That's an excellent question that many urban planners and park managers grapple with. There isn't a single universal number, as the optimal density depends on several key factors. A good starting point is to consider visibility and convenience. The general rule is that a person should be able to see the next trash can from their current location, often cited as a 30-meter (about 100-foot) visual range in high-traffic areas like entrances, playgrounds, or food courts. In quieter zones, this can extend to 50-75 meters.
The primary driver is pedestrian flow and activity nodes. High-density placement is crucial near benches, picnic areas, food vendors, transit stops, and sports facilities. For general pathways, spacing cans 50-100 meters apart is common. You must also analyze litter patterns—observe where waste accumulates naturally and place receptacles there. Consider the bin capacity too; high-traffic spots need larger or more frequent emptying, not necessarily more cans.
A strategic approach often involves zoning: high-density zones for active areas and lower-density for passive meadows or perimeter paths. The goal is to make disposal the easiest choice, preventing littering. Ultimately, it's about iterative observation—install a baseline, monitor, and adjust based on actual usage and cleanliness. Effective placement, coupled with regular maintenance, is far more critical than sheer quantity.