On September 11, 2001, the world watch in horror as the United States experienced its worst terroristic attack that claimed thousands of lives and destroyed significant infrastructures in its wake. Not only this, catastrophic events of huge magnitude also claimed hundreds of thousands of lives- the earthquake that gave rise to a tsunami along the Indian Ocean coast in 2004; Hurricane Katrina that destroyed properties and killed people in the US Gulf coast while in 2005; earthquakes along the borders of India and Pakistan in 2005 that also killed hundreds of thousands of people; and most recently, earthquakes in China buried thousands of school children alive.
These natural and man-made disasters have awakened people’s consciousness to the importance of disaster management practices and how these government policies are implemented within their locality and area (Committee on Disaster Research in the Social Sciences, National Research Council, 2006). Public policies are also vital in ensuring that in times of disaster that involves a large number of people, these are practiced not only in the local level but also nationally and internationally (Committee on Disaster Research in the Social Sciences, National Research Council,2006; Committee on the Effective Use of Data, Methodologies, Technologies to Estimate Subnational Populations at Risk, National Research Council, 2007).
Today, there is an increasing need to address vulnerability and risk by using preventative design-related measures. This increasing catastrophe around the world that involves a large number of people emphasizes this need. Today, transport terminals to shopping malls to passenger ships or aircrafts have to deal with more and more people using these infrastructures and have to cope with the traffic created by these masses (Galea, E., 2003; Silvers, J., 2000). After the World Trade Center tragedy, the world has focused more on the importance of conducting evacuation simulation and the need to design buildings that will allow for more spaces that are efficient and comfortable in times of evacuation (Galea, E., 2003; Saloma, C. and Perez, G., 2005; Mahmassani, H., 2005). These well designed buildings will limit the time involved in queuing and avoid excessive congestion. Understanding pedestrian and evacuation dynamics encompasses understanding human behavior (Galea, E., 2003). As Galea, E. (2003) explains “clearly then, an understanding of human behaviour is key to both the development of pedestrian and evacuation simulation models and the meaningful application of those tools to shape the modern world” (p. vii).
The aim of this paper is to investigate the relationship and dynamics between human behavior and infrastructure design issues. This paper recognizes that different forms of infrastructure have to deal and service an increasing number of crowd. To achieve the aim of this research, the first part of this paper will explore the vulnerability factors and characteristics. This section will also seek to present whether vulnerability and risk can be reduced. Barriers to effective risk reduction will likewise be presented. The next part of this paper will investigate how development can reduce vulnerability. Capacity assessment or the identification of hazard exposure will also be reviewed. The last part of this paper will tackle the important steps that should be taken to mitigate vulnerability and reduce risk in large scale gatherings.
Vulnerability factors and characteristics (complex dynamics)
Disasters have “always involve the interaction of physical extremes…with the human system” (Alexander, D., 2002; p. 2) and encompass both direct losses and even indirect losses. For example, a minor earthquake may cause the collapse of a bridge that may start a chain of catastrophic events. With the direct loss to lives, an indirect loss caused by this disastrous event may include loss of employment or income affected by the destruction of the bridge. Resilience during disasters is an important process in order to limit the vulnerability of a community (Mason, B., 2006). It is imperative to note that vulnerability factors exist in crowd dynamics. For example, these factors include gender of those involved, age, economic background as well as ethnicity. In pedestrian dynamics, it is important not only to identify the vulnerability factors but also to understand how people behave in a crowd. Schadschneider et al. (2008) explained crowd behavior by first explaining that in crowded areas, jamming or clogging often occurs due to narrow exits or there are large counterflows and it is impossible to change direction because of the flow. These areas are called bottlenecks and present one area of vulnerability.
Alexander, D. (2002) noted that vulnerability and risk are complementary with the concept of hazard. Specifically, Alexander explains that risk is a product of hazard; the vulnerability of people and infrastructure to the hazard; and the extent of exposure of the people or buildings to the danger (see also Saloma, C. and Perez, G., 2005; Mahmassani, H., 2005; Templer, J., 1994).
Pedestrian dynamics has been studied extensively in recent times because of the crowd evacuation that occurred during the terroristic attack at the World Trade Center on September 11, 2001; the accidents that happened in Makkah during the annual holy pilgrimage and other world events that evoked social scientists to study pedestrian dynamics in depth (Mahmassani, H., 2005).
From these experiences, various researchers and scientists have concluded that vulnerability and risks can be reduced by applying the different models in crowd dynamics. While a number of evacuation models are applied and practiced in different countries in many situations (see for examples Avedrill, J. et al, 2005; Lam, W. and Cheung, C., 2000), Egress Modeling (see Avedrill, J. et al, 2005; Helbing, D. et al, 2002) is useful in evacuating huge crowds in large buildings. Discussion on how this is applicable will be explained in detail in the third section of this paper.
Barriers to effective risk reduction
Barriers to effective risk reduction might include the inability of building engineers or mall architects and designers or subway station builders to incorporate crowd dynamic modeling that will ensure the safety of the crowd in times of disasters or emergency (Saloma, C. and Perez, G., 2005; Mahmassani, H., 2005; Templer, J., 1994). Another barrier might be the failure of events managers to anticipate the magnitude of the crowd and provide enough exits during egress (Klupfel, H, 2005) . Third, a possible barrier to effective risk reduction is failure of building managers to implement proper guidelines on building evacuation and safety and the lack of evacuation drills by the occupants of their buildings. Fourth, another possible barrier includes the lack of information drive and education to the crowd on the proper action in times of emergencies.
