If your goal is to prevent people from stretching out and sleeping on a public bench, you’re looking for what streetscape suppliers often call a center-armrest bench or intermediate-armrest bench. My recommendation is to start with a commercial metal or wood-slat bench that can be ordered with a third armrest in the middle. Brands like Victor Stanley, Maglin, Landscape Forms, and Forms+Surfaces offer outdoor benches with optional center armrests or configurable armrest spacing. For a durable, low-maintenance option, choose powder-coated aluminum or galvanized steel slats with stainless steel hardware.
If you already have benches, retrofit armrest dividers are the fastest and cheapest fix. They bolt or clamp onto the existing seat surface and create a physical barrier in the middle. Look for “bench armrest divider” or “anti-sleep armrest” products from site-furniture suppliers. Space them about every 40–50 inches so the bench still allows normal sitting but prevents someone from lying flat.
My top pick for a new installation would be a slatted metal bench with the center armrest integrated into the frame rather than bolted on. It looks more like standard street furniture, is harder to remove, and holds up better to weather and vandalism. Also check local accessibility codes and public-works standards before you install anything, since some cities regulate public seating dimensions and placement.