PURPOSES : The purpose of this study is to evaluate the road design elements affecting the lateral driving safety under high-speed driving conditions with a speed limit of 140 km/h and to derive useful implications to design of safer roads. METHODS : A full-scale driving simulator was used to evaluate the various design scenarios. Different regression techniques and a random forest method were adopted to conduct comprehensive comparisons among the simulation scenarios. The relationships between the safety indicators, including the frequency of the lane departures and the standard deviation of the lateral acceleration, and the design elements were explored in terms of lateral driving safety. RESULTS : The length of the combined alignment was found to be a significant factor affecting the lateral driving safety based on the analysis of the frequency of lane departures. Regarding the standard deviation of the lateral acceleration, it was identified that the length of the horizontal curve, the length of the bridge, and the right-side superelevation must be considered significant factors associated with driving safety while designing the road under high-speed driving conditions. CONCLUSIONS : Based on the findings of this study, a set of recommendations for designing roads was proposed. For example, the proper length of the combined alignment and the horizontal curve should be determined to prevent crashes due to hazardous lateral driving events because the installation of sufficient superelevation in the bridge section would be limited under high-speed driving conditions. In addition, applying a larger horizontal curve radius with longitudinal grooving is a promising approach to tackle risky driving conditions.