# Lateral Oscillation Characteristics of Vehicle Trajectories on the Straight Sections of Freeways
###### Abstract  
The lateral oscillations of vehicle trajectories are a significant cause of collisions. There is a dearth of research, however, on the oscillatory behaviors of vehicles driving on straight sections of freeways. This study aimed to investigate the effects of vehicle type, lane position, and speed on oscillation behavior and to propose quantitative indicators to explain lateral oscillation characteristics. Based on these characteristics, a more appropriate lane width can be determined. First, the k-means algorithm was performed to cluster the vehicles into three categories: passenger cars, medium-large cars, and extra-large trucks. Then, statistical methods such as analysis of variance (ANOVA) and regression analysis were employed to elaborate on the speed distribution, lateral amplitude (LA), and distance traveled within the oscillation cycle (DTOC) for various vehicle types. The results show that different types of vehicles have different lateral oscillation tendencies. The LA and DTOC for passenger cars are generally more extensive than for medium-large cars and extra-large trucks, and their oscillation patterns are the most complicated. The vehicle trajectory oscillation pattern varies significantly for different lane positions and speeds, but speed is the dominant influencing factor. The naturalistic driving dataset from German freeways served as the foundation for this study. These results can assist road engineers in better understanding the behavioral characteristics of vehicle trajectory oscillations and designing safer freeways.  
driving behavior; straight section of freeway; trajectory oscillation; lateral amplitude; lane width; naturalistic driving dataset +
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is adopted, it is crucial to comprehend how lane width changes may affect drivers and passengers, especially in terms of safety. Furthermore, the parameters of lane width for different speeds, lane positions, and vehicle types are not apparent.  
However, most cars still have plenty of room to maneuver with the present width of freeway lanes. The driver has more options to control the car's lateral position on the road so that the vehicle's trajectory appears to oscillate laterally within the lane. The study of vehicles' trajectories while maintaining a lane can thus help with lane design. On the other hand, the characteristics of vehicles' trajectories are also a critical element in studying traffic safety causation and revealing the accident mechanism.  
Accordingly, reasonable lane width optimization is required to increase road capacity without compromising vehicle operating speed and better regulate the stability and safety of cars to decrease the frequency of traffic accidents. The primary goal of this research is to clarify the lateral oscillation characteristics of vehicle trajectories on straight sections of freeways and investigate the factors that influence them. The findings allow for the quantification of the trajectory oscillation behaviors of vehicles on the freeway and the construction of proper lanes based on requirements for traffic safety and driving behaviors.