Table 3 Summary of key literature contributions.

Blockchain in Transportation Systems

^{1,2,3,4,5,6,7}

Enhanced data security and privacy in transportation networks; Multi-layered blockchain approaches for smart mobility; Integrated fleet management systems; Optimized traffic flow and safety through secure data exchange.

Limited scalability for large-scale deployments; Insufficient interoperability with existing systems; High computational requirements restricting real-time applications; Lack of standardized approaches across different transportation domains.

Blockchain and IoT Integration

^{8,9,10,11,15,20,21,22}

Secure data verification systems for urban surveillance; Smart campus implementations with blockchain-IoT integration; Convergence of AI and blockchain for sustainable development; Enhanced security mechanisms for IoT environments; Smart contracts enabling automated trust in distributed systems.

Challenges in handling resource-constrained IoT devices; Limited attention to device heterogeneity; Insufficient optimization for energy efficiency; Privacy concerns in data collection and processing; Lack of standardized protocols for secure communication.

Data Management and Analytics

^{12,13,14,16,23,24,25}

Blockchain-based big data analytics frameworks; IoT-fog communication models for distributed data management; Intelligent architectures combining blockchain and AI; Fog computing platforms for smart city applications; Enhanced security for big data in distributed environments.

Scalability issues with large datasets; Computational overhead in real-time analytics; Limited standardization in data formats and protocols; Insufficient attention to data privacy regulations; Challenges in integrating with legacy systems.

Security and Privacy Frameworks

^{17,18,19,26,27,28,29}

Comprehensive security models for blockchain applications; Domain-specific implementations in healthcare and other sectors; State-of-the-art consensus protocols addressing fault tolerance; Privacy-preserving mechanisms for sensitive data; Social aspects of blockchain adoption for inclusive communities.

Fragmented approaches to security across different domains; Insufficient attention to emerging threats; Limited real-world validation in diverse environments; Challenges in balancing security with usability; Lack of standardized security assessment methodologies.

Consensus Mechanisms and System Architecture

^31,32,33,34

Overview of consortium blockchains for controlled environments; Cybersecurity frameworks combining blockchain and federated learning; Geospatial blockchain systems for location-based services; Efficient blockchain frameworks optimized for smart cities; Bibliometric analyses identifying research trends.

Energy-intensive consensus mechanisms limiting IoT applications; Scalability constraints in high-density environments; Insufficient adaptation to dynamic network conditions; Limited cross-chain interoperability; Trade-offs between security, scalability, and decentralization not fully addressed.

Governance and Integration Frameworks

35–38

Applications for sustainable urban development; Unified blockchain ecosystems for system integration; Structured approaches to smart city implementation; Governance toolboxes for effective management and oversight.

Limited alignment with existing regulatory frameworks; Insufficient stakeholder engagement models; Challenges in cross-jurisdictional implementations; Lack of standardized governance protocols; Limited attention to socioeconomic implications of blockchain adoption.