NFPA Journal

As pandemic-related restrictions are lifted around the world, and as large venues such as stadiums, arenas, and ballparks reopen to full capacity, the safety challenges that come with the presence of large crowds must not be overlooked.

That was evident on April 30 in Israel, when an annual religious celebration turned into a tragedy. Tens of thousands of people had gathered in Meron, a small village in the north of the country, for Lag B’Omer, a Jewish religious festival. At one point, a large number of attendees attempted to move toward exits following a festival event. But the walkways, passageways, and other egress routes in the tightly packed festival area could not accommodate the crowds, and people began to trip and fall as they tried to make their way out. The massive crowd behind them pushed ahead, causing a fatal crowd crush. Forty-five people were killed and more than 150 were injured. (For more on the dynamics of crowds at events like Lag B’Omer, see “In My Tribe.”)

NFPA 101®, Life Safety Code®, contains provisions that help ensure the safe and orderly movement of crowds during an emergency. When these safety protocols and features are neglected, it can have a drastic impact on the efficiency of egress response during events such as fire or other emergencies.

In areas of assembly occupancies larger than 10,000 square feet (930 square meters), the occupant load cannot exceed one person per 7 square feet (.65 square meters). This limit is in place to avoid overcrowding, which adversely affects the movement characteristics of the occupants and the efficiency of egress travel. Where occupants are crowded into a space too tightly, walking becomes a shuffle; further crowding can lead to a complete “jam point” such that all movement by occupants comes to a stop.

Where the occupant load of an assembly occupancy exceeds 6,000 people, a Life Safety Evaluation (LSE) is required. The evaluation recognizes that fixed protection and suppression systems alone do not ensure safe egress where large numbers of people are present. The evaluation must include an assessment of a minimum of 10 conditions as listed in Chapter 12 and 13 of the code. A new assembly venue subject to an LSE must be assessed prior to construction to ensure that the needed physical elements are part of the design. Also, facility management must be evaluated prior to building occupancy. The LSE provisions help facilitate better communication among the designers and those who manage the facilities after construction. Similarly, the LSE provisions for existing assembly occupancies include requirements for building systems and facility management assessments, a life safety narrative, floor plans, engineering analysis and calculations, operational plans, and a systems reference guide. Extensive details also exist in Annex A material in NFPA 101.

Every assembly occupancy, new or existing, is required to have a main entrance/exit. This concept accounts for occupants that are more likely to egress a facility though the same door(s) they used to enter it. In some cases, the main entrance/exit in new assembly occupancies must accommodate up to two-thirds of the total egress capacity, while in other assembly occupancies it can account for half the total.

Where there is no well-defined main entrance/exit, exits are permitted to be distributed around the perimeter of the building, provided that the total exit width provides not less than 100 percent of the width needed to accommodate the permitted occupant load. This concept acknowledges that some assembly occupancy buildings, such as large sports arenas, have no well-defined main entrance/exits; occupants enter the facility via one of multiple main entrances/exits. Under emergency egress conditions, all occupants will not attempt to use one common group of entrances/exits, because some occupants are familiar with certain entrances/exits while other occupants may be familiar with different entrances/exits. In such cases, it is the intent that egress width be distributed among the various exits without any one exit being required to provide 50 percent of the egress capacity.

In new assembly occupancies, where the floor area of auditoriums and arenas is used for assembly occupancy activities/events, not less than 50 percent of the occupant load can have means of egress provided without passing through adjacent fixed seating areas. This requirement of the code is intended to reduce the amount of merging and sharing of means of egress by persons in fixed seating areas and those who are forced to travel from the arena floor up into the seating sections to egress the building. Regardless of where in the assembly occupancy someone might be located, access and egress routes must be maintained so that crowd management and security personnel, as well as emergency medical personnel, are able to reach any individual at any time without difficulty.

Emergency Action Plans (EAPs) are also critical components of life safety in assembly occupancies. These plans must include a minimum of 18 items as listed in NFPA 101. The facility’s EAP must be submitted to the AHJ for review and should be reviewed and updated as required by the AHJ.

Finally, all assembly occupancies must include a minimum of one trained crowd manager or crowd manager supervisor. Where the occupant load exceeds 250, additional trained crowd managers or crowd manager supervisors are required at a ratio of one for every 250 occupants. Those designated as a crowd manager or crowd manager supervisor must receive approved training in crowd management techniques, and they must also understand the required duties and responsibilities specific to the venue’s emergency plan. The procedures for providing trained crowd managers must also be part of the written emergency action plan.

Managing crowds is critical to occupant life safety during a fire or other emergency. Active and passive fire protection systems, recognizing and mitigating risk, applying special building design features, and a proactive plan and implementation for crowd management and emergency procedures are all important components of a crowd-management strategy that will help ensure occupants at large-capacity venues remain safe and under control during emergencies.

KRISTIN BIGDA is technical lead for Engineering Technical Services at NFPA. NFPA members and AHJs can use the Technical Questions tab to post queries on NFPA 101 at nfpa.org/101. Top photograph: George Groutas via Wikipedia