weight is a mass in the packaging system. The natural frequency of the packaging system can be calculated using the following equation (Equation (1)):  
\[f_{n}=\frac{1}{2\pi}\sqrt{\frac{kg}{W}} \tag{1}\]  
where \(f_{n}\) is natural frequency (Hz), \(k\) is spring constant, \(g\) is gravitational acceleration, and \(W\) is product weight. This equation indicates that a packaging system's resonance depends on the cushioning material's spring constant and the system's weight. The ratio of the natural frequency of the system and the frequency of the input vibration (vibration generated from the package delivery vehicle in this case) determines whether the acceleration or amplitude of the product-package system will be greater (amplification) or lower (attenuation) than that of the input vibration. This phenomenon is called transmissibility. Transmissibility increases when the packaging system's natural frequency overlaps or gets close to the frequency of the input vibrations. Therefore, packaging engineers need to avoid designing packaging systems with a natural frequency close to the peak intensity frequency of the targeted distribution environment. According to the previous explanation, packages designed to have natural frequencies that are far from the peak acceleration frequencies of international testing standards' vibration test profiles can become less effective in different geographical regions. This is because other countries could use various types of package distribution vehicles, which have peak intensity frequencies closer to the initially designed natural frequency of the packaging system. The amplified vibration level due to matching frequencies can cause more fatigue and potential scuffing to the product. Many researchers in the past have observed and analyzed the country-specific characteristics of shock and drop events and vibration levels needed to update international testing standards to be suitable for their regions. Characteristics of shock and drop events have been investigated in Europe [4], China [5], the United States [6; 7; 8], South Korea (Korea) [9], and transcontinental parcel shipments between Europe and the United States [10]. The vibration levels of heavy, large trucks, commonly used as first-echelon vehicles in the parcel delivery industry, were also widely researched for different regions, such as India [11], Japan [12], Spain [13], the United States [14], China [15], and Korea [16]. The vibration levels of other modes of transportation for packaging, such as drones [17], industrial forklifts [18], multimodal shipping containers [19], ULD dollies at air cargo sorting hubs [20], and aircraft [21], and how vibration is generated by these different modes of transportation can affect the integrity of packaged products [22; 23; 24; 25]. This has also already been widely investigated. However, the vibration levels of second-echelon vehicles used for last-mile paler delivery have only been measured in a few countries, such as Australia [26], Hungary [27], the United States [28; 29], China [30], and Southeast Asia [31]. Packaging engineers have decades of experience designing packages for large trailers; hence, they understand the vibration environment very well through multiple studies published in different countries [11; 12; 13; 14; 15; 16]. Yet, there is a growing need to understand the last-mile delivery portion of the distribution environment, which is conducted using smaller vehicles, due to its severe harshness compared to the larger truckload environment. The ISTA 3A recommended vibration test profile for last-mile delivery vehicles [2] has 75% higher intensity at the peak frequency band than the main peak in the first echelon vehicle vibration simulation profiles. Also, there are many changes in last-mile delivery vehicles that happen due to the different strategies of various business models, the different urban structures of various countries, and the advent of technologies, such as electric vehicles.