According to the European Commission (EC), approximately 20,400 people lost their lives in road accidents across the European Union last year[1]. Enhancing road safety is a critical challenge, and the EC has set an ambitious target to halve the number of road fatalities by 2030. Achieving this goal requires a comprehensive approach involving numerous initiatives and regulations aimed not only at preventing accidents but also at improving the measures taken during and after such incidents. In this context, passive safety systems, which focus on minimizing harm of unavoidable accidents, are crucial to save lives and minimize injuries for all vehicle occupants.
In this article, we delve into the key factors that contribute to certain vulnerable groups being inadequately protected—or even negatively impacted—by existing passive safety systems. These systems, including seatbelts and airbags, have undoubtedly saved countless lives. According to NHTSA, seatbelts and airbags have saved 375,000 and 50,000 lives respectively just in the United States[2]. However, they still have room for improvement to ensure equal protection for all vehicle occupants. We’ll also explore how in-cabin analysis can help address these challenges, offering insights into current and future solutions for intelligent, adaptive restraint systems.
Beyond uncontrollable factors such as the crash direction or speed, there are certain factors that vulnerable groups have in common which can be anticipated and adjusted for to protect them in the event of a crash. Those factors can be categorized into two main types: physiological and situational factors.
Physiological Factors
Research indicates that individual occupant characteristics—such as height, weight, gender, and age—play a critical role in determining injury severity during crashes.
Among these, height and weight stand out as the most influential factors, serving as a foundation for understanding other differentiating elements affecting injury outcomes. A study by the Loughborough University indicates that individuals shorter than 165 cm or taller than 180 cm face a higher risk of head injuries compared to those of average height, due to the design of current safety systems[3]. These safety systems have been primarily designed with the average male dummy in mind, causing any variation from this norm to result in potential inadequate protection of the occupants. Similarly, research by Enayatollah et al. found a direct correlation between a higher BMI and an increased risk of injury and mortality in motor vehicle accidents[4]. While occupants with higher BMI have anatomical and physiological variations altering the response of a crash, it has also been found in the same study that seatbelt usage is less common due to increased discomfort.
These findings suggest that the fact that women are more likely to sustain serious injuries requiring hospitalization[5] stems in part from an on-average height and weight difference between men and women. In addition, men and women have different body compositions which influences the type of injuries and injury severity as indicated in the research of Zhu et al. analyzing men and women with lower and higher BMIs[6].
Similarly, height and weight differences influence age related injury outcomes. Children, including infants, are particularly vulnerable[7]. This stems from their respective differences with regards to the average “dummy sizes”, for instance due to their smaller stature, children are more prone to chest and back injuries. As for elderly individuals, age-related declines in reflexes, sensory perception, and bone density contribute to their increased risk of serious injuries and longer recovery times[8].
All in all, physiological factors play a significant role in how occupants are affected during a crash. Several studies indicate that on average females, children and elderly experience a higher rate of airbag injuries compared to younger, “average”-sized individuals[9]. One reason behind this is that airbags are typically designed based on standardized crash test dummies, which do not reflect the diversity of real-world occupants.[10] Beyond not being able to offer the same level of protection, in some cases, it has even caused additional harm depending on the occupant’s body metrics and positioning at the time of deployment.
Situational Factors
Another type of factors affecting the severity of injuries are situational factors such as the occupants’ body positioning during a crash. In such situations when the occupant is out of position, it is critical to identify and alert the occupant to prevent those undesirable behaviors. In addition, the detection of such situations may lead to the suppression of airbags to avoid significant injuries resulting from its deployment.
Some examples of these include feet on dashboard, leaning forward and submarining which can result from a strongly reclined sitting position. These are improper body positionings which would be highly dangerous in the event of a crash as vehicle safety systems are designed to protect passengers in the proper position. For instance, feet on dashboard can lead to lower body injuries while submarining [11] and leaning forward lead to more head, neck and upper extremity injuries.[12]
Solutions
These findings emphasize the need for vehicle safety systems that can adapt to the diverse body characteristics and body positions of all occupants. While certain aspects of a crash—such as the point of impact and speed—are beyond our control, advances in passive safety systems, enhanced by in-cabin monitoring technologies, can reduce the severity of injuries.
E3D as a specialized company for in-cabin analysis can contribute to intelligent, adaptive restraint control systems. It is within our domain to identify body metrics such as height and weight and the positionings of occupants within the vehicle. Based on this information, passive safety systems can perform real-time adjustments of the airbag deployment strategy, thereby saving lives and mitigating the severity of injuries.
One notable innovation in this field is the smart-RCS project, developed by emotion3D in collaboration with Veoneer and AVL[13]. This system based on a ToF camera represents the world’s first personalized restraint control system, offering tailored airbag deployment strategies to minimize injury and enhance safety for all occupants. With more stringent passive safety regulations on the horizon, such advancements will play a key role in achieving the ultimate goal of protecting every vehicle occupant, regardless of their physical attributes. Euro NCAPs recent announcement of their test protocols for 2026 is a strong and positive push in the right direction.[14]
emotion3D has worked on ways to help generalize this technology by adapting it to 2D cameras which are more commonly used in the automotive in-cabin environment. By combining multiple safety aspects within a single camera system, these can become widely applicable for more vehicles on roads.
Conclusion and Outlook
In conclusion, a variety of occupant-specific factors – including height, and weight, age and gender – influence the risk and severity of injuries in vehicle accidents. To ensure equitable safety for everyone, it is essential that the relevant factors are considered in the design and deployment of passive safety technologies. The wide application of such systems is only possible through the collaborative efforts of both the industry and regulatory bodies. By continuously innovating and refining these systems, the automotive industry move closer to the vision of safer roads and fewer fatalities.