In this section, two main domains of “Walkability indices”, and “ICT and its impact on walkability” have been reviewed; concluded by the authors’ insights on the literature review.
2.1. Walkability Indices
Over time, various methods have been proposed to identify a walkable neighborhood. The study of Frank et al. (2010) is as one of the first studies that tried to quantify walkability in cities and provide physical indices. Their criteria include land-use mix, street connectivity, net residential density, and retail Floor Area Ratio (FAR) and among them, the street connectivity is doubly important. Following this trend, many research projects during the last two decades tried to introduce the best and most accurate indices. Some studies examined walkability indices regarding trip types, as some experts believe that there is a relationship between the effectiveness of these indices and the purpose of the trip. Another set of indices examine the behaviour of pedestrians based on the importance and desirability of trip destinations; for example, daily destinations such as pharmacies or grocery stores have a greater impact on walkability than nightclubs and sports facilities (Manaugh and El-Geneidy 2011). A group of experts believes that the urban form has the greatest impact on the walking rate of residents (Lefebvre-Ropars et al. 2017) and it includes Density, Diversity, Design, Destination access, and Distance to transport stations (5Ds) (Ewing and Cervero 2010). This view is also emphasized in the study of Barros et al. (2017) in Lisbon, Portugal from the perspective of space syntax criteria. Another group of scientists introduced the classification of walkability criteria in the form of 7C’s (Ruiz-Padillo et al. 2018).
Although most studies about walkability indices are done in the United States, Canada, Australia, China, and Belgium (Tong et al. 2016; Wang and Yang 2019), there is no complete and standard version of universal indices for all locations and times, and depending on the features of case study, research objectives and details of the study, a set of different indices should be used (Manaugh and El-Geneidy 2011; Wang and Yang 2019). For example, in a study of walkability factors in developing countries, Talaei and Taheri Amiri (2017) added greenness levels, shade, and visibility to urban landmarks to Frank's early indices. Numerous studies in South America showed that public security and traffic safety are particularly important in South America and should be added to walkability measurement metrics in these countries. Urban crime influences other physical and environmental aspects of walkability, therefore, public security is the most important index of walkability in Brazil, and traffic safety is in the second place (Ruiz-Padillo et al. 2018). Similarly, Bailey-Catalán et al. (2019) in their study of the city of Valparaiso in Chile, examined the NEWS-A index and emphasized the importance of social factors such as fear of crime in South American cities. A third study in Latin America, after a ten-year review of the impact of artificial environment on walkability in a moderate city, concludes that for providing a walkable environment, traffic safety and security in South America are more important indices than the physical conditions of sidewalks and their attractiveness (Arellana et al. 2020). Recent studies attempted to complement existing indices with context-specific factors. For example, the question may arise about the factors that affect walkability in immigrant-friendly and multinational cities. Battista and Manaugh (2018) in their study in Quebec, Canada claim that apart from environmental factors, multicultural and social policies have a great impact on walking in the neighborhood and these indices should also be considered as important. While the European cities are generally more walkable than North American cities (Bödeker et al. 2018), another study in Norway (2019) based on the urban context in the country of case study, considers indices such as ‘infrastructure and traffic, urban planning and environment, and activities’ as a set of main indices to assess the level of walkability (Knapskog et al. 2019).
Over time, viewpoints on walkability grew more specialized, and its measurement parameters fluctuate in a range of small to large-scale, quantitative to qualitative (Talen and Koschinsky 2013), and leisure trips to business trips (Manaugh and El-Geneidy 2011). However, walkability studies overlook an important fact that, people's perceptions of neighborhood walkability may not always be in line with measurements results (Talen and Koschinsky 2013). For example, the Walk-Score index sparked a lot of controversy over the accuracy of scoring in American cities. The important point is that the score given to walkability in each neighborhood varies depending on the definition and how the indices are calculated. Therefore, walkability indices cannot be used comprehensively in all cities, but depending on the context, researchers need to select the best indices of pedestrians’ behavioral and social aspects. Another point is that walkability indices change over time, depending on the definition of walkability. For example, if we define walkability from the viewpoint of people's health, the impacts of environmental factors on it are more important than when we consider it as a mode of transportation. In the secondary viewpoint, accessibility factors become more important. Even the concepts and formulas for measuring indices vary depending on the researcher's definition of walkability (Shashank and Schuurman 2019).
2.2. ICT and Its Impact on Walkability
ICT services change the relationships between humans and their living environment while affecting social and economic development (Dadashpoor and Yousefi 2018). ICT may affect walkability in two general ways: first; technology as a problem that reduces walkability by transferring functions to the virtual world, and second; technology as a solution; a tool for strengthening walkability (Hankel et al. 2018). Due to the overlap among urban elements such as density, mixed land-use, access and transportation network, urban layout (how to connect urban spaces to each other) and housing characteristics, understanding the impacts of ICT on the spatial structure of cities will only be possible by considering all elements of this structure (Dempsey et al. 2010). In the following paragraphs, we have reviewed the impacts of ICT on various urban aspects that affect the walkability of neighborhoods.
ICT’s impact on urban public spaces: Increasing use of communication technologies reduced activity in public spaces and affected the way people interact with each other, and with physical spaces around them. Thus, public spaces are neglected and their attractiveness decreases resulting in declined social life. Social interactions through telecommunications on social media reduce the number of citizens' activities in the physical spaces (Abdel-Aziz et al. 2016). However, the real experience is irreplaceable, and the use of ICT devices (smartphones, computers, etc.) leads to the flexibility of urban nodes. In other words, citizens continue to use urban nodes, but their usage changes to leisure activities (Wang et al. 2015).
