Introduction
Future cities are based on maximum physical activity and mobility, social interaction, vitality and environmentally friendly modes of transportation. In this regard, it emphasizes safe, affordable, accessible and sustainable modes of transportation. In fact, they encourage a healthier and more active lifestyle that encourages aspects of social communication and reduces environmental issues. At the same time, they impose maximum restrictions on the expansion of cars, fossil fuel consumption and air pollution in cities. Future cities give the main priority to pedestrianization in the field of transportation and, in fact, have introduced pedestrianization as an alternative mode of transportation. In fact, the city of the future encourages walking or is a driver of walking. Hence, the model of walkable cities can respond well to these goals. Because this mode of transport helps to reduce the number of personal vehicles, it helps to reduce traffic congestion and reduces pollutant emissions, and consequently, promotes sustainability by reducing environmental degradation. Walking is the most democratic mode of urban transport, as it ensures access to basic services for pedestrians and a higher quality of use of these services. In addition, pedestrian-friendly public spaces promote physical activity, social interactions, and recreational activities. On this basis, the present study focuses on developing a conceptual framework for the feasibility of a walkable city as a model of the future city.
 
Theoretical framework
The term walkability refers to an urban space that is conducive to walking behavior. By this definition, a walkable place is a place where you can walk safely, comfortably, and pleasantly. Walkability measures the quality of walking conditions, including the presence of walking facilities and the degree of safety, comfort, and convenience of walking. Several factors influence the walkability of a street, neighborhood, or city, from the physical functionality of a place to the perception of the individual walking. In other words, the factors that define a space as walkable are not limited to the physical dimensions of a place, but also include perception. This requires a multidimensional approach to analyzing walkability.
Methodology
The present study is classified as a developmental research in terms of its purpose. In terms of its method, it is classified as a qualitative research based on the meta-synthesis method. The reason for using the meta-synthesis method in the present study is that there is no precise and clear explanation of the conceptual model of the feasibility of the walkable city. The statistical population includes all the resources published in the period from 2015 to 2024 regarding the walkable city. The research resources were selected using purposive sampling. The meta-synthesis method based on the seven-step method of Sandelowski and Barso (2007) was used to extract and analyze the research data. The statistical population consists of 210 sources related to the walkable city, which were screened based on purposive sampling. Initially, 210 sources on the topic of walkable cities were identified from reputable scientific databases, of which 86 were excluded in the initial evaluation and review. Therefore, in the next step, 124 sources were screened. After reviewing and evaluating them, 61 sources were excluded from the research process in terms of the relevance of the title to the research objective, accessibility, relevance of their abstract and content, and also evaluating their methodology. As a result, 63 sources were deemed eligible for the full-text study. Of these, 42 sources were ultimately selected for the final analysis of the research. The aforementioned sources were extracted from reputable scientific databases such as Sage, ResearchGate, Elsevier, MDPA, Emerald, and Taylor & Francis.
Result and discussion
The results of the study indicate that the walkable city has 6 selective codes and 34 core codes consisting of environmental, social, health conditions, macro, medium, micro scale, comfort components, security, connectivity and accessibility, simplicity, directness, traffic safety, attractiveness, aesthetics, transportation integration, physical environment, visibility, comfort, pleasantness, diversity; vehicle restrictions, shops and services, social activity, area, edges and facades, street beauty, green space; planning scale, street scale, detailed scale; health and recreation, energy and environment, economic development, social development. The extracted coefficient of the Kappa index is 0.86 with a significance coefficient of 0.000, confirming the reliability and quality control of the results of the present study. As a result, the conceptual framework for the realization of a walkable city consists of contextual conditions, scale, key components, walkable environment design, strategies, and consequences.
Conclusion
The concept of pedestrianization has developed in three distinct phases, consisting of the pre-industrial era, the era of the advent of automobiles and the subsequent subordination of the urban environment to mechanization and the neglect of pedestrians, and the era of correcting the disadvantages of mechanization in cities. Studies related to the walkable city are divided into two main groups: macroscale and microscale. Pedestrianization at the macroscale focuses on the physical environment at the city or neighborhood scale and its impact on pedestrian behavior. In this regard, concepts such as density, diversity, design, connected environment, pleasant, visible, comfort, convenient, coexistence, and committed are emphasized. Macroscale studies mainly focus on environmental factors, topography, residential density and land use diversity, street connectivity, and how these macroelements affect walking in cities. On the other hand, pedestrian studies at the microlevel have paid more attention to the microelements of the physical environment, such as the continuity and width of sidewalks, the presence of green elements, pedestrian crossings, etc. at the street scale. Micro-level studies include environmental and physical design features that sometimes require qualitative measurements. In addition, urban pedestrian studies have experienced three major developments: the first period focused on the physical conditions of walkable places, which aimed to define a walkable city and its main components. The second period focused on pedestrians’ perceptions and thoughts about their surroundings. The third period focused on the physical and perceptual dimensions of walkable cities.