The Hindu Business Line : Question & Auto

How do airbags work? How many varieties are there? Are all airbags the same and perform similarly — from the ones in a Mercedes Benz to the ones in a Suzuki Swift ZXi? Why aren’t all cars in India fitted with airbags as part of standard fitment, which I feel is a necessity and not a luxury?

Why isn’t the Government giving exemptions for cars fitted with airbags? Multinational car companies are introducing the same global models in India and other countries, only minus the airbags here. Why? — Dr C. Srinivas

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.

This reverse thrust effectively neutralises the powerful forward motion that is created, for example, during a head-on-collision.

An airbag needs to be deployed quickly, actually within fractions of a second, and fully inflated to be 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, but the airbag blew up into the face of the passenger with the same force as happens during a full impact.

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.

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).

So, all airbags are not the same. They may feature a variation of the basic technology and may work in conjunction with more than one sensor.

Airbags are as yet an expensive technology and the cost of a car fitted with just dual airbags can cost as much as 15-20 per cent more than the same model without this addition. Airbags also perform better or offer the most protection during high-speed collisions.

Their effectiveness is much lesser at speeds below 40 kmph. Seat belts can do the job of protecting occupants at slow speeds.

In India, the car buyer is extremely price-conscious and that was the reason why even switching over to multi-point fuel injection (MPFI) from the old carburettor technology took the intervention of the courts to enforce.

With the improvement in the highway network and an increase in road travel, airbags may become indispensable for buyers who appreciate better occupant protection, though it comes at a price.

On the other hand, if the Government or the courts intervene again and make it mandatory for airbags to be provided as part of standard fitment, it will serve a great cause and the price of the technology will also crash.

(Queries may be sent to:q&a@thehindu.co.in or by post to Q&A, Business Line, 859/860, Kasturi Buildings, Anna Salai, Chennai - 600 002.)

S. Muralidhar

More Stories on : Cars | Technology

Article E-Mail :: Comment :: Syndication :: Printer Friendly Page