## 1 Introduction  
Worldwide, there are initiatives and campaigns to improve road access for more vulnerable road users (as stated in Goal 11.2 of the Sustainable Development Goals) [1]. Motorcyclists make up a large portion of vulnerable road users, so motorcycle crashes pose a critical challenge for sustainable development, especially in developing nations (like Thailand, Vietnam, Indonesia, and Malaysia), where motorcycles are widely used [2; 3]. Motorcycle crashes often have a heightened risk of fatalities, whether in single-vehicle crashes or crashes with other vehicles [4]. Thailand is among the countries with the highest prevalence of motorcycle use, with at least one motorbike owned by 87% of households in the nation. Due to the fact that motorcycle accidents on main roads, arterial routes, or highways are associated with high fatality rates [5], comprehensive research has already been conducted on this aspect in Thailand [6]. However, a noteworthy facet of transportation infrastructure that deserves more thorough examination relates to local roads. These roadways witness a significant inflow of motorcycle traffic and, alarmingly, make a substantial contribution to the escalating fatality toll resulting from motorcycle accidents. Notably, between 2015 and 2020, there were a staggering 94,284 reported motorcycle accidents on local roads in Thailand, resulting in 14,495 fatalities [7]. Local roads, typically prioritizing accessibility, often traverse areas like villages and similar communities. Figure 1 serves as a visual representation of the distribution of motorcycle accidents on local roads in Thailand. Upon closer examination, a disconcerting trend manifests where a significant proportion of these accidents predominantly involve motorcyclists under the age of 30, a demographic commonly classified as Young Adult Motorcycle riders (YAM) [8]. The selection of YAM as the focal point of our study finds its rationale in several key considerations. This age group often exudes a heightened level of self-assurance grounded in their physical attributes, which include exceptional vision and overall physical strength. This sense of self-assuredness, in turn, inclines them toward operating their motorcycles at elevated speeds [3]. Moreover, substantiating our choice further, the research findings of [PERSON] et al. [9] expound upon the correlation between possessing a driver's license and amplified self-confidence, particularly among individuals aged 18 to 19 within the YAM demographic. This boost in self-confidence has been observed to lead to the adoption of aggressive driving behaviors, thereby elevating the susceptibility to accidents and subsequent fatalities. Such increased risks materialize in various forms, notably through close-cutting maneuvers and instances of driving under the influence. Therefore, our emphasis on YAMs in this study not only aligns with the observed trend, but also delves into the nuanced dynamics of this demographic's driving behavior, shedding light on the multifaceted aspects contributing to elevated risks and ultimately emphasizing the urgent need for targeted safety policies and interventions in the context of local road safety in Thailand. [PERSON] et al. [10] investigated the severity of motorcycle crashes by comparing younger and older motorcyclists. As displayed in Table 1, many studies have not concentrated on local roads and have seldom been conducted in developing countries. Moreover, no research has analyzed crashes based on spatial instability [11]. Thus, it is clear that the following crucial aspects remain unaddressed: the physical features of the roads, traffic volume, and vehicle types used on local roads. Differences between urban and rural roads may exist. Urban rural roads, delineated by municipalities and characterized by the concentration of primary activities in sub-districts and districts, prioritize access to large activity sites such as shopping malls, stores, and government offices.