为了研究高速公路减速波事故的前兆交通特征，选用了美国I880 高速公路的一条路段的交 通流数据和事故数据，从减速波事故的产生机理出发，通过跟驰行为的安全条件，推导出减速波事故前兆特征因子的交通状态表达方法。分析发现，高速公路上下游速度差和上游交通密度是减速波事故的两个前兆特征因子，上下游速度差和上游交通密度越大，高速公路减速波事故发生的 概率越高。基于此，描述了减速波事故发生概率与高速公路上下游速度差和上游交通密度的数学关系，并进一步建立了减速波事故概率模型，应用所采集的数据拟合了提出的事故概率模型。结 果显示，模型的拟合度为0.673，说明减速波事故发生概率与其前兆因子存在正相关关系，预测模型在一定程度上可以反映真实概率的大小。

In order to study the precursory traffic characteristics of expressway deceleration wave accident, started from the mechanism of deceleration wave accident, traffic flow data and accident data of the US I880 Expressway were selected for deducing the traffic state expression method for the precursory characteristic factors of deceleration wave through the safety car-following conditions. The analysis demonstrated that the velocity difference between upstream and downstream and the upstream traffic density of the expressway were the two precursory characteristic factors of the deceleration wave accident. The greater the velocity difference between upstream and downstream and the higher the upstream traffic density, the higher the probability of the accident occurred on the expressway. Based on this, the mathematical relationship between the probability of occurrence of deceleration wave accident and its precursory factors was described, further the probability model of deceleration wave accident was established, and the model was fitted by the data collected. The results show that the fitting degree of the model is 0.673, which proves that the accident probability of the deceleration wave has positive relation with its precursory factors. This model can reflect the true probability to a certain extent.