# Automated Trucks' Impact on pavement Fatigue Damage
## 1 Introduction
This study showed that in the case of implementing a zero-wander mode for ATs, the variations in total rutting depth across different lane widths are more pronounced at lower penetration rates as opposed to higher penetration rates, which is contrary to what is observed when using a uniform-wander mode. Nevertheless, to the best of our knowledge, the lane width effect on pavement fatigue damage for different ATs' wander modes has not been investigated in the literature. In addition, the characteristics of the flexible pavement structure (e.g., layers' thickness and stiffness) could contribute to the structural response of pavement under various wander modes and consequently affect pavement fatigue performance. In this regard, [PERSON] and [PERSON] [8] showed that using normal, uniform, and Laplace distributions instead of zero distribution could result in a reduction in fatigue cracking (FC) of hot mix asphalt (HMA). They indicated that the FC reduction varies with the thickness and stiffness of the material. Specifically, their findings demonstrated that for every 2-centimetre increase in HMA thickness, the FC reduction decreases by 5% to 6%. In contrast, an increase of 1000 MPa in HMA stiffness has a minor effect, with the decrease in FC reduction ranging from 1% to 2.2% [8]. They employed the methodology proposed in the mechanistic-empirical pavement design guide (MEPDG), developed by [PERSON] and [PERSON] [30], to account for the wheel wander effect. However, as [PERSON] et al. [31] pointed out, this approach may produce inaccurate results due to its discretisation of the wheel frequency distribution into only five segments. Furthermore, the effects of market penetration rate and lane width were not considered in the mentioned study. Despite the studies discussed above, there is still a limited understanding of ATs' impact on pavement fatigue performance. Thus, this research aims to enhance the current knowledge by considering the effects of lane distribution scenarios, ATs' market penetration rate, lane width, pavement layers' thickness, and material stiffness concerning ATs' wander mode effect on pavement fatigue damage. Research Problem Statement and Research Objectives  
As discussed above, significant technological advances in ATs offer potential benefits such as reduced energy consumption, pollution, driver stress, and congestion costs, along with increased highway capacity, safety, green mobility, efficient freight transportation, and the feasibility of alternative fuel vehicles [32; 33; 34]. However, a crucial gap exists in understanding the differential impacts of ATs and HDTs on pavement structures. This gap arises from the lack of comprehensive studies comparing the long-term effects of these vehicle types on pavement performance, which is essential for designing pavements that can effectively support both types of vehicles. ATs can follow pre-programmed wandering patterns, ranging from no-wander to normal and uniform-wander modes. While some research has been initiated on how these patterns affect pavement damage, significant gaps remain in understanding how these wandering algorithms influence pavement fatigue performance under various deployment scenarios. As ATs increasingly populate roads, they will coexist with HDTs, leading to mixed traffic conditions. The current understanding of integrating ATs with different market penetration rates and wandering patterns and their impacts on pavement life in mixed-traffic scenarios is limited. Moreover, controlled wandering systems of ATs allow for the possibility of narrower lanes, potentially resulting in significant construction and maintenance savings. However, the impact of lane width on pavement performance, particularly under different AT penetration rates and wander modes, is not well-documented. Research must determine how these factors interact to influence fatigue damage.