Crowd Density Grade | Crowd Density Range (Indoor; Outdoor) | Status Description |
I | di ≥ 2.8; do ≥ 3.8 | Higher Security risk; serious emergency |
II | 1 ≤ di < 2.8; 1.33 ≤ do < 3.8 | Overcrowding; too dangerous |
III | 0.54 ≤ di < 1; 0.72 ≤ do < 1.33 | Interaction; congestion sprouts; controllable |
IV | di < 0.54; do < 0.72 | Crowds move freely, slowly, and smoothly |