Abstract for: System Dynamics for Ageing Bridges

In the Netherlands, a substantial share of the bridge population was constructed between 1950 and 1980. These so-called ‘baby-boomer’ bridges are reaching the end of their service life in the coming decades. Without timely intervention, structural failures will increase, causing substantial traffic disruptions We developed an object-oriented System Dynamics model in Ventity to evaluate the effects of the current strategy and alternative strategies under uncertainty. The object-oriented approach made the modelling of age cohorts feasible We found that pursuing the current strategy will result in substantial traffic hindrance in the long term. A productivity increase in replacement projects was found to be absolutely crucial in tackling the ageing challenge, while other strategic options, such as automated monitoring and inspection, showed little effect. Our main contribution was strategic decision support: which strategies are worth diving into, and which can be discarded from future analysis? Such insights prevent a substantial amount of resources (money, personnel, time) from being wasted on the operationalisation of ineffective strategies. Other lessons learned were that ‘numbers’ better convey the urgency of the situation than qualitative narratives, and that a transparent line of reasoning behind quantitative results is crucial in policy settings.