# A Review of Seatbelt Technologies and Their Role in Vehicle Safety
## 3 Results
### Interconnection of Active and Passive Safety Systems
It demonstrates how integrating systems like ESP with airbags and seatbelt tensioners enhances occupant safety, the focus being placed on side crashes and rollovers, where timing and coordination are important. Various side impact scenarios in which active safety systems and seatbelt are interconnected were simulated in [46]. The studied collisions between a vehicle and a mobile barrier were created using HyperMesh software ([[https://altair.com/hypermesh/](https://altair.com/hypermesh/)]([https://altair.com/hypermesh/](https://altair.com/hypermesh/)), accessed on 5 May 2025) and had varying collision angles. The simulations modeled the seatbels, side airbags, and curtain airbags. The AEB brake was performed with different intensities in the simulations. The study showed that the use of active seatbels, with an immediate pre-pretensioning (at 0 ms) of 80 N, reduced the weighted injury criterion by 5.94%, 22.05%, and 20.37% at impact angles of 90\({}^{\circ}\), 105\({}^{\circ}\), and 120\({}^{\circ}\), compared to conventional seatbels. The authors in [47] studied oblique collisions in vehicles equipped with AEB systems and pre-pretensioner seatbels. In the pre-collision phase, AEB activation leads to an out-ofposition (OOP) posture of the driver, with increased head and chest displacements, in the case of belts without a pre-tensioner. Active belts significantly reduce these displacements. They preventively restrain the occupant during the pre-collision phase, reducing forward movement and the risk of being OOP. The research results emphasize the need to optimize the airbag activation time depending on the parameters of the active seatbelt in order to maximize the effectiveness of protecting vehicle occupants. In [48], the authors studied the behavior of two types of belts on injuries to the occupants. During the pre-crash phase, head, first thoracic vertebra, and first lumbar vertebra displacements were greater with the B-pillar-integrated (BPI) seatbelt than with the Belt-in-seat (BIS), mainly due to the lack of initial contact between the torso and the seatbelt. Pelvis pre-crash displacements, however, remained consistent across seatbelt types. In the in-crash phase, variations in shoulder belt forces were directly influenced by the different load-limiting levels of the shoulder belt. The risks of traumatic brain and rib fractures were amplified with BPI seatblets, especially at higher load-limiting force. However, the BPI design demonstrated reduced lumbar spine fracture risks (from 30% to 1%). Autonomous driving technology allows occupants to adopt more comfortable positions, which include a pronounced reclining of the seatbacks [49]. The results indicated that occupants were more prone to submarining and the failure of seatbelt restraints. Conventional restraint systems fail to sufficiently limit the forward movement of occupants during a collision. In the study, the authors used HyperMesh software to model the vehicle and frontal collisions, PRIMER and HyperMesh for airbag and seatbelt, and the Total Human Model for Safety (THUMS) human model to simulate the occupant response and assess injuries. The study concludes that a restraint strategy that combines a larger volume airbag with a special \"knee booster\" support for the knees improves protection for occupants in a reclining position during a frontal collision. These findings may contribute to the design of safety systems for autonomous vehicles. Further on, the authors in [50] found that some of the factors impacting the choice of wearing a seatbelt include gender, road classification, weather condition, vehicle types, time of driving, vehicle registration, and day of the week. Reference [51] indicates that females in general are more inclined to be buckled. In [52], it is said that safety belt reminder systems appear to be effective for the general population. The authors highlight some conclusions, below mentioned.