Economics of geotechnical asset deterioration, maintenance and renewal

Transport and other infrastructure systems are supported on, adjacent to and retained by extensive systems of earthworks of varying (and increasing) age, and of variable original construction quality. These earthworks are subject to natural deterioration, which can be accelerated and complicated by the effects of climate change. The ACHILLES research program is providing improved understanding of earthworks behavior, performance and deterioration. It is also developing methods and tools to analyze and provide decision support for the construction, maintenance and renewal of earthworks, with particular emphasis on the management of existing, deteriorating assets. The work described here aims to identify the most cost-effective timing and means of extending earthworks asset lives and maintaining their safety and serviceability. Conventional cost-benefit analysis methods, of the type used for new infrastructure projects, do not directly provide the decision support needed for the maintenance and renewal of existing earthworks assets. An alternative approach is proposed and applied to a modeled example, demonstrating the potential asset management benefits of early, pre-emptive intervention, the economic attraction of deferred intervention, and the means of identifying an intermediate whole-life cost ‘sweet spot’, based on a timely assessment of intervention options. The handling of the uncertainty associated with earthworks behavior, deterioration rates and times to failure is also considered, as is the extension of the single-asset approach to the management of multiple earthworks assets.