Reshaping urban streets for the 21st century challenges: Environmental direction

Smart mobility, a main component of smart city development, represents an intelligent transport and mobility network, that integrates advanced technological and mobility solutions. The Street21 research project takes up these challenges and addresses the complexities by exploring and analysing innovative strategies to redesign urban at-grade intersections in the framework of new mobility challenges. One of the objectives of the project is the effective use of the traffic simulation tool VISSIM to model complex traffic flow behavior under specific roadway and geometric conditions at 5 signalized intersections in Thessaloniki city. The simulation model successfully captures heterogeneous traffic conditions and supports the assessment of traffic operations under the existing roadway and geometric set up. Moreover, emissions estimation for CO, CO2, NOx, PM10 and PM2.5 were performed using the integrated emission algorithm. The results reveal that emission rates for all pollutants are significantly elevated at low vehicle speeds, particularly below 10km/h. These elevated emissions correspond to areas near signalized junctions, where driving behavior is heavily influenced by stop-and-go patterns, including idling, frequent acceleration and braking cycles. Such driving patterns lead to inefficient combustion and higher pollutant output. The calibrated simulation model, combined with emissions estimation, is a powerful tool for understanding the environmental impact of urban traffic and supports informed decision-making in sustainable transportation planning.