# Leveraging Digital Twin Technology for Sustainable and Efficient Public Transportation
## 3 Challenges and Limitations of Digital Twins
### Privacy  
The implementation of DTs in public transportation must also consider the policies and concerns surrounding data privacy. The policies regarding data collection, usage, and sharing to build trust with users and stakeholders must be clearly upheld by organizations. One example of privacy and policy implication is that technology must be compliant with legal frameworks, such as the General Data Protection Regulation (GDPR), to ensure that user data are handled responsibly and ethically [112]. Communication methods in DT environments are also critical to ensure data privacy. One study presents a privacy-preserving communication scheme using blockchain technology to secure data exchanges in cloud-based DT environments. The authors highlight the effectiveness of blockchain in providing a decentralized approach to data security, which is applicable in bus transportation systems where sensitive passenger data are transmitted frequently and in real time [48]. The authors of another study also point out the need for robust security measures in 5G-integrated IoT environments by exploring privacy-preserving schemes in smart transportation [29].  
A study provides a comprehensive survey of security threats associated with digital twin technologies by breaking down potential security threats to digital twins (DTs) into clear categories to understand the risks involved in using them. The authors emphasize the reliance on the combination of multiple technologies, and how the connection to the physical world can create unseen security challenges. By examining the holistic approach to security and operation and identifying possible weak points, the authors discuss potential vulnerabilities that could arise when deploying DTs [107]. In addition to technological solutions, organizational strategies play a crucial role in protecting data privacy. Organizations can implement cloud-based solutions to protect sensitive data as well as user privacy in intelligent transportation applications to address both technical and organizational challenges [108].  
The authors of one study discussed the integration of advanced technologies such as 6G networks to enhance the performance and security of digital twin edge networks. However, these advancements also require a reassessment of existing security and privacy measures to address the unique challenges posed by next-generation connectivity. The authors suggest a proactive approach to security that uses the capabilities of emerging technologies to create resilient transportation systems [30].  
Furthermore, the role of user awareness and education in mitigating privacy and security risks is also essential to the smooth operation of DT technology. A well-informed and trained workforce is essential for managing security risks and implementing the best practices in DT systems. Training in cybersecurity, data privacy, and interoperability can strengthen transportation networks. Similarly, public awareness campaigns can enhance transit users' understanding of operations and importance of data security and allow continuous feedback to be gained, to improve overall DT systems. One study highlights the importance of user education in smart grid environments, which is also applicable to smart transportation systems [31]. The authors of another study discussed the importance of user engagement to develop secure IoT applications. This can foster a culture of security awareness among users, and organizations can ultimately enhance the overall security of their transportation systems as well [32].