# A Review of Seatbelt Technologies and Their Role in Vehicle Safety
## 3 Results
### Interconnection of Active and Passive Safety Systems
The effects of reminders, safety belt use monitoring devices, interlock devices, and improvements in comfort and convenience on teen belt use need to be explored. Interlock systems, such as not allowing the radio or CD player to turn on until all passengers are wearing safety belts, also hold promise and could be very effective in increasing safety belt use, particularly for teenagers. Combinations of strategies seem to work better than one strategy alone. A community program including education, diversity outreach, highly publicized enforcement, and parental involvement would likely have a substantial effect on teen belt use. However, these strategies would probably need to be sustained for the effect to last over time. In [53], it was found that some user safety errors like not using a seatbelt, seatbelt misuse, excessive seat-back reclining, insecure cargo, and a lack of occupant protection in older vehicles resulted in young adults sustaining severe or fatal injuries in cases of collisions. The frequency of seatbelt use was higher among participants from cities with higher socioeconomic status. As a result, it was found that adolescents who exhibited more risky behaviors had a lower frequency of seatbelt use and seatbelt use was associated with socioeconomic level and parental education level [54]. Also, the pre-pretension seatbelt could reduce the occupant's forward movement in the rotating seat positions in a pre-crash period. One of the aims of the study in [55] was to generate an envelope of occupant movement before the crash, which could be beneficial for future restraint systems and vehicle interior design. The authors in [56] studied double pretensioning and its effect on steral deformations. Having experimental tests with two types of Hybrid III and THOR dummies, they found that double pretensioning reduces the deflection of both dummies being higher for THOR. An increased reduction is found in the lower chest area with Hybrid III. THOR shows the highest differences in the upper area. Also, the authors in [57] present an innovative system for detecting vital signs, integrated into the seatbelt, that uses a meta surface radar for non-invasive health monitoring in the car. The system uses a flexible transmit array lens and a Frequency Modulated Continuous Wave (FMCW) radar sensor to accurately detect seatbelt use and positioning through human tissue, monitoring heart rate and respiration. Experimental results demonstrate the potential of this system to improve health monitoring in dynamic vehicle environments. Recent research has moved beyond conceptual discussions by employing simulation-based methodologies and analysis of experimental data to evaluate the integration of active and passive safety systems. For instance, the study Integration of Active and Passive Safety Technologies demonstrates injury risk reductions of 17% and 48% in frontal impacts through the integration of driver assistance systems with passive restraints, using both ATD and human body models [58]. Similarly, Integrated Active and Passive Systems for a Side Impact Scenario applies coupled simulation tools (PreScan and Madymo) to model side impact scenarios, offering quantitative insights into system performance [44]. The CAPS study further supports these findings by showing improved protection in rollovers and side crashes through the coordination of electronic stability programs with seatbelt tensioners and airbags [45]. Another study develops a method combining field data, naturalistic driving data, and simulations to assess injury reduction from integrating passive and active safety systems in frontal impacts. A driver assist (DA) feature aimed at reducing delta-V was analyzed, with field data assuming a 20% crash avoidance rate due to pre-crash braking [59]. The paper by [60] proposes an integrated tool environment comprising Model-in-the-Loop, Software-in-the-Loop, and real-time Hardware-in-the-Loop systems, incorporating crash and vehicle simulations based on real and synthetic data.