Integrating thermal comfort into traffic calming objectives: a proposal for a street redesign strategy in the face of rising summer temperatures

Urban areas are particularly vulnerable to the effects of climate change, and they are experiencing increasingly frequent and intense extreme events, such as summer hot waves. The work focuses on the relationship between this phenomenon and the use of public spaces, with particular attention to urban streets. In order to allow suitable conditions for the use of such spaces, design strategies should address multiple issues such as safety and social functions, as well as thermal comfort. The thesis aims at studying an integrated approach of street design combining the goals of traffic calming strategies and thermal comfort solutions, and testing this strategy on a case study in the city of Turin. The theoretical framework is composed by four parts. The first part describes the role and functions of urban streets. An overview of the evolution of street design is proposed, from the approach characterising the second half of the last century, to the models aiming at an integration between the functions of “link” and “place”. The second part of the theoretical framework focuses on the concept of traffic calming, as a tool to improve safety, allowing a better coexistence of social functions with mobility needs, with a focus on the Italian approach. The third part provides a definition and the main characteristics of urban microclimate, and the relationships with climate change. The section illustrates the concept of thermal comfort and the tools described by the literature to improve this condition for the users of urban spaces. The last part aims at finding a synergy between traffic calming strategies and thermal comfort solutions. An approach aiming at combining the goals of the two components is defined, by stressing its potential benefits and its limitations. The project component of the work proposes a scheme for redesigning a few streets, aiming at improving safety and at increasing the provision of space for multiple social and mobility functions. In the definition of the design strategies, the concept of thermal comfort is central, in order to favour the use of space in a context of rising temperatures. The application and the evaluation of the measures aiming at this objective are supported by the use of simulations conducted through the software “ENVI-met”, with the analysis of a series of parameters affecting the conditions for a pedestrian using the space. Therefore, a first simulation was performed with the goal of analysing the perception of thermal comfort in the current state. The interpretation of its results highlighted the main critical elements and needs in terms of thermal comfort, in order to guide the design strategies with the goal of a synergy with the component of traffic calming. The project consisted in the elaboration of scenarios of transformation, integrating the multiple functions of the street with different degrees of priority, by applying in all cases solutions for the improvement of thermal comfort. The integration of the constraints related to different components, especially linked with dimensioning requirements according to the norms in force, highlighted the synergies and conflictual elements between the uses of space, and the necessity for trade-offs in the determination of a solution. Finally, the scenario allowing a maximisation of the needs for thermal comfort was selected for a second simulation, aimed at evaluating the effectiveness of the strategies adopted.