INFRASTRUCTURE OBSOLESCENCE AND DESIGN SERVICE LIFE

Infrastructure facilities generally have long service lifetimes. Major action is nevertheless eventually needed to overhaul, renovate, or sometimes demolish a facility that no longer provides satisfactory service. Sometimes obsolescence, brought on by changes in demands or technologies, motivates such action. Obsolete facilities—antiquated, old-fashioned, out-of-date—impose heavy burdens on their owners and users. Obsolescence, a concern throughout a facility's entire life cycle, reflects changed expectations regarding the function, profitability, or other dimension of performance that a facility is expected to provide. While such changes are primarily external, a facility's initial capabilities (e.g., durability of materials, flexibility of mechanical equipment) and how it is maintained influence the likelihood or timing of the onset of obsolescence. Obsolescence reduces the facility's service lifetime and for infrastructure may be the only meaningful technical basis for selecting a design service lifeti...