The theoretical analysis of traffic flow with empirical vehicle trajectory data contained within this study allows for the explanation, reconstruction, and prediction of spatiotemporal transition characteristics of traffic conditions. Using an unmanned aerial vehicle (UAV) during a morning rush hour on a working day, observations of congestion evolution near an on-ramp bottleneck of an expressway was captured. The empirical high-fidelity trajectory data of 621 vehicles were extracted. The major findings include:

(1) Macroscopic perspective: Three traffic states (free flow, metastable traffic flow, and jam) were observed with different spatiotemporal physical structures and their critical characteristics in a continuous first-order phase transition. The spontaneous spatiotemporal traffic breakdown and capacity drop were also captured, the critical points of which were also recorded. The features of widening synchronized flow pattern, general pattern, and the nature of nucleation described in the three-phase traffic theory were identified, which provides a new observational cognition for congestion formation and development.

(2) Microscopic perspective: The impact of lane changes on immediate vehicles were modeled and quantified with the fluctuation magnitude of speed and the theoretical lag distance, which provides a method to identify the source of perturbation and determine the microscopic critical threshold of vehicle between macroscopic phase transitions. The research shows a lane changer could cause a forced deceleration of an immediate vehicle on a target lane after inserting itself with critical spacing headway below approximately 15–20 m. The average deceleration duration of vehicles in different traffic states can be captured as crucial driving features from downstream to help predict traffic state transition in a real bottleneck.

本研究中包含的经验车辆轨迹数据对交通流量进行理论分析，可以对交通状况的时空过渡特征进行解释，重建和预测。在工作日的早上高峰时段，使用无人飞行器（UAV）捕获了高速公路匝道附近瓶颈处拥堵演变的观察结果。提取了621辆汽车的经验高保真轨迹数据。主要发现包括：

（1）宏观角度：在连续的一阶相变中，观察到三种交通状态（自由流动，亚稳态交通流动和拥堵），它们具有不同的时空物理结构及其临界特性。还捕获了自发的时空交通故障和容量下降，并记录了其临界点。识别了三相交通理论中描述的同步流模式的拓宽，一般模式和成核性质，为拥塞的形成和发展提供了新的观测认识。

（2）微观视角：通过速度波动幅度和理论滞后距离对车道变更对即时车辆的影响进行建模和量化，为识别扰动源和确定宏观之间车辆微观临界阈值提供了一种方法。相变。研究表明，换道器插入其自身的临界间距小于约15–20 m后，可能会在目标车道上造成即时车辆的强制减速。处于不同交通状态的车辆的平均减速持续时间可以从下游获取为关键的驾驶特征，以帮助预测实际瓶颈中的交通状态转变。