Search Results (8)

Uninterrupted traffic flow monitoring is a prerequisite for optimal resource allocation and minimizing vehicular emissions in smart cities. However, centralized traffic management architectures are highly vulnerable to single points of failure. When structural sensor malfunctions occur, the resulting network unobservability paralyzes dynamic signalization, triggering cascading traffic congestion, extended idling times, and severe greenhouse gas emissions. To address this cyber-ecological vulnerability, we propose the Hybrid Multi-Agent State Estimation (H-MASE) protocol, a fully decentralized decision-support framework designed from an applied systems reliability engineering perspective. By deploying PSAs and VLAs directly onto IoT-enabled edge devices at smart intersections, H-MASE leverages a hop-by-hop edge computing topology to collaboratively track macroscopic route flow dynamics. Mathematically, this distributed estimation process is formulated as a network-wide least-squares convex optimization problem, where local projection operators function as exact Distributed Gradient Descent steps to minimize the global residual sum of squares. The distributed consensus mechanism acts as a spatial variance reduction tool, effectively dampening measurement noise and stochastic demand fluctuations. Furthermore, we introduce an autonomous anomaly detection logic that isolates severe structural faults rapidly, which is mathematically structured to prevent false alarms under bounded disturbance conditions. Numerical simulations demonstrate that the protocol yields a highly resilient optimality gap (e.g., a Root Mean Square Error of merely 0.81 vehicles per estimated state) even under catastrophic hardware failures. Ultimately, H-MASE provides a robust, fail-safe data foundation for sustainable urban logistics and green-wave signalization, ensuring that smart cities maintain ecological resilience and optimal resource utilization under severe structural disruptions. Full article

This paper presents an edge-to-cloud orchestrator capable of supporting services running at the edge on heterogeneous nodes based on general-purpose processing units and Field Programmable Gate Array (FPGA) platform (i.e., AMD Kria K26 SoM) in an urban environment, integrated with a series of cloud-based services and capable of minimizing energy consumption. A use case of vehicle traffic monitoring is considered in a mobility scenario involving computing nodes equipped with video acquisition systems to evaluate the feasibility of the system. Since the use case concerns the monitoring of vehicular traffic by AI-based images and video processing, specific support for application orchestration in the form of containers was required. The development concerned the feasibility of managing containers with hardware acceleration derived from the Vitis AI design flow, leveraged to accelerate AI inference on the AMD Kria K26 SoM. A Kubernetes-based controller node was designed to facilitate the tracking and monitoring of specific vehicles. These vehicles may either be flagged by law enforcement authorities due to legal concerns or identified by the system itself through detection mechanisms deployed in computing nodes. Strategically distributed across the city, these nodes continuously analyze traffic, identifying vehicles that match the search criteria. Using containerized microservices and Kubernetes orchestration, the infrastructure ensures that tracking operations remain uninterrupted even in high-traffic scenarios. Full article

Accurate traffic flow detection plays a critical role in intelligent traffic control systems. However, conventional fixed video detection devices often face challenges such as occlusion and overlap in high-density traffic scenarios, which leads to distortions in vehicle detection. To address this issue, it is essential to obtain precise vehicle data as a reliable reference for managing traffic flow during peak periods. In this paper, we propose an intelligent detection scheme using an improved YOLOv8n target recognition algorithm combined with a ByteTrack multi-target tracking algorithm. A collaborative unmanned aerial vehicle (UAV) collaborative detection framework is also established, integrating UAVs and fixed detection devices to work in tandem. Such a multi-UAV collaborative data acquiring system is designed for efficient, continuous, and uninterrupted operation, employing a three-drone rotational detection strategy. UAVs offer additional flexibility and coverage in obtaining vehicle data. However, limited power could be an essential challenge to the system’s wireless physical link stability and safety. To overcome power limitations during UAV collaboration, a wireless charging (WC) system is introduced, enabling automatic constant current–constant voltage (CC-CV) switching and preventing damage from accidental data link disabling. This collaborative traffic data acquiring and transmission system ensures a stable power supply for UAVs during high-density traffic periods, supporting their reliable UAV collaborative wireless data link. Experimental results show that the collaborative detection architecture combined with wireless charging can achieve high detection accuracy, with the recognition accuracy remaining between 0.95 and 0.99. Full article

