While vehicle design has a major role to play in the dynamics of active safety, it is even more crucial in the realm of passive safety. A vehicle of sound design achieves two important objectives in an accident:
- Keeping the occupants isolated from impact to the maximum possible extent.
- Allowing them to escape easily to safety.
Passive safety systems comprise several design elements.
i. Crumple zones
A crumple zone refers to a portion of the vehicle that is designed to destruct in order to absorb the maximum impact of a collision. This significantly reduces the amount of impact that gets transferred to the occupants.
The vehicle body is a structure composed of different varieties of steel. The crumple zone is made of softer steel and constitutes the front and rear portion of the vehicle, which typically takes the first hit upon impact. The steel progressively strengthens as one moves inwards, i.e., towards the cabin, which is reinforced to remain intact even during impact.
A well-designed crumple zone plays an essential role in determining the overall safety of the vehicle.
ii. Windshield and glass
While a windshield looks like an ordinary plate of glass that sits between the occupants of a car and the fresh air outside, its importance can never be overstated.
The windshield is a structural component of a vehicle made of laminated glass. The salient feature of laminated glass is that it retains its shape upon impact and does not shatter like conventional glass.
The rear windshield and side window, on the other hand, are made of tempered glass. Tempered glass is designed to shatter into many small blunt shards and is used so that retrieving stuck passengers is simplified by better access.
iii. Reinforced cabins
The main cabin that houses the passengers is the most critical component of the passive safety system. After a collision, a well-built vehicle’s doors will still open and allow the passengers to walk away to safety. A good frame comprises reinforced doors, roof, pillars and high seating window lines. A strong cabin is designed to resist the residual forces that are transferred from the crumple zone and seeks to reduce them by means of safety equipment built into the design.
Some sports cars have unconventional door designs that are aesthetically appealing, but can be dangerous in the case of collisions and rollovers. Such vehicles are often fitted with sensor-actuated explosive charges to blow off the doors in the case of an accident.
iv. Fuel tank position
The position of the fuel tank should be such that any leakage is directed away from the accident area. Accidents can often involve fires or stray sparks that can ignite the fuel, exponentially decreasing the chances of survival in adverse circumstances.
v. Submarining components
The impact of a collision can often push mechanical components, such as the pedals, steering wheel and even powertrain components, such as the engine and transmission shafts, into the cabin, resulting in severe injuries.
Submarining components are designed to slide away from and under the cabin, rather than pierce their way into it, thereby improving safety.