BY NORMAN E. GRONER, Ph.D.
The World Trade Center attacks have given new impetus to the use of elevators during fire emergencies. Had elevators been unavailable to South Tower occupants, far more would have remained in the building when the second plane struck. Had elevators been readily available to firefighters in both towers, it seems likely that fewer emergency responders would have been needed for rescue operations and more would have been able to escape the buildings as conditions became transparently dangerous. Investigating the use of elevators is part of the National Institute of Standards and Technology (NIST) investigation, and I expect that corroborating and new findings will become available sometime in the future.
A decade ago, considerable attention was paid to this issue, including two professional symposia on the topic.1, 2 In general, there was broad agreement that elevators can be designed to continue safe operations during fire emergencies by increasing the reliability of the machinery and by protecting elevator lobbies and shafts against the intrusions of heat, smoke, and water. However, the elevator manufacturers and the fire service have largely resisted such changes. The elevator manufacturers were rightfully concerned that such “safe” elevators would be used in unnecessarily risky ways, endangering people and, not incidentally, exposing them to increased liability. The fire service rightfully expressed concerns over their use by nonprofessionals who would lack the training and equipment to deal with problems. While just as valid today, I believe that these concerns can and should be addressed. Elevators are simply too valuable a resource to be dismissed outright during building emergencies.
When used in conjunction with stairs, total evacuation times for tall buildings can be substantially reduced. (For documentation, see the article by Jake Pauls in this issue, as well as Pauls’ and colleagues article for the first elevator symposium.3) Elevators can be used to evacuate persons who cannot use stairs as a result of disability and injury. There is anecdotal evidence, which may be confirmed by the NIST investigation into the World Trade Center building disaster, that persons with disabilities and injuries, along with the emergency responders and civilians assisting them, died in disproportionate numbers on September 11. Even if fire-safe elevators are not used for evacuation, firefighters can use them for rapid vertical access for suppression and rescue operations. If evacuations are begun during the many minutes before emergency responders can commence their operations, the benefits are that much greater.
The engineering challenges of more reliable building elevators that can resist heat, smoke, and water are well understood, but the human interface and procedural challenges require much more attention and very careful thought and design. Failure is likely if we simply install fire-safe elevators without carefully considering the details of how people will use them.
DEFINING THE STRATEGIES FOR USING ELEVATORS IS ESSENTIAL
Decisions about the strategic use of elevators during emergencies4, 5 should be made before the designs for controls and operator interfaces for elevators are finalized. Examples of such decisions include the following: Who has priority access to the elevators? Will persons facing the greatest danger have first access, or will persons with disabilities and injuries be given highest priority regardless of location? Or will their use be restricted to firefighters, who need to quickly travel vertically to begin suppression activities? And most importantly, who will be operating the elevators, and who will be directing their use?
PROS AND CONS OF EXCLUSIVE FIREFIGHTER OPERATION
Many in the fire service resist the idea of civilians’ operating elevators during emergencies, even after the systems have been engineered to protect them against fire, smoke, and water intrusion. They argue with good reason that such systems are not failureproof and that operators need the equipment and training to deal with such emergencies. They also argue that civilians lack the training and discipline needed to run a coordinated and efficient rescue operation.
On the other hand, the arguments for allowing trained civilians to operate the elevators are also persuasive. Most importantly, seconds count during building emergencies, and a considerable amount of time can elapse before a fire department can respond, assess the situation, and begin rescue operations. During these critical minutes, elevators can be used to evacuate people who may otherwise suffer injuries or death, because they eventually were overcome by spreading fire or smoke after having been trapped or delayed while waiting to access crowded stairs or for rescue because they couldn’t use the stairs. Firefighters will have the option of taking over elevator operations when they are ready or leaving it in the control of civilian responders. Everything considered, my best guess is that the advantages of starting evacuations with trained building occupants are too great not to use elevators before emergency responders can take charge—but only if the strategies, operator interfaces, and training are carefully designed, executed, and maintained.
PROS AND CONS OF AUTOMATION
Control and routing of elevators during emergencies are of great importance and will require careful research and development. Of critical importance is the degree to which operations can and should be automated. Engineers often gravitate toward automation because it presumably eliminates human error, but deciding whether and where to automate is difficult. Automation increases systems complexity, which increases the probability of malfunctions. Additionally, problems can arise when people interact with automatic systems. Rather than eliminating human error, automation can have the unintended consequence of simply creating different types of human error.6 Automated systems, especially in such life safety critical functions, demand human supervision, but people find it inherently difficult to carefully track the status of a system when they are not involved in its operation. The result is that if they must assume command over the system, and they do not understand its status and mode of operation, mistakes are likely. Many such instances are documented in airplanes and industrial operations.
Other problems can arise when people either put too much trust in automated systems or do not trust them enough. Too much trust can lead operators to allow the systems to exceed the limits of their operation, and too little trust can lead operators to reduce the systems’ performance by assuming control of automated systems that were already performing well. Such difficulties are compounded by the inherently chaotic nature of emergencies, which can progress in unpredictable ways that the designers of the automated systems had not anticipated.
Despite the problems associated with automating systems, the automation of some functions may be of very great value. In the human factors field, this process of deciding which functions are better performed by machines is called “functional allocation.”7 An example might be the automatic lockout of staging areas where conditions are untenable or where reliable elevator operations are problematic. Similarly, interim lockouts could be automated so that elevators would not stop at lobbies where less endangered occupants are waiting, thus speeding the evacuation by allowing the elevators to operate as an express between endangered passenger pickup and discharge.
