ReACT addresses the issue of assessing and mitigating single and multiple risks in built metropolitan and urban environments (MUBE), considering the interaction between physical elements and users, thanks to a holistic approach for defining, simulating, and analyzing single and combined scenarios with slow-onset (e.g., heat waves) and sudden-onset (e.g., earthquakes and floods) disasters. ReACT aims to:

1. systematize a spatiotemporal approach to single risk and multi-risk assessment, incorporating inclusive human factor dynamics in terms of exposure (how many users), vulnerability (with which characteristics), and behavior (how people respond);

2. improve knowledge on scenario modeling, even for non-critical ones, through storylines and "what-if" approaches that also consider the impact of secondary elements of MUBE;

3. adapt and expand existing rapid assessment methods and behavioral simulation tools, taking such aspects into account;

4. define multi-criteria evaluation logic for single/multiple risks, focused on the scale of outdoor public spaces and their aggregation, supporting decision-makers in the pre- and post-retrofit analysis of the MUBE;

5. support communication, engagement, and training of stakeholders and citizens through VR/AR