A Digital Twin Simulation Framework to Assess the Impact of Street Experiments: Transforming Urban Mobility in Acireale (Italy)

Urban mobility policies focus on several strategies and actions towards sustainability, among them the implementation of street experiments schemes to discourage high-polluting vehicles entering in urban areas. The increase in vehicular traffic generates numerous externalities, including high congestion levels, polluting emissions and a worsening of the quality of life, especially in urban centers. To reduce these critical issues, one can refer to experimental Low Speed Zones (LSZs) or Limited Traffic Zones (ZTLs). These vehicular traffic restrictions can be of several types: spatial (i.e. territorial extension), permanent or temporary (i.e. variation in duration over time); partial or total (i.e. reserved only for specific categories of vehicles). This work presents a methodology to evaluate the impact of traffic restriction configurations through a digital twin implementation based on microsimulation models to perform scenario analyzes and evaluate quantitative variables (e.g. service levels, queue lengths, delay times). Different scenarios have been simulated and assessed within the municipality of Acireale (Italy): (i) permanent ZTL with limited extension to the central area of the historic centre; (ii) temporary restricted traffic zone extended to the entire historic center; (iii) permanent ZTL extended to the entire historic center (assuming a modal shift in travel demand); (iv) 30 km zone extended to the entire historic centre. The obtained results, associated with the northern area of the city at the entrance to the historic centre, show that the spatial extension and temporal duration of these street experiments can generate critical issues on alternative roads. Future research developments will include the integration of emission models to assess the environmental impacts deriving from the proposed sustainable mobility actions.