## 1 Introduction
[19] studied drivers' hand positions in a driving simulator during a demanding motorway-merge task, enabling full steering-wheel visibility. Hand positions were classified into three control levels: high, medium, and low. Various traffic conditions were compared, revealing limited differences and no correlation with perceived risk or self-reported mental effort. However, shifts in hand position were linked to changes in workload demand. It is therefore concluded that hand position can provide insight into mental workload. Moreover, a validated simulation model was developed by [PERSON] et al. [23] to analyze vehicle-steering system interaction for on-center handling. Key parameters were altered to assess their effect on steering torque, steering feel, and understeer. Results emphasize the importance of an accurate steering system model. Improvements to center feel include a stiffer torsion bar, higher cornering stiffness, or lower steering ratio, although increasing trail worsens response. Steering rack friction mainly degrades response and column friction reduces center feel, while a stiffer torsion bar lessens understeer tendency. Furthermore, prolonged vibration exposure contributes to muscle fatigue and may compromise driver spinal health [24, 25]. [PERSON] et al. [9] investigated whether reducing whole-body vibration (WBV) affects driver vigilance and discomfort. A crossover design with five truck drivers compared active and passive suspension seats during 10 h shifts. WBV exposure, discomfort, and reaction times were assessed pre- and post-shift. Active suspension significantly reduced WBV, lower back and forearm discomfort, and reaction time deterioration. Also, surface electromyography (EMG) was used in the study developed by [PERSON] et al. [8] to analyze the effects of whole-body vibration (WBV) on trunk and neck muscle activity under varying peak-to-peak displacements and knee angles. Twenty-eight healthy adults performed static squat exercises on a vibration platform. WBV significantly increased muscle activation, particularly in the back. Displacement and vibration conditions were statistically significant factors. These results contribute to optimizing safe and effective WBV protocols for upper-body training. Furthermore, [PERSON] et al. [26] assessed whole-body vibration (WBV) exposure in two types of urban buses: a high-floor coach and a low-floor city bus. Both vehicles were driven along a standardized test route including new and deteriorated highways, city streets, and speed bump segments. Vibrations were measured following [27] ISO 2631-1 and [28] 2631-5 standards. The high-floor bus showed greater WBV exposure, particularly on speed bump sections. Additionally, the seats provided minimal vibration attenuation, highlighting the need to improve seat design and suspension systems. In this context, the redesign of heavy-duty truck cabins must consider the current anthropometric differences of drivers in Ecuador, as these directly influence fatigue and driving ergonomics. Therefore, this study investigates how three technical factors--steering wheel tilt, torque, and cabin vibration frequency--affect driver posture in order to propose minor adjustments to enhance ergonomic performance for drivers in this transport sector in Ecuador.