# Mobility, Citizens, Innovation and Technology in Digital and Smart Cities
## 3 Cities Transportation Trends
### Blockchain for Managing Cities' Transportation Data and Contracts
#### 3.5.2 Removing the Trust Barrier  
As aforementioned, blockchain inspired technologies have been emerging as a mechanism for promoting transparency and reducing costs through the distribution of responsibilities and resources to manage an informational network. The advance in the use of personal data to foster business strategies has been gaining attention for a couple of years [175] because of trade-offs between private profitability, social well-being and public awareness about individual life data. Although users' motion data have been important to offer novel transportation options, the way we interact with this data and reach agreements still requires third parties. Turning the latter into a transparent layer is one of the main possibilities of DApps.  
Besides the good practices governments have been proposing to handle these issues [175], the Blockchain technology has been seen as a good solution [176; 177] for empowering citizens over their data control (self-sovereign identities) and promote reliable cities' transportation systems. For instance, instead of each application collecting user's personal data to manage their transport system, and acting individually to try to satisfy their clients' motion around, the DApps can privately share individual motion data between several transportation systems in order to allow a better data management. This data sharing would be enabled only by specific users' digital signatures over the piece of information they agree to share.  
Considering these points, Blockchain appears as a new trend in the area of urban management, balancing data control and flow of money between parties (as will be detailed in Section 3.5.4). Thus, its use opens a completely new mindset where fully-distributed solutions are feasible. In addition to strengthening the use of more competitive tools, the population should be conscious about the possibilities of interacting with intelligent cities' systems, as well as being aware of the data that is being measured and stored. Blockchain based technologies are a disruptive manner of balancing efficiency and trust regarding the use of data measured inside cities'. In addition, such systems have been advocated as more robust and resilient, as well as censorship resistance, which are desirable components for public transportation systems.  
Figure 4: A draft of some functions that could be called for registering operations on the NEO Blockchain, designed with the assistance of [[https://neocompiler.io](https://neocompiler.io)]([https://neocompiler.io](https://neocompiler.io)).  
These fully distributed systems are able to interact with cryptocurrencies and the services they provide, promoting the emergence of a true IoV. For example, social car pulling could be done by means of automatic smart contracts, which would surely increase transparency and reduce administrative costs. These platforms that contain personalized virtual machine environment comes as an alternative for providing infrastructure to several new startup projects [178].