# A Review of Seatbelt Technologies and Their Role in Vehicle Safety
## 4 Effectiveness, Challenges, and Limitations of Seatbelt Technologies
In the event of an accident, decisions made by AI, like whether or not to tighten the seatbelt more aggressively, may need to be transparent and aligned with the well-being of the passengers. In Table 4, a comparative overview of the features of the seatbelt mechanism is presented. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Feature** & **Retractor** & **Pretensioner** & **Load Limiter** & **Adaptive Seatbelt** \\ \hline \multirow{3}{*}{Function} & Allows & \multirow{3}{*}{Tighters belt instantly to remove slack during deceleration} & Gradually allows belt to remove slack during a crash & Continuously adjusts belt & \\  & & & & \\ \hline \multirow{3}{*}{Activation} & Mechanical (inertia) or & \multirow{3}{*}{Pyrotechnic charge or electric motor} & Mechanical (torsion bar) & Sensor fusion (vision, radar, occupant sensors) and AI & \\  & & & & \\ \hline \multirow{3}{*}{Primary Benefit} & Prevents belt slack & \multirow{3}{*}{Minimizes occupant movement early in a crash} & Reduces chest injuries during belt loading & \multirow{3}{*}{\begin{tabular}{} \end{tabular} } \\  & & & & \\ \hline \multirow{3}{*}{Response Time} & \multirow{3}{*}{Fast (milliseconds)} & \multirow{3}{*}{Instant (milliseconds)} & Gradual, during sustained force & Continuous; proactive and real-time tension modulation \\ \hline \multirow{3}{*}{\begin{tabular}{} \end{tabular} } & Upon rapid & At initial crash & After pretensioner activates and load builds & Pre-crash phase through \\  & & deceleration or rollover & detection & activates and load builds & post-impact, anticipatory and adaptive throughout \\ \hline \multirow{3}{*}{Reusability} & \multirow{3}{*}{Reusable} & Single-use; must be & Typically durable, no & Reusable; designed for continuous operation without mechanical \\  & & & & \\ \cline{1-1}  & & & & \\ \hline \multirow{3}{*}{Cost} & \multirow{3}{*}{Low to moderate} & Higher due to complex components & Moderate to high if & High; includes advanced \\  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \hline \multirow{3}{*}{Limitations} & \multirow{3}{*}{\
\begin{tabular}{} \end{tabular} } & One-time use; no load & Limited benefits in & Complex integration; reliant \\  & before locking & management & low-speed impacts & on accurate sensing and \\ \cline{1-1}  & & & & \\ \hline \multirow{3}{*}{
\begin{tabular}{} \end{tabular} } & \multirow{3}{*}{Standard in all vehicles} & Common in front-seat systems of modern vehicles with advanced restraint systems & Common in modern & Emerging in high-end or \\  & & & & & \\ \cline{1-1}  & & & & & \\ \hline \end{tabular}
\end{table} 
Table 4: Seatbelt mechanism comparative table. This critical evaluation underscores the need to balance technological sophistication with user behavior, system reliability, and real-world variability in crash scenarios. While each innovation adds a layer of protection, no system is infallible without correct usage and contextual effectiveness. In Table 5, a comparative overview of seatbelt technologies and injury outcomes by passenger group is presented. Seatbelt technology has significantly advanced beyond the traditional three-point design, offering improved occupant safety through innovative features. The standard three-point seatbelt is simple, reliable, and cost-effective, and it has been shown to reduce fatal injuries by 45-60% in crashes [139; 140]. Advantages of this system include its proven life-saving ability and widespread global acceptance. However, disadvantages are notable: it offers limited protection in non-frontal collisions, does not adapt to occupant size or crash severity, and, if improperly adjusted, can cause injuries such as rib fractures. To overcome some of these shortcomings, pretensioners and load limiters were introduced. Pre-tensioners remove slack instantly during a crash, while load limiters prevent excessive forces on the chest. These systems can lower injury severity by up to 20-25% [29; 141; 142].