The Purple Guide to Health, Safety and Welfare at Music and Other Events — Venue & Site Design[1]
Summary
Sets out the audience capacity method. Figure 1 computes capacity as four converging streams — ingress (arrival profile, entrance widths, fill rate under search, queue capacity), holding space (site area reduced for sightlines and infrastructure, discounted by the lower of the P factor for physical condition and the S factor for safety-management quality), density (expected densities determined by risk assessment of the audience profile: 4, 3 or 2 persons per square metre), and egress (escape widths reduced by the largest single exit, evacuation rate risk-assessed, time-for-evacuation banded over 5, 5-10, over 10 minutes) — with the terminal rule that the lowest figure is the safest capacity. Escape rates follow the Green Guide 6th edition, based on BS EN 13200-1:2003: for 1.2 m width, 79 people per minute on a stepped surface (66 per metre width per minute) and 100 on the level (82 per metre width per minute); higher rates require specific justification, and the risk assessment must weigh alcohol, drugs and child buggies as factors slowing escape. Capacity includes staff, contractors, guests, performers and volunteers, not attendees alone. Site plans are gridded for emergency location-finding, version-controlled, and frozen once capacity is set and tickets sold, because later structural changes convert sold capacity into overcrowding.
So what
The 2-4 persons per square metre planning range is the standing-density figure the library lacked, and it sits between the 1 per square metre threshold at which crowd dynamics is defined as operating and the 4-plus territory where the crush literature places physiological danger — UK practice plans up to the bottom edge of the danger band and selects within the range by audience profile, not headcount. The P/S factor discount means a venue with poor safety management has a lower lawful capacity in identical square metres: a post-Hillsborough construct with no US analogue, where occupancy codes compute load from area and egress alone. The largest-single-exit discount and the lowest-figure-governs rule make capacity explicitly a minimum over three independent capacities; a venue can be egress-limited with holding space to spare. The egress constants terminate in a European seating standard rather than empirical crowd research, which is worth stating wherever they are cited.