# A Review of Seatbelt Technologies and Their Role in Vehicle Safety
## 1 Introduction  
The seatbelt assembly is one of the base components of vehicle safety [1], having saved countless lives since its introduction. Over time, seatbelt technologies have evolved, driven by advances in automotive engineering, mechanical design, materials science, sensors, electronics, medical research, crash safety studies, and regulatory requirements. The importance of seatbelt's in protecting vehicle occupants during collisions cannot be overstated, as they serve to restrain the body and minimize the risk of serious injury [2, 3]. Traditionally, seatbelt's were designed to prevent occupant ejection and limit harmful movements during a crash [4], forming the cornerstone of passive vehicle safety systems. Recent decades have seen significant innovations in seatbelt technologies to improve both comfort and protection. Mechanisms such as retractors, which allow the seatbelt webbing to extend and retract automatically, have improved usability and ensured proper belt positioning. The development of pretensioners, which rapidly tighten the belt duringa collision, and load limiters, which control the force exerted on an occupant's chest by allowing slight belt extension, have further optimized occupant protection by minimizing injury risks during high-impact events. These advancements have progressively improved the effectiveness of seatbelt systems in modern vehicles. As the automotive industry transitions toward greater automation, new challenges emerge for occupant safety systems. With the advent of intelligent vehicle technologies and autonomous driving, seatbelt designs must evolve to address scenarios where human drivers may no longer be actively controlling the vehicle [5; 6]. Active seatbelt systems, capable of adjusting belt tension dynamically based on crash severity, are increasingly critical for mitigating crash forces and enhancing occupant protection. Moreover, seatbelt systems are now integrated into a broader active safety ecosystem that includes automatic braking, lane-keeping assistance, and collision avoidance technologies. In this context, seatbelts not only serve as passive restraints but also operate in concert with proactive systems to ensure comprehensive occupant safety in both conventional and autonomous driving environments [7; 8]. In Figure 1, the seatbelt innovation roadmap is presented as a timeline from early development to emerging technologies. In Figure 2, the conceptual overview of seatbelt technology is presented, in terms of traditional seatbelt, integrated seatbelt, and advanced seatbelt system. Despite the substantial advancements in seatbelt design and the growing body of research on occupant protection, several gaps remain in the literature. For example, there is limited empirical evidence on how active seatbelt systems perform across diverse passenger populations, particularly in non-standard seating configurations anticipated in autonomous vehicles. Moreover, existing studies often treat occupants as a homogenous group, overlooking physiological and biomechanical differences related to age, pregnancy, or size. These gaps highlight the need for a comprehensive review that not only synthesizes technological developments but also evaluates their effectiveness across varied user contexts and future mobility scenarios. This narrative review aims to provide an overview of the latest seatbelt technologies, examining the integration of traditional and modern seatbelt technologies, with particular attention to passenger-specific adaptations and the evolving role of seatbelts in autonomous vehicles. By exploring seatbelt mechanisms such as retractors, load limiters, and pretensors, as well as their role in active safety systems, we aim to highlight how these innovations are helping to reduce injuries and fatalities on the road. Also, by exploring the intersection between traditional restraint systems and emerging technologies, we hope to provide valuable insights into ongoing advances in vehicle safety and their implications for the future of transportation.