“…As shown by the CMFs of SMR, the percentage of light/medium rainfall in a season significantly impacts the safety of CS, SAS, SS, and THS (as shown in Table 9 and Figure 6), with these impacts being more pronounced for interchange segments: when the SMR is reduced from 40% to 10%, the average crash rates reduce by 65.38%, 74.89%, 39.55%, and 23.27% for CS, SAS, SS, and THS, respectively. Sawtelle et al (2023) [44] showed that the monthly average daily precipitation on Chinese freeways is positively correlated with crash frequency, supporting this paper's view. In fact, the impacts of rain on freeway safety are mainly reflected in (1) reduced visibility for drivers, thus compressing the space for safe operation, and (2) reduced traction between the road surface and tires, especially in segments with more heavy vehicles, which are more likely to lose control.…”