A city has money to either strengthen a bridge or build a new community shelter. How would experts decide which one to do first, based on avoiding the most harm for the cost?

Experts would decide which project to prioritize, strengthening a bridge or building a new community shelter, by employing a structured decision-making process centered on risk assessment and cost-benefit analysis or cost-effectiveness analysis, aiming to avoid the most significant harm for the resources invested. This process begins with a comprehensive risk assessment for each scenario. For the bridge, experts would evaluate the probability of its failure—how likely it is to collapse or become unsafe—and the potential impact of such an event. Impact includes direct consequences like loss of life, injuries, property damage, economic disruption from traffic diversion or trade interruption, and the cost of emergency response and long-term repairs. For the community shelter, the risk assessment would consider the probability of unmet needs for vulnerable populations worsening—how likely it is that individuals will face homelessness, exposure to elements, lack of safety, or inability to access essential services without a new shelter—and the potential impact of these conditions. Impact here includes increased health crises, social instability, reduced quality of life, potential fatalities due to exposure, and increased strain on emergency services and healthcare systems. Once risks are quantified for both projects, experts proceed with cost analysis, detailing the total financial outlay required for strengthening the bridge and for constructing the new shelter. This includes planning, materials, labor, and potential long-term maintenance costs. The core of the decision lies in cost-benefit analysis (CBA), where the monetary value of the avoided harm (the benefit) is directly compared against the cost of the intervention. Experts attempt to monetize harm, assigning a financial value to adverse outcomes such as lives saved, injuries prevented, economic productivity maintained, and societal well-being improved. For example, the economic value of a prevented fatality, the cost savings from reducing homelessness-related healthcare burdens, or the economic output preserved by a functional bridge are calculated. Where direct monetization is challenging, cost-effectiveness analysis (CEA) is used, comparing the cost of achieving a specific positive outcome (e.g., cost per life saved, cost per person adequately housed). This approach allows a comparison of how much each dollar spent contributes to reducing specific types of harm. Additionally, experts consider multi-criteria decision analysis (MCDA), which incorporates non-monetary factors like ethical considerations, social equity, community resilience, and legal obligations, weighting them alongside monetary values to provide a holistic view. For instance, legal requirements might mandate a certain safety standard for infrastructure, while ethical frameworks emphasize the right to shelter. The ultimate goal is to identify which investment—strengthening the bridge or building the shelter—yields the highest ratio of avoided harm (benefits) to its cost, considering both immediate and long-term consequences, thereby ensuring the city's limited funds are allocated to prevent the most significant and wide-ranging negative outcomes.