# Mobility, Citizens, Innovation and Technology in Digital and Smart Cities
## 3 Cities Transportation Trends
### Mobility and Citizens  
A technology becomes part of society when those who use it do not realize its presence, such as concepts surrounding ubiquitous computing [61]. Some authors discussed the growing possibilities of pervasive Artificial Intelligence [62] in SC [63]. A similar idea applies to rules/laws/policies; for example, smoking inside closed places is no longer an issue noticed or missed. For instance, Figure 3 shows a driverless bus running in the technology center in _La Defense_, Paris. In the future, citizens may not even notice the amount of technology embedded into cities' transports. Thus, technology can even be part of the cities without a daily perception about it. Figure 2: The rise of the interest in SCs’ transportation systems by different field of knowledge (search was done on June 20 th, 2019 on the Scopus database). If one considers the current possibilities that the decentralized transportation systems are promoting, we may notice an omnipresent interaction with citizens' interests. As an example, the actual route that a private car can take (like when you call an Uber) can be chosen according to clients' desire. This example reinforces the ability that Information and Communication Technologies (ICT) has with end-users, providing the option of choosing the most suitable transportation system that fits personal beliefs [64]. Interacting with citizens in order to guide their way of moving around is becoming a reality for those which are living in modern urban cities [65; 66]. The constant interaction by means of online services proportionate the opportunity of picking different routes for reaching a destination considering real-time measured data. In this sense, different maps' services provide possible routes that use different types of transportation and forecast the arrival in the final destination within an expected time limit, considering stochastic information about traffic. Improving the interaction between citizens and public/private transportation systems represents a challenging issue. The main core of this problem relates to the design of systems that interact in a transparent, fast and reliable platform. Blockchain based technologies can be used for promoting transparency [67] and also reducing costs [68] (as will be emphasized in Section 3.5), while the other aspects related to data sharing may come consequently from other advocated points of the SC concepts. On the other hand, we highlight the importance that urban policies have in order to regulate old transportation systems, such as noisy vehicles and pollutants' emissions, even considering the fact that electric based transportation systems are not more sustainable than fuel based ones since the problem turns to where energy is really being produced. Inside cities, it is quite obvious that less pollution will be emitted by those electric systems; thus, it is a consensus that urban environments will become more pleasurable. Regarding this aforementioned reasoning about where energy is really produced, it is noteworthy that Smart grids [69; 70], in particular, microgrid systems [71], will play the role of decentralizing energy production. In addition, citizens are another key point that will become part of these smart systems, since energy consumers are also becoming suppliers [72; 73; 74]. Bike sharing comes to cover some of the cities' public transportation failures and has become a common means of transport in urban centers [75]. An efficient shared bicycle system includes stations in areas of greater demand, pondering a trade-off between cost and benefits of each station. A combinatorial optimization problem of placing such stations along the cities is crucial [76], being advocated as a crucial tool for helping urban managers. Other optimization problems were dealt in order to determine the optimal number of bikes in each station [77], most of them handling stochastic variables and modeling. Other works in the literature dealt with the simulation of such scenarios [78].