the middle cone. Bucket truck, dump truck, chip truck, chipper, and tractor in the work area. Didn't stop a stupid woman from walking right in. I kept yelling HEY at her until she couldn't ignore me any longer, then just looked over sheepishly. STUPED, Dum peeple. I thought of this thread, and knew I wasn't alone.