## 1 Introduction  
Hazardous chemicals are basic raw materials that are indispensable for people's production and life. Road transportation is the best choice for the logistics transportation of hazardous chemicals [1]. As hazardous chemicals are flammable, explosive, and highly toxic, accidents in transit lead to leaks, fires, and explosions [2], resulting in casualties, property damage, environmental pollution, ecological damage, and other serious consequences. For example, on 2 January 2022, a heavy semi-trailer tanker collided with a vehicle moving in the opposite direction in Jiangyou city, Mianyang, Sichuan Province, resulting in eight deaths, 20 injuries, and direct economic losses of approximately 11.35 million yuan. On 11 March 2022, a heavy-duty warehouse truck lost control within the section of Ebao Town, Qilian County, on National Highway 227 and crashed into the temporary checkpoint of Ebao, resulting in seven deaths, two injuries, and direct economic losses of approximately 3.513 million yuan; additionally, the surrounding houses and environment were damaged to different degrees. All these accidents have brought significant losses and exerted negative social impacts on the country and its people. The road transportation system of hazardous chemicals is a complex and huge system. Its safety is easily disturbed by the fuzziness and randomness of many influencing factors, which makes it difficult to determine the risk of road transportation accidents of hazardous chemicals. How to consider the fuzziness and randomness and accurately evaluate the risk of road transportation accidents of hazardous chemicals, so as to take effective measures to prevent and control them, has become a social problem that needs to be solved. The problem of the risk evaluation of hazardous chemical road transportation accidents has received increasing attention from scholars in China and elsewhere. Fuzzy comprehensive evaluation [3], gray theory [4], and other probabilistic risk assessment methods have been widely used in the safety assessment of the road transportation of hazardous chemicals. The fuzzy comprehensive evaluation method considers the fuzziness of the influencing factors, but does not consider their randomness. The gray prediction model is very simple to implement, but it ignores the correlation between various factors, relies heavily on historical data, and may produce huge errors that cannot reflect the actual situation well [2]. The cloud model theory provides many novel strategies for solving more complex problems in the field of decision-making. [PERSON] et al., 2020 [5], constructed a tunnel water inrush risk assessment model by combining the analytic hierarchy process and the cloud model, and applied and verified the model in practice. [PERSON] and [PERSON] [6], 2020, proposed a cloud model evaluation method to evaluate the safety status of highways and their supporting facilities. Therefore, the combination of the analytic hierarchy process and cloud models can be applied in the transportation of hazardous chemicals on roads. Compared with traditional fuzzy evaluation, which relies on the affiliation function provided by experts' a priori knowledge or obtained through statistical methods, a cloud model can effectively reflect the fuzziness and randomness in the data of evaluation indices, making the evaluation results more accurate and reasonable. Therefore, the cloud model is superior to the fuzzy comprehensive evaluation method and the gray theory evaluation method in solving the uncertainty problem. Due to the uncertainty of the risk evaluation system for hazardous material road transport accidents, further research on the fuzziness and randomness of the evaluation process is needed. Cloud models have been widely used to address uncertainty problems in many fields. However, there are few studies on the application of cloud modeling to the risk evaluation of hazardous chemical road transport accidents.