# Where Are Smart Cities Heading? A Meta-Review and Guidelines for Future Research
## 3 Results
### Smart Cities Dimensions  
There is no consensus in the literature on the dimensions of smart cities. However, there is some degree of agreement in the selected dimensions (Figure 3). [PERSON] and [PERSON] [27] identified six dimensions, namely \"smart economy\", \"smart governance\", \"smart living\", \"smart mobility\", \"smart people\" and \"smart environment\", while [PERSON] et al. [29] identified three main dimensions, \"technology\", \"community\" and \"governance\". Grouping the dimensions identified by [PERSON] and [PERSON] [27] and by [PERSON] et al. [29], we place special emphasis on (1) \"community\", which includes smart life, smart mobility and smart people, and (2) \"governance\" where we focus on smart governance and smart environment. As far as technology is concerned, we frame it as being directly related to digital transformation, which is one of the macro topics analyzed in the article. This section follows a top-down approach to the conceptual framework, starting with a discussion of the \"community\" dimension (Figure 3). In the literature, it is evident that \"social infrastructures\" (topic III) of smart cities have a strong relationship with human and social capital. Human capital (i.e., skills and proficiencies of a person or group) and social capital (i.e., number and quality of relationships that connect social organizations) are critical, as they foster innovation. In this regard, universities stood out in the literature, as they are organizations formed by highly qualified people (i.e., \"intelligent people\"). Intelligent people usually stimulate human capital, and tend to develop disruptive technologies, transferring them to public and private organizations. E-participation and e-government are good examples, as they are based on the latest technologies, such as AI. These technologies have improved the participation of citizens in general, as they make cities more efficient in terms of decision making by policymakers and government service delivery. The \"smart environment\", in addition to being part of the community dimension (topic I), is also directly related to the \"sustainability\" of smart cities (topic III). This dimension includes a series of waste management strategies, pollution control, etc. That is, the use of technology assists in the preservation of natural resources through sustainable methods and real-time data collection. These methods are helping decision makers to optimize the classification, collection, recycling and reuse of waste. The Organization for Economic Co-operation and  
Figure 3: Conceptual framework. Development (OECD) considers the development and preservation of natural, economic and human capital to be essential elements for \"smart living\". All factors that make contemporary human life possible, such as social well-being and associated technologies, can be included in this sub-dimension. \"Smart living\" is also broad, as it spans from using smart home applications (e.g., home automation) to the workplace (e.g., grid-connected and internet-enabled lighting and security). These applications may also collect personal and private data about their users, incurring privacy and security risks. Lastly, \"smart mobility\" is often focused on transport systems and infrastructure, as frequent problems in cities are related to congestion, queues and delays. In this sub-dimension, the widespread use of connectivity (e.g., IoT) has been key. It provides real-time data to determine the best routes, allowing traffic efficiency and greater security. Regarding \"governance\", it can be subdivided into two relevant issues (Figure 3). The \"smart economy\" comprises the guidelines and policies that inspire innovation and creativity. Innovation is associated with scientific research and disruptive technologies, with special attention given to sustainability (topic III). In general, the smart economy makes use of information and communication technologies (ICT) to improve the economic element of a community and the socially responsible use of resources.