INTERFACE DESIGN REQUIRES CAREFUL RESEARCH AND DEVELOPMENT
All of us have abundant experience with simple devices, such as VCRs, telephone systems, and alarm clocks, where the interfaces are so poorly designed that we cannot figure out the most basic operations without studying the instructions. Controlling a bank of elevators so that the people at greatest risk are evacuated first while assessing the environmental status of elevators and staging areas requires a far more complex interface. Simply providing arrays of indicator lights and video screens will not work, because the great amounts of data will simply overload the operator’s information-processing capabilities. Instead, information displays should be based on “cognitive task analyses,” a set of human factors techniques used to describe the types of decisions operators must make and the information and mental demands they will need to make those decisions.8
TRAINING USING SIMULATIONS OF EMERGENCY OPERATIONS
To the extent that good design makes the operation of interfaces apparent, training needs are reduced. This is especially important in emergency systems, because they are not routinely used on a daily basis. “Transparency” is a goal of good interface design, meaning that the operators should be able to understand how to work the system without having to spend extra energy thinking about it. Nonetheless, some training is inevitable even when the interfaces are well designed. Training in the operation of emergency systems is often best accomplished by simulating emergencies. The capability of simulating emergency scenarios can be built into the design of emergency elevator systems, thereby greatly improving the likelihood that operators will be able to understand and operate the interfaces under a wide variety of situations. Alternatively, manufacturers could build simulators that copy the features of elevator cabs and control rooms, but this would require the expense of taking people off-site for their training.
“CIVILIAN” OPERATION OF EMERGENCY ELEVATOR SYSTEMS
Training is one of the important arguments against allowing civilians to operate elevators during emergencies. In recent years, some urban centers like San Francisco and New York City have been requiring building managers to hire professional emergency coordinators, often called “fire safety directors.” In addition to their responsibilities to educate and drill building occupants and emergency teams in evacuation plans, these professionals are often expected to coordinate emergency operations until the fire department can respond, assess the situation, and begin its own operations. Professional building emergency coordinators typically must pass a college-level curriculum to receive certification. Initiating and commanding emergency operations for a fire-safe elevator system would be an extension of their current responsibilities. Some people question whether people without backgrounds in the emergency response professions could perform such stressful duties without panicking, but the existing evidence tends to contradict this belief. During emergencies, people typically rise to the occasion and perform in full accordance with their assigned responsibilities, even when such experiences are not part of their backgrounds. Of course, this is assuming that they know what their duties involve and that they have the technological support needed to perform those duties, a result of the good planning, interface design, and training just described.
Elevators in tall buildings that can be safely operated during fire and other emergencies have great potential for improving emergency operations. Even if used solely by fire departments, suppression and rescue operations could be significantly improved. However, before emergency responders begin their operations, these systems could be used to especially great effect in evacuating occupants more quickly, to the very great benefit of those persons unable to easily descend stairs because of disabilities and injury.
Engineering the hardware to prevent intrusions of heat, smoke, and water is not the primary obstacle. The greater challenge is in the real-world use of these systems—in the strategic planning, interface design, and operator training that will enable the safe, effective, and efficient use of elevators during emergencies. I believe that installing protected elevator systems without attention to these concerns will result in an unacceptable risk to using the systems. However, by working out the details of strategic planning and tactics, the human factors of functional allocation and interface design, and appropriate training for operators, these systems will be entirely workable and will reduce the risk to building occupants and emergency responders.
- Symposium on Elevators and Fire Proceedings, American Society of Mechanical Engineers, New York, 1991.
- Elevators, Fire and Accessibility Proceedings, 2nd Symposium. American Society of Mechanical Engineers (ASME), New York, April 19-21, 1995.
- Pauls, J., E. Juillet, and A. Gatfield. “Elevator Use for Egress: The Human-Factors Problems and Prospects,” Proceedings of Symposium on Elevators and Fire, New York: American Society of Mechanical Engineers; 1991, 63-75.
- “Selecting Strategies for Elevator Evacuations,” Elevators, Fire and Accessibility, 2nd Symposium, American Society of Mechanical Engineers (ASME). Proceedings, New York, April 19-21, 1995, 186-189.
- Levin, B.M. and N.E. Groner, “Some control and communication considerations in designing an emergency elevator evacuation system,” Elevators, Fire, and Accessibility, 2nd Symposium, American Society of Mechanical Engineers, New York, NY; 1995, 190-193.
- Sarter, N. B., D.D. Woods, and C.E. Billings, “Automation Surprises.” In Salvendy, G. (ed.) Handbook on Human Factors and Ergonomics, 2nd Edition (New York: Wiley, 1997) 1926-1943.
- Sharit, J. “Allocation of Functions,” In Salvendy, G. (ed.) Handbook on Human Factors and Ergonomics, 2nd Edition (New York: Wiley, 1997), 301-339.
- Schraagen, J. M., S.F. Chipman, and V.J. Shalin. (eds.) Cognitive Task Analysis. (Hillsdale, NJ: Lawrence Erlbaum, 2000).
NORMAN E. GRONER, Ph.D., a consultant based in Santa Cruz, California, has worked in the human factors field for 25 years, much of it in the area of cognitive factors related to fire safety and emergency planning. After earning a doctoral degree in psychology from the University of Washington, he worked for the National Bureau of Standards, where he developed a method for calculating the difficulty of evacuating board and care facilities, later included as an optional method in the Life Safety Code for establishing required levels of fire safety requirements.
Among other activities, he has investigated human behavior during fires, conducted post-earthquake studies of organizational responses, written curricula for college fire safety courses, analyzed the feasibility of using building refuge areas and fire-safe elevator technologies, and worked on various code-writing committees and task forces. Groner coordinated the World Trade Center Evacuation Study Initiative, an ad hoc group of researchers, practitioners, and advocates who came together out of concern over the repeated failures to improve our knowledge of building evacuation as a crucial mitigation measure in emergencies and to encourage the dissemination and broad application of that knowledge.