## 6 Conclusions  
This study provided insights into how HDV drivers perceive and interact with CAVs on the road. First, five psychological parameters of HDV drivers facing CAVs were identified in accordance with the theory of planned behavior. As indicated by the result of the latent profile analysis, three heterogenous individual clusters were identified (i.e., negative individuals, neutral individuals, and positive individuals). The psychological characteristics of the respective cluster were defined following an ANOVA. Negative individuals were likely to gain few insights into CAVs, had suspicion of CAV performance, and had the most passive attitude towards sharing the same road as CAVs. And this cluster had poor risk awareness and confidence when driving on the road mixed with CAVs. The neutral individuals have an average of neutral in relation to most of the psychological variables, and they had relatively strong risk awareness when sharing the same road as CAVs. Positive individuals, obviously, had the highest familiarity and trust in the CAVs and the most optimistic attitude towards sharing the same road as CAVs. Second, using a multinomial logistic regression model, we investigated the correlation between the latent clusters and socio-demographic variables. The results showed that gender, age, the highest level of education and annual driving mileage parameters were not statistically significant. In terms of income, the respondents with a low income (less than RMB 5000 per month) and middle income (RMB 5000-10,000 per month) were more likely to be negative towards CAVs. In terms of the effects of driving experience, the drivers who had driven for more than ten years were significantly more likely to be negative towards CAVs. In addition, the drivers who had driven or taken a CAV were more likely to be in the positive cluster. Lastly, cluster-based choice behaviors in five interacting driving scenarios were analyzed based on multinomial logistic regression. The result suggested that positive individuals had stronger car-following willingness when the leading vehicle was a CAV. When noticing a CAV platoon driving in the target lane, negative individuals were more likely to give up on changing lanes. In addition, if lanes were changed, negative individuals and neutral individuals were more likely to accelerate and drive in front of the CAV platoon. When realizing the leading or rear vehicles in the target lane were CAVs during the lane-changing process, negative individuals were more likely to increase the requirement for the vehicle spacing while positive individuals would reduce the corresponding requirement. Notably, no significant differences was reported in the car-following distances between the above-described three clusters, consistent with the field test results [58]. This study revealed the factors for HDV drivers' subjective feelings towards CAVs. The results confirmed that the choice behavior under an interactive driving scenarios can be significantly affected by a drivers' psychological characteristics when they face CAVs. The findings, to a certain extent, have vital policy significance for government agencies and CAV producers. (1) Education for HDV drivers  
One of the major concerns regarding CAVs is how CAVs are promoted and how well people understand CAVs. Thus, HDV drivers should realize the safety and other potential benefits that CAVs may provide. Government agencies could make promotional videos or brochures to introduce a CAV's advanced techniques and driving performance for drivers with different level of driving experience. CAV producers should create opportunities for the public to experience autonomous vehicles to help drivers gain insights into CAVs following their practical experience. (2) Lane management strategies  
From a policy perspective, many uncertain risks will be generated related to the high level of interaction between CAVs and HDVs. For instance, [PERSON] et al.