Accessibility and the Intelligent Egress System

Jan. 1, 2004

New applications and integrations of existing technologies with fire protection/life safety systems could improve evacuation and rescue assistance for disabled persons. New accessibility and life safety features will likely be driven by innovation and a continued trend towards the establishment of higher standards of care in the realm of accessibility and life safety.

Equivalent Levels of Safety

Building code requirements concerning accessibility and egress provide physically challenged occupants with information and elements that safely direct them to accessible exits or designated evacuation assistance areas.

The need to provide equivalent levels of life safety for persons with mobility, visual and hearing impairments challenges security to expand the capabilities and integration of the fire protection/life safety features currently required in buildings. Some of these elements might include systems that incorporate increased levels of distributed intelligence; systems that dynamically observe, optimize and direct evacuation flows based upon building conditions; wireless communications systems that tailor communications to the intended recipients' needs; and wireless positioning information to help facilities personnel and emergency responders locate mobility, visually and hearing impaired persons in emergencies.

Evacuation Assistance Challenges

Physically challenged occupants may move slowly in evacuations, so providing technology that can help them find their way to an exit quickly may improve response time. When response times are decreased, building occupants are exposed to emergency hazards for less time, thereby increasing their chances of survival and reducing their likelihood of injury. If these occupants are warned in advance of the dangers they might face along certain egress paths, they will make better choices. The result will be potential decreases in their hazard exposures. An intelligent egress system that informs occupants of the best decisions to make during an emergency by drawing upon monitored building conditions could provide additional levels of protection and reduce evacuation and rescue assistance times for disabled persons.

Areas of Evacuation Assistance

Areas of evacuation or rescue assistance are protected areas provided to disabled persons awaiting the assistance of trained emergency personnel. The areas may offer smoke-proof enclosures, two-way communication capabilities, proper identification of evacuation assistance locations, alarms and emergency warning systems. These features are intended to provide safe areas within buildings that are protected from fire, smoke and toxic products of combustion. Additionally, wayfinding and communications features help people locate these areas, allow them to communicate between these areas and the primary entry, and alert them to danger through alarms and emergency warning systems.

Although the building code requires specific life safety features such as areas for evacuation assistance, some jurisdictions allow the omission of these areas in buildings with supervised automatic sprinkler systems. Automatic sprinkler systems have proven effective in controlling fires and protecting the occupants of a building from harm. When they are used as a basis to justify the omission of areas of evacuation assistance, mobility, visually and hearing impaired persons rely upon their faith in modern engineering and timely evacuation or rescue assistance in the event of a fire. In these circumstances building officials often ask, "If areas for evacuation assistance are not provided, what additional fire protection/life safety features are proposed to ensure that disabled occupants are reasonably protected?"

Timed Egress Models

Timed egress models are powerful analytical tools used to estimate the times required for occupants to evacuate a building during various emergency scenarios. Factors such as number of exits, exit capacities, number of occupants, distance to exits, occupant notification and occupant pre-movement times are considered. The decreased costs of computing technology and software developments allow timed egress to be used to effectively and efficiently model the dynamic behavior of a building egress system under varying conditions. Although these tools are now used theoretically, they could be applied to actual (as opposed to virtual) buildings to enhance life safety.

In theory, timed egress models optimize egress times based upon the shortest path to an exit; although this optimization mimics behavior, it does not produce a model of the most efficient exiting scenario possible. The application of timed egress models to actual buildings would facilitate the observation and direction of occupants during emergency conditions to optimize flows. In other terms, a "real-time" optimized exiting model would receive inputs and provide outputs based upon actual building conditions in order to enhance the survivability of building occupants. The model would then provide useful information and direction to evacuees and persons seeking rescue assistance based upon a comprehensive picture of the building conditions during evacuation. This could reduce total evacuation times, reduce hazard exposure and provide useful information to persons seeking rescue assistance and rescue personnel.

How do timed egress models consider accessibility? Although research concerning the ability of mobility impaired persons to egress has shown that the number of changes in direction can add considerably to evacuation times, current timed egress models do not completely address the varied abilities of mobility, visually and hearing impaired persons. A seemingly shorter escape route with more changes in direction can result in greater evacuation times than a less circuitous but longer route to an exit. Additionally, occupants often attempt to egress via the nearest exit even though significant bottlenecking and queuing may result in delays in egress times.

Wireless Technology

Another accessibility and egress life safety feature that might be of interest involves the ability to locate persons needing evacuation or rescue assistance. During emergency situations, individuals providing evacuation or rescue assistance need to quickly assess a situation and prioritize their responses accordingly. The ability to quickly locate individuals with special needs and assess their needs based upon emergency conditions within the building could be extremely helpful.

Wireless technologies could provide this ability to locate individuals, speed the response times of rescuers, provide communication links to these individuals and provide input to timed egress models to optimize egress for these persons. Additionally, the ability to locate disabled occupants quickly and make decisions about their safety based upon observed conditions could reduce occupant response times and reduce occupant travel times to a place of safety.

This communication feature would be particularly beneficial to individuals visiting large high-rise buildings or other facilities with which they were unfamiliar. When provided, two-way communications are typically managed at specific areas of evacuation assistance. A disadvantage of these fixed locations is they limit communications to and from specific locations within a building. Untethering these communication features with wireless communication capabilities would permit the communications to take place in locations other than designated areas of evacuation or rescue assistance.

Integrated Intelligent Egress and Communication System

The integration of aspects of an intelligent egress system with untethered communications would enable mobility, visually and hearing impaired persons to benefit from building intelligence that was targeted to their specific needs. Some of these communication features could be voice automated and integrated with the fire alarm system. Valuable time preceding the arrival of emergency responders could be utilized to proactively direct the targeted individuals with information that assists their decision-making processes. Some of this information could be based upon data processed by the fire alarm monitoring system. Voice synthesis would enable the fire alarm system to begin timely proactive communications to intended recipients before facility personnel or emergency responders initiated communication with these occupants. Essentially, occupants could begin to take corrective action that was more specific and responsive to actual building conditions.

When installed, addressable smoke and heat detectors provide fire alarm monitoring systems with significant amounts of information regarding conditions in various parts of a building. The presence of heat and smoke are common conditions monitored by these detectors. An additional level of protection can be provided by intelligent detectors with embedded algorithms that further reduce detector response time by anticipating unfavorable developments within a building and promptly reporting these to the fire alarm panel. The combination of information provided by intelligent addressable detectors and the ability to locate occupants requiring special assistance is a powerful tool. These data points can converge to further close the gap on response times.

As was previously discussed, occupants attempting to egress a building often take the most direct route to an exit even though that route may not be the optimal choice. Similarly, if individuals knew they had viable exiting or rescue assistance alternatives they would likely act on those decisions in a manner that improved life safety. Moreover, they could take proactive measures before emergency responders arrived.

In emergencies, disabled persons seeking evacuation or rescue assistance could benefit from intelligent fire protection/life safety systems that employed features of distributed intelligence, dynamic observation, optimized and directed evacuation flows based upon building conditions, communications systems that tailor communications to the intended recipients' needs, and positioning information for the use of facilities personnel and emergency responders to locate them. These features would utilize technologies that currently exist and would leverage the life safety system capabilities currently provided in many buildings. The decision to move in this direction would be innovative and consistent with the trend towards the establishment of higher standards of care in the realm of accessibility and life safety.

Mark Budzinski, CBO, is a consultant of Rolf Jensen and Associates Inc., a global fire protection engineering consulting firm. He is a member of the National Fire Protection Association, the International Conference of Building Officials and an Associate of the American Institute of Architects.