of the role each structure and system element serves in the proper functioning of the urban system is important to address the robustness, resilience, and sustainability of the urban system.

Real hazards and risk to humans in the underground exist, and engineers have been largely successful in addressing many of them. Earlier chapters of this report looked at how urban utilities and systems are highly integrated and therefore interdependent. This chapter addresses human-technical system relationships, human response to hazards faced in the underground, and the hazards and risks related to human use of underground space. This chapter recognizes the people in the underground and considers the engineering necessary to keep them healthy while also contributing to sustainability. The presence or absence of naturally occurring phenomena in the underground may pose risk to humans. Gases, radiation, temperature, water, and the lack of oxygen are among inherent hazards to human underground occupation. Other hazards to people or infrastructure may result from human activity that creates, adds to, or intensifies naturally occurring risks. These include risks associated with fire and smoke, hazardous materials, intentional or accidental explosions, structural failure, human failure, and extreme events.

It is important to fully understand the hazards and risks because a very key part of long-term success (i.e., sustainability) of the underground is the ability to regulate underground construction and activities to ensure minimum safety. Although various standards exist that govern, principally, fire safety for underground transportation and building and industrial facilities, there is a need for a more comprehensive approach to safety against all hazards for all types of underground facilities. The remainder of this chapter explores this need.


To create a functioning, sustainable, urban system that effectively links its social, technical, and governing elements, the relationships between technologies, the people that construct, operate, and use those technologies, and the social structures that govern them must be understood. In the manufacturing realm, this area of research is referred to by several names including human factors, human engineering, engineering psychology, and ergonomics. Licht and others (1989) analyzed numerous definitions for terms and areas of study related to or synonymous with “human factors” research and found that most definitions implied a multidisciplinary approach including concepts related to behavioral science; human performance capacity; manpower, personnel, and training; and biology, physiology, and medicine.1 Information obtained through the study of human factors can be applied to the “design of tools, machines, systems, tasks, jobs,


1 Biology, physiology, and medicine were more common in definitions associated with ergonomics (Licht et al., 1989).

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