# IoT-Enabled Smart Sustainable Cities: Challenges and Approaches
## 4 Smart and Sustainable Urban Mobility  
As stated in Section 3.2, mobility is one of the pillars in the design of smart city services, and can significantly improve indicators for municipalities and stakeholders. In the following, a focus on smart mobility solutions and technologies is provided. It is well known that _near-to-zero_ emissions and reduced traffic jams, in conjunction with the adoption of smart transportation approaches and IoT-oriented paradigms, will produce relevant impacts on the quality of life and the environment in smart cities, thus increasing virtuous habits among the citizens [101]. Therefore, the way mobility and transport aspects will be handled in smart cities is highly supported by the adoption of Intelligent Transportation Systems (ITSs), capable of managing traffic-related aspects (such as smart parking, car sharing [102], speed control systems, etc. ), which will be fundamental in the future. To this end, the introduction of IoT-related concepts in conjunction with ITSs will certainly impact mobility and transport applications [103, 104]. This trend will dramatically change the way city operators and people living the city itself will interact with its nearby infrastructure: how citizens live and move in the city (e.g., roads, streets, cycle paths, public transport stations, private and public parking spaces, etc. ), how the city entities (e.g., mobility operators and transport units) plan their activities and configure the transportation infrastructure--through the concept of Vehicular Area Networks (VANETs) [105, 106]--and how these planning activities are managed and performed [107]. This further highlights the fact that several trends are changing the landscape of modern cities, as life becomes more connected and augmented by the technology, modern urban economies require a fast Internet connectivity (and scalable IoT-based solutions), and citizens need fast, accessible, and on-demand forms of transportation [108]. In general, a complete infrastructure willing to integrate the sustainable mobility concept with IoT-oriented paradigms, has to be able to perform several tasks, as shown in Figure 11, with particular focus on the data resulting from these mobility-related scenarios, as follows. * Support both _local_ and isolated scenarios (not connected to the Internet), and _fully on-Cloud_ architectures, in order to continuously collect a large amount of heterogeneous data from the city infrastructure [109], supporting several paradigms for data injection (e.g., on-demand data, proactive forward, scheduled forward, etc.) [110, 111]. * Handle safety-critical scenarios, where involved entities (both IoT-related and not) should interact with the municipality's control centers (e.g., traffic congestion area, pedestrian crossing paths, event mass moving) in a safe and secure way, even providing mechanisms to cope with the lack of connection/communication [112]. * Guarantee proper data management, according to data protections regulations [113] (e.g., the General Data Protection Regulation, GDPR [114]) and with respect of their ownership and protecting the involved entities [115]--as discussed in Section 3.9--against possible data threats (e.g., external intrusions, data tampering, Man-in-the-Middle (MITM) attacks, data sniffing, etc. ), informing law enforcement agencies in case of data breaches [91, 116];
* Provide distributed storage mechanisms, in order to decentralize the mobility network (and avoid bottlenecks often affecting centralized solutions), thus supporting efficient strategies for data retrieval and disaster recovery. * Provide high-layer mechanisms for the execution of AI and other data analysis algorithms, in order to extract features and implement predictive mechanisms based on the collected environmental data (e.g., smart parking, predictions on traffic flow, and traffic flow reconstruction) [117, 118].