The fourth pillar of infrastructure sustainability: Tailoring civil infrastructure to social context

This research proposes technical performance over time as a fourth pillar of sustainability theory for infrastructure. It also describes a method that allows us to discover how changes in the technical pillar (operationalized as reduced breakage rates) may moderate the influence of the social pillar (operationalized as repair rates) on sanitation infrastructure outcomes. Oral histories were used to develop a history of sanitation for each of 152 poor households in four rural communities in Bangladesh that have gained access to sanitation in the past decade. Transcriptions and qualitative coding identified reported states of sanitation (for example, broken vs. functional) at three time steps. These were used to develop an initial vector and transition matrix for a Markov chain analysis. The breakage rate in this model was then adjusted to investigate the impact of improved technical durability on sanitation outcomes. For the case analysed here, we found that increasing infrastructure durability by 50% (an estimated increase of two years) increased the rate of functional sanitation system use at model convergence from 54% to 88%. Increases in durability also caused households to use private rather than shared systems. Beyond this specific case, the generalizable theory and method presented here are analytic tools that permit targeted technical accommodation of social contexts specific to individual project sites.