State-of-the-art of Blockchain Technology in Intelligent Transportation Systems: Literature review

In recent years blockchain technology has become a popular topic for research in multiple fields of discipline. For the transport sector especially, the technology is seen as disruptive. Because the research field is young and the research on the topic is developing fast, state-of-the-art knowledge is exclusive to a select group of academics. This review aims to provide an overview of the current state of blockchain technology applications in the transportation domain. Previous reviews on blockchain and transportation have already mapped the contributions for supply chain and logistics. Studies within the transportation domain on connected systems and vehicles have not been comprehensively reviewed, while the relevance on these kind of systems is growing. The focus of this review is on Intelligent Transportation Systems (ITS), which integrates the connected transportation systems and vehicles. The demand for ITS is growing and the relevance of supporting blockchain solutions as well. The increasing amount of connected vehicles introduce security and privacy concerns. Connected vehicles share sensitive information on which other users base their behaviour, so correctness of information is very important. Next to that, the risk arises of losing complete control over the vehicle through attacks due to the remote accessibility possibilities of the vehicle. Blockchain offers a solution for these concerns by enabling a decentralized and secure way of sharing information. These features make secure and trustworthy communication between vehicles, roadside units and platoons possible, aswell as secure over-the-air software updates. Privacy concerns can be mitigated via the use of pseudonyms, partitions or fresh data keys. With its decentralized characteristic, blockchain technology creates a transparent and traceable way of storing and sharing data. For ITS applications this means efficient insurance processes and liability attribution. Furthermore, the traceability feature of blockchain can be used in fraud detection for rolling wrecks and odometer fraud. Also, ITS can benefit from blockchain technology by integrating smart contracts. Processes where a third party is involved can be replaced by a smart contract, making it possible to implement vehicle-to-machine payments. This makes transactions fast, cheaper and secure. Processes like tolling payments or vehicle maintenance can then be automated. The security and privacy features of blockchain technology offer a solution for the implementation of Mobility-as-a-Service principles, which enables vehicle sharing. Furthermore, blockchain is an asset for transportation solutions in smart cities. In smart cities, blockchain technology can ensure data integrity and encourage organizations to share data enabling transparent city management. Within smart cities, blockchain can facilitate the data sharing between vehicles and infrastructure, as well as energy trading via vehicle-to-grid principles. Another way in which ITS can benefit from blockchain technology, is through the use of incentive mechanisms. Blockchain is well suited for incentive systems because it can automate direct interaction between actors. With automated payments, people can be incentivized to share reliable traffic data or to participate in efficient energy distribution for the grid. Also, safe driving behaviour and environmental friendly transportation can be rewarded. Before real life systems can benefit from the advantages of blockchain technology a lot of challenges have to be overcome. For ITS, all applications exist only in theoretical form. Challenges that have to be faced are the high energy consumption, latency and throughput constraints, and governance issues. Although the benefits of blockchain technology are multifold, the challenges have proven to be to hard to overcome up until now.Mechanical Engineerin