## 4 Discussion  
LDW assistance systems are designed to improve road safety by prompting drivers with real-time vehicle motion state information. Currently, studies based on driving simulators have mainly focused on lane departure state recognition. These studies contributed  
Figure 8: Acceptance ratings distribution of LDW system for three styles of drivers engaged in various levels of STs: (**a**) no-distraction and low-level STs; (**b**) low-level and medium-level STs. to valuable experience and data for the design and promotion of LDW systems. However, only a few studies have explored the interactions among driving style, distraction state, and warning timing. This study aimed to explore how various potential factors influence the utility of LDW systems, and to improve the effectiveness and acceptance of LDW systems. The results revealed that drivers with LDW systems had less severe lane departures than drivers without LDW systems, as measured by the shortened duration of lane departure. This finding is consistent with previous research [37]. Previous studies have demonstrated that driving styles significantly affected the drivers' subjective evaluation for warning systems in mixed traffic environments [38; 39]. This study also obtained similar results: the effectiveness of lane departure warning system varied with the driver's distraction state and their driving style. In the undistracted state, both early and late warnings decreased the severity for cautious and moderate drivers relative to the no warning situation, while only late warning had a positive effect on reducing the level of lane departure for aggressive drivers. Note that the subjective acceptance of drivers with all styles in this state were low for these two warning timings. This finding is consistent with reality, as undisturbed drivers can perceive lane departure risk in time, and premature warnings would thus increase resistance instead [40]. When they receive unnecessary warnings, the feedback from drivers is negative [41]. In this case, late warning may be more applicable for drivers with various styles, and it can give the driver more time to react. In other words, when the drivers are undistracted, warnings are less effective and even increased the driver's workload. This study stated that LDW systems are most effective when drivers are distracted [4]. We also found that both early and late warning can effectively suppress the lane departure severity for all types of drivers in a distracted state. The data in this study indicate that, in terms of moderate and aggressive drivers, late warning reduced the severity of lane departure more significantly in the low-level distracted state, and early warning shortened the duration of lane departure more in high-level distracted state. It is worth noting that early warning is more suitable for moderate drivers in medium-level distraction state, while late warning is more suitable for aggressive drivers in this state. This is consistent with the feedback from drivers in the questionnaire survey. One possible hypothesis is that aggressive drivers have a higher risk acceptance, and some lane departure situations may not be considered \"emergency\" events by the aggressive drivers themselves. In this case, the late warning timing is more suitable for aggressive drivers. This is also consistent with the data from [42], who found that LDW systems were more effective in situations where drivers perceive higher risks. These results can help explain the disuse of LDW systems observed in several studies [43]. For cautious drivers, the warning utility and subjective acceptance tend to be consistent only under the high-level distraction condition, and they showed obvious difference under the low- and medium-level distraction conditions. For example, late warning reduced lane departure duration more significantly than early warning for this type of drivers in low-level distraction state, while the subjective acceptance in this situation was higher for early warning.