Despite the possible barriers cited above, vulnerability can be reduced with development. Compared to third world countries, highly developed countries have implemented and integrated systems and models that will make their buildings safe and train the occupants on how evacuate buildings safely (see Avedrill, J. et al, 2005; Lam, W. and Cheung, C., 2000). For example, it has been noted during While these countries cannot wholly protect their citizens from terroristic attacks, they are in a position to implement guidelines and practice these guidelines not only in buildings but in crowded areas too (see for example Mason, B., 2006; Bowdin, G. et al, 2006).
Capacity assessment and the identification of hazard exposure
Understanding how a crowd behaves is vital in assessing the capacities of responders during emergencies and in the creation of evacuation models (Mason, B., 2006). Human behavior is considered to be complex (Lee, R. and Hughes, R., 2006) and this is reflected on the number of models that have been created just to simulate human behavior in a crowd. In an effort to provide a realistic view of human behavior, different models have been used to depict the how a crowd reacts in different situations (Independent Street Arts Network, 2005). As an example, Galean, E., 2003 cited that to date, the Fire Safety Engineering Group (FSEG) from the University of Greenwich have acknowledged that currently engineers all over the world are using more than 40 models for evacuation from building, passenger trains, aircrafts and ships.
To identify the different hazards a crowd faces, it is important to identify structural components and safety measures present in a building or establishment (Health and Safety Executive, 1998, 1999, 2000). Crowd dynamics such as collective effects of a crowd behavior should also be taken into consideration (Schadschneider et al, 2008; Helbing, D. et al, 2002). For example, lane formation or counterflow should be studied in order for the opposing flow of pedestrians will have no difficulty in moving in opposite directions. To counter the effect of lane formation, large lanes or multiple lanes are to be created to provide comfort and safety for the crowd (Pheasant, S., 1998). Crowd disaster could also be prevented by providing larger exits to avoid competition of access to a safer space or to an exit point (Lee, R. and Hughes, R., 2006).
Important steps that should be taken to mitigate vulnerability and reduce risk in large scale gatherings
Building evacuation presents a real challenge to a disaster management team. However, building evacuation can be greatly improved by first, designing a system that would not only allow safe but also rapid egress (Avedrill, J. et al, 2005; Lam, W. and Cheung, C., 2000). Second, it is important to educate and prepare the occupants of a building for evacuation in times of emergency (Lee, R. and Hughes, R., 2006). It is also necessary that the company has a set of guidelines and an emergency evacuation plan to be used in times of emergency (see for example Mason, B., 2006; Bowdin, G. et al, 2006). Incorporation of best practices during full and partial evacuation into the building’s evacuation guidelines will also support the safety of the crowd. Reaction to different conditions (for example in the case of a fire, earthquake, massive power failure, terrorism, etc.) and how evacuation will be carried out in detail from the occupant’s floor or office to the point where they are considered to be safe should also be established (see Averill, J. et al, 2005; Saloma, C. and Perez, G., 2005). Regular emergency drills will be an important tool in achieving the aim of safe building evacuation.
In cases of very tall buildings, it is vital to design an egress system that will accommodate flow of occupants as well as the counter-flow of emergency responders (Averill, J. et al, 2005; Saloma, C. and Perez, G., 2005). Occupants who are mobility challenged should also be considered in designing this egress system in tall and populated buildings (Bowdin, G. et al, 2006; Tubas, J. and Meacham, B., 2007). Elevators, in times of emergency, are in most cases not suitable for exit (Templer, J., 1994; Mason, B., 2006; Bowdin, G., et al, 2006), but staircases are used instead. To accommodate the flow of occupants, the staircases should be designed to hold a maximum number of people as well as provide protection in cases of impacts, earthquakes and the likes (Silvers, J., 2008). Lastly, high-technology evaluation techniques should also be employed together with more resilient and hardened elevators, better staircases and devices that will aid occupants during their navigation to an area that is already considered safe (see Averill, J. et al, 2005; Saloma, C. and Perez, G., 2005).
Meanwhile, simulation of pedestrian flow is also applicable in the egress from a large event such as a football or soccer stadium (Klupfel, H. 2005). Safety in times of emergencies during big events can be averted by implementing sound guidelines that will effectively evacuate the crowd and lessen or prevent casualties in the event of a stampede (see Alexander, D., 2002; Klupfel, H., 2005). Egress time is also critical during emergencies in subway stations (Koennecke, R. and Schneider, R., 2005). Guidelines set by subway stations to evacuate their passengers during disasters should be well-developed to ensure their passengers’ safety (Konnecke, R. and Schneider, R., 2005; Helbing, D., et al, 2002).
Various models are also carried out to understand pedestrian dynamics in other large areas such as the mall, city center establishments, train or airport waiting stations and infrastructures for walking (Schadschneider, A. et al, 2008).
Summary and Conclusion
Reduction of vulnerability and risk during large scale gatherings is possible with the application of crowd dynamics or pedestrian simulation models. Second, the implementation of safety guidelines along with better building and infrastructure designs ensure the crowd’s safety. Third, there is a need for re-examination and continual evaluation of how a crowd behaves during emergencies in highly dense areas in order to create better simulation models that will be useful in many countries around the world. Fourth, while engineers and others who design the safety guidelines for large gatherings have contributed to the safety of the crowd, it would noteworthy that more research on the social and psychological aspect of crowd dynamics should be conducted to have more efficient safety guidelines in times of emergencies or disasters.