Abstract: In order to identify risk factors in road transportation system of dangerous goods and prevent transportation accidents from the source, the N-K model was used to analyze the system risk coupling. Firstly, risk factors were divided into five categories: human, machine, material, environment and management. Then according to the number of risk factors involved in the coupling, single, double, triple, quadruple and five factors coupling risks were divided, and the N-K model was used to calculate the coupling risk values of various couplings. Finally, taking 220 road dangerous goods transportation accidents in China in the first half year of 2017 as examples, the system coupling risk was calculated. The results show that the more risk factors involved in coupling, the greater the coupling risk value will be, that the risk of coupling between human and environment is the greatest and that between material and management is the smallest, and that coupling risk between subject and objective is relatively large while the risk of multiple subjective factors coupling with each other is smaller.

Key words: road transportation, dangerous goods, risk analysis, N-K model, coupling risk