*4.2. Discussion*

The 69-car collision on the Virginia Expressway in December 2019 and the tra ffic collision on the Yeongcheon Expressway in Korea in December of the same year were all caused by black ice. As such, casualties from black ice accidents continue to occur worldwide. To prevent this, measures such as installing grooving (a construction method that makes small grooves on the surface of the road to reduce braking distance), installing LED signs, and installing heat wires on the road are currently being proposed. However, since the proposed measures are not a preliminary measure to prevent accidents, a proactive strategy to prevent black ice accidents is being devised. Accordingly, the study was conducted to detect black ice in advance using AI methodologies to extract high accuracy. As further confirmed earlier, the existing black ice detection method is expected to present a prevention measure using light [10,15], as a methodology using light sources is used. This strategy is due to the light reflection feature of black ice, and the image data used in this study also needs to be considered. As confirmed by the analysis results, we have checked that the black ice and snow road appear in the Confusion matrix, and we will explain the cause through the train data of two categories. Figure 7 shows the RGB version of train data, with black ice data showing reflections of light, and snow road data showing snow crystals and slush. However, in this study, because the neural network was designed low due to the limitations of computing and the transformation to GRAYSCALE was carried out (Figure 8), it was di fficult to clearly identify these characteristics, resulting in confusion between the two classes and relatively low black ice accuracy of the test data.

**Figure 7.** RGB version of train data (black ice and snow road); in the case of black ice, it can be seen that it shimmers due to light reflection, and in the case of snow data, snow crystals and slush appear.

**Figure 8.** GRAYSCALE version of train data (black ice and snow road); relative to the data in the previous figure, the reflection of black ice and snow crystals and slush are not clearly identified.
