That's a really interesting and practical question. It gets to the heart of how physical design can influence public behavior. From my observation and reading on urban design, the short answer is: yes, making openings smaller can be a helpful deterrent, but it's rarely a complete solution on its own.
The logic is straightforward. A standard large opening invites people to discard not just a coffee cup, but also bags of household waste, construction debris, or even small furniture. By reducing the aperture to a slot or a mail-slot style opening, you physically prevent the insertion of oversized items. It clearly signals that the bin is for pedestrian litter—wrappers, bottles, cans—and not for bulk disposal. This "defensive design" or "hostile architecture" principle nudges people toward proper disposal methods for larger items.
However, there are important trade-offs to consider. Excessively small openings can frustrate legitimate users. Someone with a few items in their hands might struggle, potentially leading to littering right beside the bin. They can also make emptying the bins more difficult for sanitation workers if the design isn't carefully planned.
The most effective strategies combine physical design with other measures. This includes:
* Clear Signage: Labeling bins with what is acceptable.
* Adequate Capacity & Frequency: Ensuring bins are emptied often so they don't overflow.
* Accessible Legal Alternatives: Providing easy, affordable options for bulk waste drop-off.
* Strategic Placement: Putting bins in high-foot-traffic areas where they are needed most.
So, while smaller openings are a smart, low-tech tool in the toolbox to discourage opportunistic illegal dumping, they work best as part of a broader, thoughtful waste management system. The goal is to guide behavior without making legitimate use a hassle.