a. Research the state of practice and best practices related to safety systems (e.g., hazard detection, notification, ventilation, fire suppression, emergency egress, and system integration). Develop appropriate minimum safety system requirements to incorporate into national-level guidelines and standards.
b. Compare international underground safety codes and guidelines with those applicable in the United States to identify inadequacies and guide future practice, recognizing existing efforts in this area (e.g., by the Federal Highway Administration).
Public acceptance and use of underground space will increase if underground infrastructure is more convenient and comfortable to use. One design challenge is long-range planning that incorporates strong connectivity within underground systems and with surface systems. This means creating usable reasonably connected underground systems that limit pedestrian travel time and lengthy vertical movement by stairs, escalators, or elevators. However, existing building codes may not be flexible enough to accommodate the types of design that increase convenience.
Building codes exist to protect the health and safety of those constructing, operating, or using infrastructure, but their slowly evolving nature leaves little room to benefit from evolving technologies. Further, existing safety codes, regulations, and standards designed to address known risks above ground are often inadequate for large-scale, sustainable development of the underground. Largescale public use will require development of new and updated safety regulations that specifically address risk of the underground and activities (occupancies) therein.
Allowing variation in design based on better understanding of how to create safe but interesting and enjoyable underground space without greatly increasing costs and space requirements remains a challenge. Incorporating more human factors engineering into underground and urban system design and operation may improve the underground for safety, productivity, and aesthetics. Research into new materials and their behaviors, combined with risk assessments and management activities that incorporate, for example, provisions for emergency evacuations, rescue, and recovery would benefit the underground environment during normal operations, as well as during and following stressful events. Identifying and countering negative perceptions can be as important as safety and technical challenges and require their own research focus.