Users' vulnerability and exposure in Public Open Spaces (squares): A novel way for accounting them in multi-risk scenarios

Public Open Spaces (POSs) such as streets and squares, in our cities are characterized by spatio-temporal variations of users' vulnerability and exposure in view of the hosted social, governmental, religious, and commercial functions. Single or multi-risks conditions in POSs can hence vary over time. This work proposes a methodology to perform local-scale analyses on use patterns in real-world POSs, pursuing a quick-to-apply approach based on remote analysis tools and easy-to-apply surveys, to be also used by non-expert technicians. Main literature-based factors concerning users' vulnerability/exposure and methods for their collection are identified. Rules to define typological (that is recurring) scenarios are provided through specific key performance indicators relating to overall POS use and daily/hourly temporalities. The methodology capabilities are preliminary assessed through a sample of 56 squares in historic Italian cities, considering working days and holidays. Results trace the overall typological characterization of the squares sample adopting a “robust-to-outliers” approach, and provide bases for expeditious assessment of users' vulnerability and exposure scenarios. The typological scenarios can be then used to support rapid risk assessment actions in POSs by safety designers and local authority technicians, and employed as input in simulation-based analyses to include the users' features in the related evaluations.