Journal of Infrastructure Systems

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 Obsolete facilities—antiquated, old-fashioned, out-of-date—impose heavy burdens on their owners and users.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 lifetime. This paper characterizes obsolescence as a concern for facility design and management, explores its sources, analyzes its impacts on infrastructure performance, and discusses how consideration of obsolescence might influence key infrastructure design and management parameters such as design service life and maintenance policy. The study of obsolescence can yield strategies for more effective infrastructure management, but warrants a multifaceted blending of theoretical analyses and practical observations.

Field tests of buried PVC (polyvinyl chloride) water mains have been undertaken to identify the mechanisms of pipe-soil interaction. Temperatures and strains on the pipes have been continuously measured since late 1993 for over two years. In a theoretical study, a simplified Winkler model was previously developed to simulate the response of a jointed pipe subjected to temperature and water pressure changes. The objective of this paper is to substantiate the theoretical understanding of responses of stresses and strains of the jointed pipes through comparative study of the field measurements and theoretical analyses. In general, good agreement was found between the predicted and measured strains, which supports the notion that the development of the strains is mainly a consequence of the seasonal pipe temperature variations. Possible reasons for some deviation between the predicted and measured strains are analyzed.