## 2 Literature Review  
In this section, we discuss the findings from previous research reviews that highlight factors potentially affecting motorcycle crash severity among young adult motorcyclists (YAMs) and explore the differences between urban and rural roads. One frequently identified significant factor is the gender of the driver. Many studies have found that male drivers, especially young males, are more prone to crash fatalities than females [13]. Another variable that may play a role is the presence of foreign drivers. In developing countries, a substantial number of tourists are allowed to rent motorcycles. However, their unfamiliarity with local laws, speed limits, and traffic conditions could influence crash severity [7]. An at-fault rider signifies the cause of a crash in such instances. While previous research has investigated this issue, the results have been inconsistent, with  
Figure 2: Local roadways in urban and rural areas. Source: Google maps. (**a**) Local roadway in an urban area (coordinates: 14.974957769842616, 102.0974113396429), (**b**) Local roadway in a rural area (coordinates: 14.977037204559815, 102.09087001080657). most findings deemed insignificant. [PERSON] and [PERSON] [19] argued that if the motorcyclist is at fault, the likelihood of fatality increases. A local address pertains to drivers who are from the same district and are highly familiar with the roads, especially in urban settings, where they are aware of stopping points and intersections. This contrasts with drivers from other areas [10]. Helmet use is a well-established factor that can decrease the risk of death, regardless of a rider's age or location [20]. A crucial consideration for YAMs is possessing a driver's license, which demonstrates that they have undergone training and testing, resulting in the learning of vital skills for preventing and minimizing crash severity [21]. The hypothetical cause of an incident can lead to varying degrees of severity. For instance, using excessive speed directly impacts the force of a collision, consequently increasing the chances of fatality. The differences between urban and rural roads in terms of traffic conditions may influence drivers to drive at higher speeds. While rural roads have less traffic, drivers are more likely to drive faster on urban roads [22]. Another significant factor is suddenly cutting in front of other vehicles. In cases where vehicles are of the same type, the impact may be less severe, particularly on low-speed roads such as urban streets [23]. The physical characteristics of roads often influence driving performance, with crashes frequently occurring on straight roads, especially those outside cities. This can increase the likelihood of fatal motorcycle crashes [24]. Local roads tend to be of a lower standard than highways and may have damaged pavement, which can greatly affect smaller vehicles like motorcycles. This issue might also be connected to familiarity with the route [25]. Environmental factors can significantly impact driving, particularly for less experienced riders like YAMs. Variables, such as riding in the rain, can affect driving behavior. Most motorcyclists tend to drive slowly in the rain and may even stop, resuming their ride once the rain has stopped. As a result, the correlation with severity could be negative [6]. Driving in low visibility conditions, like in dust or fog, is often associated with driving in the rain due to a driver's hesitance to use high speeds [10]. Nighttime driving, which includes crashes with and without lights, can lead to higher severity. Clearer roads at night may encourage higher speeds, while low visibility can make it difficult to see warning signs or parked vehicles on the road shoulder, increasing the risk of severe crashes compared to daytime driving [15]. An in-depth analysis of the literature reveals various factors that have been identified as critical in influencing the severity of injuries sustained in motorcycle accidents.