Life-Cycle Costing Applications and Implementations in Bridge Investment and Management

University dissertation from KTH Royal Institute of Technology

Abstract: A well-maintained bridge infrastructure is a fundamental necessity for a modern society that provides great value, but ensuring that it meets all the requirements sustainably and cost-effectively is challenging. Bridge investment and management decisions generally involve selection from multiple alternatives. All of the options may meet the functional demands, but their life-cycle cost (LCC), service life-span, user-cost, aesthetic merit and environmental impact may differ substantially. Thus, life-cycle analysis (LCCA, a widely used decision-support technique that enables comparison of the LCC of possible options), is essential. However, although LCCA has recognized potential for rationalizing bridge procurement and management decisions its use in this context is far from systematic and the integration of LCCA findings in decisions is often far from robust. Thus, the overall objective of the work underlying this thesis has been to contribute to the development of sustainable bridge infrastructures while optimizing use of taxpayers’ money, by robustly incorporating life-cycle considerations into bridge investment and management decision-making processes.The work has introduced a full scheme for applying LCCA throughout bridges’ entire life-cycle. Several practical case studies have been presented to illustrate how an agency could benefit from use of a bridge management system (BMS) to support decisions related to the management of existing bridges and procure new bridges. Further developments include a comprehensive approach incorporating a novel LCCA technique, “LCC Added-Value Analysis”, which enables procurement of the most cost-efficient bridge design through a fair design-build (D-B) tendering process. A further contribution is a novel, holistic approach designed to enable procurement of bridges with the maximal possible sustainability (life-cycle advantages) under D-B contracts. The approach combines LCC Added-Value analysis with other techniques that make bridges’ aesthetic merit and environmental impact commensurable using an adapted concept named the willingness-to-pay-extra (WTPE).The systematic analytical procedures and potential of LCCA to deliver major savings highlighted in this thesis clearly demonstrate both the feasibility and need to integrate LCCA into bridge procurement and management decisions. This need has been recognized by Trafikverket (the Swedish Transport Administration), which has implemented a software tool developed in the research (BaTMan-LCC) in its bridge and tunnel management system (BaTMan). This thesis introduces readers to the field, considers BaTMan and the bridge stock in Sweden, discusses the developments outlined above and obstacles hindering further implementation of LCCA, then presents proposals for further advances.