Information Technology (IT) affects the mental image of citizens and adds new dimensions to the legibility of the urban spaces (Al-ghamdi and Al-Harigi 2015). Digital tools allow their users to customize the urban spaces to their liking by applying software settings and in this way, they strengthen the sense of place. Urban designers should be able to use the potential of technological tools to enhance interactions in public spaces at the same time of following the principles of good design (Abdel-Aziz et al. 2016). Technology is capable of interacting with users of urban spaces, improving the quality of life and sustainability, and creating a sense of belonging by supporting neighborhoods’ independence (Al-Thani et al. 2018).
ICT can change face-to-face relationships or complement them by virtual communications (Konrad and Wittowsky 2018). Additionally, ICT allows people to develop their social relationships. Some researchers believe ICT caused virtual communication to replace face-to-face ones. Others believe reversed. While the third group thinks that substitutions and incremental effects of ICT on human communications neutralize each other and there is no significant relationship between ICT and face-to-face communications. Variety of Internet-based entertainments (computer games, virtual tourism, leisure in the virtual world, etc.) reduces people's activity in other types of leisure (Yousefi and Dadashpoor 2020) and the e-city reduces the presence of people in city centres by changing cultural and recreational spaces -from real to virtual spaces- (Ahani and Pourmohammadi 2019). After the transformation of IT into ICT, social networks were created with the ability to maintain social relations without the need for geographical proximity (Ben-Elia and Zhen 2018), and people socialize through cyberspace, instead of meeting each other in public spaces (Abdel-Aziz et al. 2016). Overall, ICT adds digital spaces to open spaces, and both of them compete for social interactions (Djukic et al. 2019). New communications opportunities and virtual communication media allow citizens to make better use of public spaces by saving their time (Abdel-Aziz et al. 2016). Despite the emergence and development of the IT network, face-to-face interactions in quality public spaces will not lose significance. Although modern societies do not depend on walking to provide their basic needs, they need suitable public spaces to ensure their mental and social health (Lehmann 2016). Cyberspace is effective in shaping real space and has made the concept of space more complex by overcoming temporal and spatial constraints.
ICT’s impact on urban land uses: ICT has changed traditional urban functions (work, transportation, housing, and leisure) (Yousefi and Dadashpoor 2020). E-city components have direct impacts on urban land use which can be an increase or decrease in the required spaces or decentralization from the city centre (Ahani and Pourmohammadi 2019). While ICT outspreads, existing urban land-uses are replaced by those with new features and significant changes occur in the performance of urban spaces (Yin et al. 2011). New features of urban land-uses are more visible in central and dense areas accommodating short trips (de Abreu e Silva and Melo 2018). E-city reduces the need for office and commercial spaces and disperses them from the city centre (Ahani and Pourmohammadi 2019).
Telecommuting increases the compatibility of urban land-uses and provides the opportunity to develop urban areas with mixed land-use (Wang et al. 2015).
ICT’s impact on urban mobility: ICT affects transportation infrastructures and people's travel behaviour (Snellen and De Hollander 2017). It increases the use of public transport since citizens are aware of the advantage that they can do other things during their commute (Konrad and Wittowsky 2018). The impacts of ICT on travel have been discussed since 1980 (PC Lila and MVLR Anjaneyulu 2016) and four modes of switching, amplifying, modifying, and neutralizing are considered to explain the quantitative impacts of ICT on transportation (Konrad and Wittowsky 2018).
The relationships between ICT, access, and mobility are complex (Vale et al. 2016). Today, with the extensive use of the internet, the concept of access has changed (a new concept has emerged as virtual access) and accessibility cannot be measured by calculating the time, distance, and cost of trip (Yousefi and Dadashpoor 2020). ICT provides a range of trip patterns (Jamal et al. 2017). The results of previous studies show that online shopping does not necessarily reduce shopping-related movements as it complements traditional shopping and traditional shopping is associated with other activities (Yousefi and Dadashpoor 2020). Also, digital marketing introduces new retailers to citizens who are used to searching for information, and frequent shopping (Jamal et al. 2017).
ICT provides new opportunities for travel planning (Konrad and Wittowsky 2018). The use of ICT in the public transportation system will improve the quality of public transportation services and will increase its users (Feikie et al. 2017). Even, telecommuting is not an effective strategy for managing travel demand and may lead to a higher rate of car ownership (de Abreu e Silva and Melo 2018). Promoting ICT along with the development of walking, cycling, and bicycle parking softwares and applications provides more opportunities for transportation and communications, and reduces unnecessary uses of private vehicles (Feikie et al. 2017; Jamal et al. 2017).
It can be inferred from reviewing the literature that walkability indices during these two decades of studies have moved from major urban subjects such as mixed land use, network connectivity, and population density toward minor subjects like the width of sidewalk, and psychological subjects such as experienced safety and attractiveness. Walkability is dynamic and changes under the influence of some factors, including technology. ICT affects different elements of urban life and in this way, it changes the quality of urban design. ICT applications in urban life affect walkability, but how it changes is not clear since we face many uncertainties about the future of walkability in neighborhoods. Considering the difficulty of predicting the future and the existence of numerous uncertainties, applying the futures study, that tries to discover different futures instead of predicting a single future, increases the probability of achieving the preferred future.
 Connectivity, Convenience, Comfort, Conviviality, Conspicuousness, Coexistence and Commitment.
 The Neighbourhood Environment Walkability Scale (NEWS), a 68-item questionnaire, is the most commonly used method to evaluate walkability. Later, Cerin et al. (2006) developed a simplified version of NEWS (NEWS-A). The NEWS methods consider the following environmental characteristics: (a) residential density; (b) proximity to non-residential land uses; (c) ease of access to non-residential uses (land use mix-access); (d) street connectivity; (e) walking/cycling facilities; (f) aesthetics; (g) pedestrian traffic safety and (h) crime safety. Liao et al. (2020)