That's a great observation! Yes, those waste bins with the little sand trays on top are specifically designed for smokers, and they are actually quite useful. Their primary function is safety. The sand provides a non-combustible material for smokers to extinguish their cigarettes completely before disposing of the filter tip in the adjacent opening. This significantly reduces the risk of a fire starting inside the bin from a still-smoldering cigarette.
Beyond fire prevention, these bins serve an important civic purpose. They help contain cigarette litter. By offering a designated and convenient place to put out and dispose of butts, they discourage people from simply tossing them on the ground. This keeps sidewalks, parks, and public areas cleaner and reduces environmental pollution from cigarette filters.
The sand itself is functional. It's coarse and dry, which is effective for snuffing out the ember. You might also notice a small metal grating or ridges on the tray; this is for tapping the cigarette to ash it into the sand. While not a perfect solution—the trays can get messy when wet—they represent a practical compromise for managing smoking waste in shared outdoor spaces. So, next time you see one, you'll know it's a thoughtful piece of urban design aimed at promoting safety and tidiness.