Honestly, they can work—but not automatically, and not as often as cities hope. In public spaces, a separate compost compartment is only one part of the system. The real question is whether the whole setup is designed for messy human behavior, because that is what decides if the compost stream stays clean enough to be useful.
From what I’ve seen, the biggest problem is contamination. People are often in a hurry, the labels are confusing, or the bin looks like a regular trash can with one extra flap. If someone throws in a coffee cup, a plastic wrapper, or a bag that is not compostable, the whole load can be downgraded or sent to landfill. That is why I would judge public compost bins by contamination rates, not by how good they look in a sustainability report.
They tend to work better when the design is simple and obvious: clear color coding, real examples of what goes in, lids that are easy to use, and bins that are emptied often enough that they do not overflow. Cleanliness matters more than people admit. A smelly, messy bin invites misuse. Collection also has to match the promise. If the truck crew mixes compost with general waste, the separate compartment is basically theater.
The strongest examples I’ve seen are where public bins are part of a wider system: compostable packaging rules, staffed or regularly audited stations, feedback loops, and a local composting facility that can actually accept the material. In those cases, separate compost compartments can reduce waste and teach better habits. Without that support, they often become just another bin people ignore.
So yes, urban trash bins with separate compost compartments can work in public—but only as a carefully managed system, not as a lone green label on a street corner. When cities get the signage, maintenance, collection, and contamination control right, they are worth it. When they don’t, the compost compartment is usually just a hopeful idea with a lid.