arXiv subjects

Xiaolu Jia

Publications and source records attributed to Xiaolu Jia.

5 recordsLinked to original sources

arXiv2026

Effect of vehicle groups on heterogeneous disordered traffic flow

In heterogeneous disordered traffic, where various vehicle types operate without strict lane discipline, self-organized vehicle groups often emerge, but their influence remains unclear. This study examines how group prevalence and composition affect flow-density relationships using real-world trajectory data. Three Passenger Car Unit (PCU) estimation methods construct flow-density diagrams accounting for heterogeneity. Group proportion, the share of vehicles classified in groups, has a nonlinear, traffic-situation-dependent impact on flow. Moderate group proportions (30-60%) were more clearly associated with peak-flow or high-flow cases under denser traffic conditions, rather than consistently producing the highest representative flow in the median-based analysis. Comparing vehicle-count-based and PCU-based group proportions shows that normalization affects interpretation, particularly when groups consist mainly of small-PCU vehicles such as motorcycles. Lower group proportions were associated with relatively favorable flow under free-flow conditions, while entropy-based analysis shows that the association between entropy alone and speed is not consistent across traffic situations. Contrasting representative trends and extreme high-flow cases suggests that traffic at similar density and group proportion can exhibit low-efficiency and high-efficiency modes. Overall, group prevalence is important in shaping macroscopic traffic dynamics, while linking internal group composition to performance may require richer structural descriptors beyond a single entropy measure. These results imply condition-dependent bottom-up traffic control: encouraging favorable vehicle formations in denser traffic and preserving fluid leader-follower relations in free-flow traffic may improve heterogeneous traffic flow, especially with minimal infrastructure or driver-assistance technologies.

physics.soc-ph↗

arXiv2026

Conflict Avoidance in Pedestrian Merging in Controlled Experiments by Variance Indicator

Pedestrian congestion at corridor intersections often originates from localized fluctuations in motion rather than from a macroscopic collapse of flow. Understanding pedestrian instability at corridor intersections remains challenging because existing studies mainly rely on density, average speed, or flow-based measures and limited datasets, making it difficult to separate geometric turning effects from interaction induced fluctuations in merging flows. In particular, the mechanism underlying the turning angle dependence in T junctions has not been resolved. Here, we analyze more than 300 controlled experiments conducted in L corridors with turning only and T corridors with turning and merging. Using Voronoi-based speed variance $V_s$ and velocity variance $V_v$, we systematically compare geometric and interaction effects. $V_s$ effectively captures interaction driven instability, while $V_v$ reflects directional adjustments due to geometry. The comparison reveals distinct fluctuation mechanisms and identifies a critical transition near $90°$, demonstrating the advantage of variance-based indicators for diagnosing pedestrian dynamics.

physics.soc-ph↗

arXiv2022

Optimization of transition behaviors in a two-lane system

Transitions between two lanes often have a significant impact on various forms of road traffic. To address this problem, we have developed a two-lane asymmetric simple exclusion process model and two hypothetical traffic control strategies, to simulate a futuristic scenario where the timing and location of transitions between two lanes are highly controlled. Various scenarios were proposed to study the effectiveness of these control strategies. An optimized control strategy, whose parameters were determined through an optimization algorithm, is confirmed to effectively maximize the average traffic flow. Consequently, we may identify suitable road sections and the corresponding timings of transitions to resolve congestion in this model.

physics.soc-ph↗

arXiv2019

Experimental study on the evading behavior of individual pedestrians when confronting with an obstacle in a corridor

In this paper, controlled experiments have been conducted to make deep analysis on the obstacle evading behavior of individual pedestrians affected by one obstacle. Results of Fourier Transform show that with the increase of obstacle width, the frequency and amplitude of body sway would barely be affected while the lateral deviation of walking direction would largely increase. On the one hand, the relation among the extracted gait features including body sway, stride length, frequency and speed has been illustrated. On the other hand, the walking direction can be featured by three critical evading points where apparent change of walking direction could be observed. Gaussian function has been used to fit the walking direction, thus allowing to estimate the three critical points and examine their variation with the increase of obstacle size. Furthermore, the direct-indirect evading and left-right turning preference as well as the possible psychological motivations behind have been analyzed. It is indicated that direct-evading pedestrians have a higher walking efficiency and right-turning pedestrians have a stronger tendency to behave `direct'. Results of this paper are expected to provide practical evidence for the modeling of pedestrian dynamics affected by obstacles.

physics.soc-ph↗

arXiv2018

Pedestrians rotation measurement in bidirectional streams

This study presents an experimental measurement of pedestrians' body rotation in bidirectional streams. A mock-up corridor monitored using a camera placed on azimuthal position is used to study pedestrians' behavior in unidirectional and bidirectional flows. Additionally, a commercial tablet is fixed on the chest of sample pedestrians to examine their body rotation (or yawing) which cannot be obtained using position tracking alone. Angular velocity is recorded and simultaneously stored in a central location using a wireless network, thus allowing the analysis of body movements with a high sampling rate and a limited delay. To investigate the influence of major/minor flow proportion (flow-ratio) on bidirectional streams two different situations were tested: the balanced configuration (with equal flows in both directions) and an unbalanced configuration (with different major and minor flow). Results clearly show that unidirectional flow is more stable compared to the bidirectional case, requiring less time to cross the experimental section and showing a very small amount of rotation during the whole experiment. Both bidirectional configurations showed high values of body rotation, in particular during lane formation and dissolution. Finally, rotation directly measured on pedestrians' body was compared with the one obtained indirectly by analyzing pedestrians' trajectories. The comparison shows that, at least from a qualitative point of view, both methods are in agreement, thus suggesting that even properties which can only be measured by motion sensing could be obtained indirectly through the analysis of trajectories. Concluding, it has been suggested that while lanes help smooth out bidirectional flows, larger instabilities are observed compared to the unidirectional case. Lane separation and/or appropriate guidance are therefore required.

physics.soc-ph↗