This study examines the significant impact of Houthi insurgent activities on maritime traffic within the strategic Red Sea and Suez Canal routes, essential conduits for global trade. It explores the correlation between regional instability, exemplified by Houthi actions from 19 November 2023 to 5 February 2024, and changes in maritime traffic patterns and operational efficiency. This study seeks to answer a critical question in transport geography: how does regional instability, exemplified by Houthi insurgent activities, affect the maritime traffic patterns and operational efficiency of the Red Sea and Suez Canal? Using descriptive statistics, qualitative analysis, and geospatial methods, this research highlights recent trends in maritime traffic and incidents, revealing spatial and geopolitical challenges in this crucial trade route. The findings indicate a notable decline in maritime activity in the Gulf of Aden and Suez Canal due to security concerns from Houthi attacks, prompting a significant shift to alternative routes, particularly around the Cape of Good Hope. This shift underscores the broader implications of regional instability on global trade and the importance of maintaining an uninterrupted maritime flow. This study also emphasizes the economic ramifications, such as increased operational costs and freight rates due to longer transit times and enhanced security measures. This research concludes with a call for improved maritime security protocols and international cooperation to protect these strategic maritime pathways. It contributes to the discourse on transport geography by quantifying the direct impacts of regional conflicts on maritime logistics and proposing strategies for future resilience, highlighting the interconnected nature of global trade and security and the need for collective action against evolving geopolitical challenges. Full article

The fundamental relationship of traffic flow and bivariate relations between speed and flow, speed and density, and flow and density are of great importance in transportation engineering. Fundamental relationship models may be applied to assess and forecast traffic conditions at uninterrupted traffic flow facilities. The objective of the article was to analyze and compare existing models of the fundamental relationship. To that end, we proposed a universal and quantitative method for assessing models of the fundamental relationship based on real traffic data from a Polish expressway. The proposed methodology seeks to address the problem of finding the best deterministic model to describe the empirical relationship between fundamental traffic flow parameters: average speed, flow, and density based on simple and transparent criteria. Both single and multi-regime models were considered: a total of 17 models. For the given data, the results helped to identify the best performing models that meet the boundary conditions and ensure simplicity, empirical accuracy, and good estimation of traffic flow parameters. Full article

External costs that are associated with air pollution, climate change linked to greenhouse gas emissions (GHG), and noise are among the most important environmental externalities that are generated by road transport, which have been well monetized. This paper theoretically investigates the effects of different traffic conditions on the environmental external costs of urban roads where traffic flow is more complicated than un-interrupted traffic flows. A Monte Carlo method is used to theoretically simulate traffic speed in different traffic conditions. Subsequently, the emitted carbon dioxide ($C{O}_2$), nitrogen oxides ($N{O}_x$), carbon monoxide ($CO$), particulate matter ($PM$), sulfur dioxide ($S{O}_2$), and noise were estimated in each of the theoretically simulated traffic conditions. Finally, the environmental external costs in each traffic condition were calculated taking the EU average costs values into account. The results showed that, when compared to free-flow condition, the total air pollutant and GHG external costs (€2010) have been increased by 6%, 31%, 44%, 50%, and 93% in under-saturated flow, accelerated flow, decelerated flow, congestion, and over-saturated congestion, respectively. Furthermore, the total noise cost (€2010/year/person exposed), as compared to free-flow condition, has been decreased by 2%, 11%, 12%, 36%, and 69% in accelerated flow, under-saturated flow, congestion, over-saturated congestion, and decelerated flow, respectively. Full article

For uninterrupted traffic flow, it is well-known that the fundamental diagram (FD) describes the relationship between traffic flow and density under steady state. To study the characteristics of interrupted traffic flow on a signalized link, a link fundamental diagram (LFD) for urban roads is proposed in this paper. First, a new variable, which synthesizes traffic flow with the speed of each vehicle, is defined. Then, the link fundamental diagram is obtained by drawing a scatter-plot of the velocity-weighted flow versus queue length, which takes on a unimodal curve with an approximately symmetric shape. Finally, simulation studies are conducted by modeling an urban link based on the traffic simulation software VISSIM. Compared with the traditional fundamental diagram, the proposed link fundamental diagram is more intuitive for showing the relationship between traffic condition and queue length. The impacts of the cycle time, green time, and split on the proposed link fundamental diagram are studied. Simulation results show that the shape of the link fundamental diagram fundamentally is determined by the split. The critical point is correlated to split values, and the green time exerts a great influence on both the velocity-weighted flow and the critical queue length. The cycle time has little effect on the critical queue length but has a great influence on the velocity-weighted flow. Full article

The paper suggests a methodological approach for assessing the sustainability of the urban transport system. Parameters were selected for assessing the sustainability of the transport system and significant factors affecting sustainability were determined. Parameters of the sustainability of the system when changes in the weather and road conditions affect vehicle operation were estimated on the basis of the simulation modeling. An integral indicator of sustainability was introduced to evaluate the sustainability of the transport flow management subsystem and the methodological approach to its calculation was substantiated. The results from changing the parameters of the traffic flow were demonstrated in the case of a significant amount of precipitation and the constraints put on the movement of vehicles on the road infrastructure unit due to snow-removal operations and road traffic accidents. Also, the parameters of road traffic under the reconstruction of the main street of regulated traffic into a street of uninterrupted traffic were presented. Full article