Abstract: In order to reveal the car-following characteristics of human-machine mixed driving traffic flow in rainy weather, starting from analyzing the impact of rainfall on driving, parameters such as road adhesion coefficient and driving visibility were introduced to improve Gipps safety distance and driving acceleration limitation. Cellular automata models were established for different car following modes, and simulation experiments were designed to explore the car-following characteristics of human-machine hybrid traffic flow under the dual effects of rainfall intensity and permeability. The numerical simulation results show that: the penetration rate on rainy days is positively correlated with traffic capacity, but when the penetration rate is below 0.25, the impact of connected and autonomous vehicle (CAV) on the average speed, critical density, and traffic capacity of mixed traffic flow is limited. When the rainfall intensity is higher than 0.3 mm/min, as the rainfall intensity increases, the car-following degradation of CAV will be exacerbated, which significantly reduces the free speed, critical speed, and traffic capacity of the mixed traffic flow. Under light rain conditions, a penetration rate of about 0.1 can compensate for the loss of traffic capacity caused by rainfall. In the rain intensity range from moderate to heavy rain, for every 0.1mm/min increase of rain intensity, the corresponding increase in penetration rate is 0.1. The traffic capacity of the road section can be restored to a level equivalent to that of pure human-driving traffic flow on sunny days.

Key words: traffic and transportation engineering; human-machine mixed driving; traffic flow; car-following characteristics; rainfall intensity; cellular automata

摘要： 为揭示降雨天气下人机混驾交通流跟驰规律，从分析降雨对行车的影响入手，引入路面附着系数、驾驶能见度等参数，改进Gipps安全距离和行车加速度限制，针对不同跟驰模式建立元胞自动机模型，探寻降雨强度、渗透率双重影响的人机混驾交通流跟驰特性。数值仿真结果表明：雨天渗透率与通行能力呈正相关，但当渗透率低于0.25时，智能网联车对混合交通流平均速度、临界密度及通行能力的影响有限；当降雨强度高于0.3 mm/min时，随雨强度增大会加剧智能网联车跟驰退化，显著降低混合交通流的自由速度、临界速度及通行能力；小雨情况下，约0.1的渗透率可弥补降雨造成的通行能力损失；在中雨至大雨的降雨强度区间内，降雨强度每增加0.1 mm/min，相应提高渗透率0.1，路段通行能力可恢复到与晴天纯人工驾驶交通流相当的水平。

关键词: 交通运输工程；人机混驾；交通流；跟驰特性；降雨强度；元胞自动机