Sustainability is dependent on more than having enough clean water, food, and material goods. As urban areas grow, strategic growth of infrastructure systems is also necessary to allow for efficient and sustainable delivery of water and sewerage service, food, energy, industrial and commercial goods, and information. Locally created products or services need to be transported or exported, other goods need to be imported, and wastes need to be removed. Physical infrastructure systems are thus critical to the urban system of systems and underpin both a sustainable economy and quality of life.
How does the growth of urban populations, the expansion of urban lands, and their associated facilities and infrastructure enhance or hinder the provision of essential materials and services and the creation of stable, sustainable, socially desirable urban communities? What is the role of the underground? As described in Chapters 1 and 2, the underground is best thought of as a resource designed and managed using a system of systems approach to achieve the most sustainable solutions. Infrastructure is a substantial shaping force in urban and regional development. In developed areas, underground infrastructure may offer one of the few acceptable ways to encourage or support the redirection of urban development into more sustainable patterns because new support infrastructure can be added relatively unobtrusively. A well-maintained, resilient, and adequately performing underground infrastructure is essential to future sustainability of cities. Much, however, can be done to improve the sustainability aspects of underground facilities themselves.
Urban sustainability will be more likely if it becomes the expectation among urban planners and managers that the urban setting includes the space resources both above- and belowground, and that both contribute to the healthy functioning of a city. This chapter discusses some urban resources and their potential roles in a holistic accounting of urban systems; the following section specifically highlights certain uses of the urban underground that greatly contribute to urban sustainability.
Sustainability planning requires forethought regarding operation and maintenance issues for the entire life cycle of the infrastructure. Allowing ease of access for maintenance, repairs, and upgrades is a means of insuring that such work can be completed at lower costs. Experience from subway construction and other large underground works has led to interest among some subsurface utility providers in combining utility services in common utility tunnels—often termed “utilidors” (or “galleries” in Europe; see Box 1.4, Figure 2 for an example of a utilidor) (APWA, 1971). Utilidors provide continuous maintenance access