Passenger safety - just bag it!

Vehicle seatbelts save lives. They continue to be the most significant, primary protection feature that saves the vehicle's occupants in the event of an accident, improving their chance of survival by 50 per cent. However, airbags, which are also called supplemental restraint systems (SRS), also dramatically improve the protection offered to the passengers in a car, though these are most effective only when used along with the seatbelts. Airbags save lives and protect occupants from injuring themselves during a collision by offering both a cushion of air to crash into and also act as a force that is in an opposing direction to that of the direction of travel for the occupant. That effectively neutralizes the powerful forward thrust that is created, for example, during a head-on-collision.

Airbags literally explode

An airbag needs to be deployed quickly, actually within fractions of a second, to be fully inflated and effective in cushioning the impact of a collision. However, with an explosive filling out of the airbag, the speed with which it opens is an astonishing 320 kph. Airbags also quickly deflate after the event with the help of perforations at the sides, an important feature that avoids choking the very passengers that it helped save. Despite these features, regular SRS airbags have also been fatal in some cases due to the explosive force with which they deploy. There are a number of registered cases in which children and small made adults have been killed by airbag-related incidents, where the severity of the impact was low and the airbag blew up into the face of the passenger.

What is a dual stage airbag?

The answer to this problem is the dual stage airbag or smart airbag as it is also called sometimes. These are advanced technology airbags that use a combination of sensors and twin inflator modules to vary the level of inflation of the airbag based on the severity of impact or sometimes even the weight of the passenger. Smart airbags or dual threshold or dual deploy airbags actually have a two-stage deployment process built into an electronic control module that is also connected to sensors in the seat cushion (for weight) and into the seatbelts for detecting severity of impact. If the weight of the person seated inside the car is lower than the average or if the person has a small physique, then the electronic circuitry, with the help of sensors, triggers the airbag deployment only up to the first stage, which in most cases will be airbag inflation to the extent of 70 per cent. This lower first stage deployment of airbags would also be triggered if the collision were less severe. In the event of a serious, high-impact collision, the airbag is deployed to its fullest extent enabling it to offer the maximum protection to the car's occupants. At the same time, in the event of an accident, the safety seatbelt makes a contribution. At the instant of the car's impact, the pre-tensioner eliminates all slack in the belt. In the same sequence, the belt then gives a little in order to restrain the occupant gently before the airbag takes over to complete the safety process. Dual stage airbags are usually offered only in the front airbags for the driver (installed in the steering wheel) and for the front passenger (installed in the dashboard panel).S. MURALIDHAR

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