Research on the effect of life cycle gaps on life cycle cost of urban infrastructure engineering

Life Cycle Cost optimization has become a new focus of urban infrastructure engineering economic study. This paper shows the replacement reasons and preferences related to the different type of life cycle by studying literatures. It is clear by analyzing a basic LCC model that sensitivity of the LCC functions on life cycle gaps is less than the discount rate when life period is longer, so the life cycle seems to be a secondary factor for LCC optimization. But some special replacement projects have been found by an empirical study on some subway engineering assets. The results have demonstrated that the deviation between predicted and actual life greatly affected the LCC of subway engineering, and these gaps mainly contributed the recurring investment to the LCC. A new concept of built environment life cycle is put forward.