Recent world events have demonstrated the need for increased security measures and the ability to evacuate large numbers of people efficiently. Long lines and handheld metal detectors have become familiar sights at the entrances to stadiums, arenas and other large places of assembly.
In most buildings the security and life safety systems work toward opposite goals. The goal of the security systems is typically to limit access to areas of a facility, while the goal of the life safety systems is to allow people to evacuate the building as quickly as possible via multiple remote exits. In few occupancies is this apparent dichotomy of goals more evident than in large-assembly occupancies such as stadiums and arenas.
Event security at large venues such as stadiums and arenas is extremely complicated. Security personnel and systems must maintain controlled access to sensitive areas while allowing thousands of people to enter and use the facility. Simultaneously, the security systems and personnel must be able to evacuate the occupants in a quick and orderly manner. This article will serve as an introduction to egress design for security professionals, to allow them to better understand the baseline requirements for the design of fire protection and life safety systems.
Both the model codes and NFPA 101 ? Life Safety Code require that areas or levels serving more than 1,000 people be equipped with at least four remote exits. This is required to minimize the impact of one or more exits becoming obstructed in the event of a fire emergency.
Occupants are not likely to be familiar with their surroundings when visiting a large-assembly occupancy. It is normal human behavior for them to attempt to exit the building via the same route by which they entered it. Thus, an emergency could potentially lead to queuing at egress choke points if proper precautions are not taken. To address this situation, the model building codes and the Life Safety Code require all assembly occupancies with an occupant load greater than 300 persons to have a main entrance/exit that provides sufficient capacity for at least 50 percent of the building's occupant load. The remainder of the required exits should then be evenly distributed throughout the facility.
Generally, the sheer size of stadiums and arenas makes it impractical to have a single, defined main exit that is sized for half of the occupant load. To meet the requirements, the main exit of a stadium would have to be large enough to accommodate more than 35,000 occupants. Using standard requirements for the provision of exits, this would require approximately 160, 44-inch-wide doors for the main exit alone.
In deference to this impracticality, the codes include an exception that states when there is not a well-defined main exit, the exits may be distributed around the perimeter of the building provided that they are sized to accommodate the total occupant load that they serve. This design approach helps to minimize the number of choke points in the egress system and reduces the impact of an exit being unavailable in an emergency condition.
The model building codes and the Life Safety Code prescribe an exit width of 0.2 inches per building occupant for horizontal exit components (i.e., doors, corridors, and ramps) and 0.3 inches per building occupant for vertical exit components (i.e., stairs). These measurements stem from a performance criterion that requires that occupants be able to exit the building or floor within 3.5 minutes (SFPE Handbook, Sec. 3, Ch. 13, ?Movement of People? by Jake Pauls). While these requirements serve most occupancies well, use of the prescribed 0.2- and 0.3-inch egress width factors in stadiums and arenas can result in enormous stairs, ramps, and banks of doors that might not have an appreciable effect on the overall life safety rating of the facilities. Also, with the occupant loads expected in these types of buildings, a 3.5-minute exiting time is an unrealistic benchmark.