Tone of voice isn’t just verbal. People can pick up cues from the surrounding environment. Saying no can be effective and communicate clearly without being harsh. This selection of barriers all communicate effectively and clearly delineate boundaries, letting you know the go / no-go areas without any additional verbal information. They also fit in with the surrounding area naturally and don’t make you feel cut off from seeing beyond the barrier.

Above: Elephants Delicatessen at closing time, PDX airport, USA

Gate for archeological site at Calle de la Canuda, Barcelona, SPAIN:

Portland Zoo wildlife exhibit, Portland, Oregon, USA: