# Design of Unmanned Road Widths in Open-Pit Mines Based on Offset Reaction Times
## 4 Discussion
### Road Design  
This paper has addressed the specific context of a driverless open-pit mine road relating to two main elements--the lane width and the lateral safety distance. In Section 2.1  
Figure 8: South slope stability analysis: (**a**) original slope; (**b**) optimized slope. Green indicates sandstone beds, purple marks mudstone beds, and gray-black indicates coal beds. Green striped half arcs indicate sliding surfaces.  
of this paper, it was mentioned that lane widths need to be referenced to the width of the largest trucks used in an open-pit mine, while safety distances are generally determined empirically by experts. [PERSON] et al. focused on a case study in Beijing. The authors analyzed the relationships between the lane width and various factors, including the saturation flow rate, lateral safety distance, traffic crash rate, and driver comfort, utilizing data from over 3000 existing crossroads and detailed surveys at seven intersections with varying lane widths. The study employed the Delphi method to evaluate the index weights of design-related factors, concluding that the lateral safety distance is the most critical factor in lane width design [24]. Therefore, for lateral safety distances, this paper investigated the differences in lateral deviation distances occurring in manned and driverless trucks based on differences in driver and sensor reaction times and identified the road widths that can be reduced.  
According to our research, the lateral safety distance for a truck to travel on a road is determined by objectively assessing the lateral offset distance during travel. The width of a road used for transportation in open-pit mines depends on the truck size, terrain conditions, transport operations, safety, efficiency, and other factors. The optimal road width for safe truck operation requires the careful consideration of various factors. This includes the distance and safety clearance between two passing vehicles, as well as the driver's reaction time and speed. As a result, we derived an equation to estimate the maximum lateral offset distance based on the offset angle and speed at which the truck is travelling. [PERSON] et al. investigated how the lane width, shoulder width, and road cross-sectional reallocation affect the driver's lateral positioning, lateral position variability, and driving speed [25]. They found that reductions in lane width caused drivers to drive their vehicles in the center of more advanced roads. However, driverless cars have no such worries.  
When discussing road width design, it is important to note that this paper differs from other studies in that optimizing road widths for open-pit mines can be economically beneficial, while optimizing urban road widths can be costly. [PERSON] et al. focused on how the optimal balance between vehicle lane widths and pavement widths on roads in urban areas can minimize the safety and construction costs [26]. The research incorporated both safety costs and agency costs to determine the optimal road space allocation and evaluated how different weightings of these costs impact the optimal allocation of lane and footpath widths. In contrast, roads in open-pit mines are constantly changing and there are many coal resources under such roads. If the road width can be reduced, the coal underneath the road can be recovered, generating economic benefits.