Pedestrian Protection System

Pedestrian Protection System is an integral part of modern automotive safety technology, designed to minimise the severity of injury to pedestrians during unavoidable vehicle-pedestrian collisions through active warnings and passive cushioning. With vehicle safety regulations tightening globally, this system has progressively trickled down from luxury marques to mainstream models, establishing itself as a key benchmark in assessing vehicle safety performance.

Driven by National Regulations

The widespread adoption of pedestrian protection technology is intrinsically tied to the push of mandatory regulatory frameworks. China officially implemented its revised mandatory national standard, GB 24550-2024 "Pedestrian Crash Protection for Motor Vehicles", on 1 January 2025. This standard sets out clear technical specifications, test procedures, and assessment criteria for M1 and N1 category vehicles regarding pedestrian crash protection, compelling carmakers to incorporate pedestrian safety as a core design priority right from the vehicle R&D stage.

Core Technology: Passive Protection

When a collision is inevitable, passive protection technology acts directly to mitigate physical trauma, operating primarily across two dimensions: "cushioning" and "energy absorption".

Pop-Up Bonnet Technology (Active Bonnet)

This stands as the most critical passive safety measure today. The system monitors impact signals in real time via pressure sensors integrated inside the front bumper. Once the sensors register pressure profiles characteristic of a human collision (as opposed to hitting an animal or a rigid object), the control unit triggers the pyrotechnic actuators at the rear edge of the bonnet in a split second (around 0.03 seconds), instantly popping up the rear section of the bonnet by a specific height (typically 4 inches or 50 to 65 mm).

This mechanical deployment creates an energy-absorbing crumple clearance between the pedestrian's head or torso and the unyielding engine block underneath. The elevated bonnet acts like an inclined "cushion", effectively cushioning head impact forces while preventing the pedestrian from striking directly against the rigid front windscreen. In the Mercedes-Benz EQS, for instance, the bonnet remains propped up once deployed, requiring the owner to visit an authorised service centre as soon as possible for a system reset.

External Pedestrian Airbag

This represents an advanced evolution of pop-up bonnet technology. In tandem with the bonnet raising, airbags concealed along the lower cowl of the front windscreen or near the A-pillars deploy simultaneously, shielding rigid structural areas that could inflict secondary injuries. Furthermore, some carmakers install airbags within the front bumper to protect the pedestrian's legs and prevent them from being pulled underneath the vehicle. Crash simulation data indicates that with such head-protection airbags fitted, the Head Injury Criterion (HIC) value drops dramatically from 2,123 without airbags to 845, significantly lowering the injury severity level.

Energy-Absorbing Body Structure Design

This serves as a foundational and widely applied passive safety solution. By incorporating energy-absorbing foam, ductile plastics, or specialised collapsible brackets across key contact zones such as the bumper, bonnet, and front fenders, these body panels can progressively deform during an impact to dissipate kinetic energy.

Cutting-Edge Technology: Active Warning

Unlike the aforementioned "post-crash" measures, active warning technology strives to intervene before an impact occurs. Using front-facing cameras and radar sensors to monitor road users ahead in real time, the system alerts the driver via audible and visual warnings the moment a pedestrian is detected with an imminent risk of collision. If the driver fails to respond in time, the system links with the Autonomous Emergency Braking (AEB) function to actively scrub off speed or bring the vehicle to a complete halt. This seamless blend of active and passive systems effectively reduces false triggers and marks a vital pathway for enhancing overall vehicle safety in the future.

All in all, pedestrian protection systems have formed a complete safety chain spanning "pre-crash warning" to "post-crash cushioning", evolving from standalone passive measures toward integrated active protection powered by intelligent perception and decision-making.