Airbag is an essential technology that is popular world over. However, this technology comes at a cost and in India, we still lag miles behind when it comes to the use of this technology with the general population of our country. There are jurisdictions where it is mandatory for the automobile manufacturers to incorporate the essential airbag technology. However, in India, the same is at the discretion of the automobile manufacturers who in turn charge an exorbitant premium to give access to this basic life-saving technology.

This article aims at highlighting the features of the airbag technology, its utility and rationale for availability as a basic feature of an automobile, irrespective of the jurisdiction.

About Airbags
An airbag is a vehicle safety device and is an occupant restraint system. The airbag is designed to inflate extremely rapidly then quickly deflate during a collision or impact with a surface or a rapid sudden deceleration. The package consists of an airbag cushion, a flexible fabric bag, inflation module and impact sensor. The purpose of an airbag is to provide the occupants a soft cushioning and restraint during a crash event to prevent any impact or impact-caused injuries between the flailing occupant and the interior of the vehicle. Depending upon the type of airbag installed in the vehicle, it provides an energy absorbing surface between the vehicle’s occupant and a steering wheel, instrument panel, A-B-C- structural body frame pillars, headliner and windshield/windscreen.[1]

The purpose of an airbag is to slow the passenger’s forward motion as evenly as possible in a fraction of a second. There are three parts to an airbag

  • The bag itself is made of a thin, nylon fabric, which is folded into the steering wheel or dashboard or, more recently, the seat or door.
  • The sensor is the device that tells the bag to inflate. Inflation happens when there is a collision force equal to running into a brick wall at 10 to 15 miles per hour (16 to 24 km per hour). A mechanical switch is flipped when there is a mass shift that closes an electrical contact, telling the sensors that a crash has occurred. The sensors receive information from an accelerometer built into a microchip.
  • The airbag’s inflation system reacts sodium azide (NaN3) with potassium nitrate (KNO3) to produce nitrogen gas. Hot blasts of the nitrogen inflate the airbag.

The functioning of an airbag can be understood from the diagram below[2].

Even though the whole process happens in only one-twenty-fifth of a second, the additional time is enough to help prevent serious injury.
Depending upon the nature of requirement, an airbag module is of the following types:

  • Driver airbag module
  • Passenger airbag module
  • Side curtain airbag module
  • Seat-mounted side impact airbag module
  • Knee bolster airbag module
  • Inflatable seat-belt modules
  • Front Right Side Airbag Sensor
  • Front Left Side Airbag Sensor
  • Pedestrian airbag module

Invention of Airbags
The first commercial designs were introduced in passenger automobiles during the 1970s with limited success. Broad commercial adoption of airbags occurred in many markets during the late 1980s and early 1990s with a driver airbag, and a front passenger airbag as well on some cars; and many modern vehicles now include six or more units.
In the early 1970s, Ford and General Motors began offering cars equipped with airbags, initially in government fleet purchased Chevrolet automobiles. General Motors Oldsmobile Toronado was the first domestic vehicle to include a passenger airbag. The automaker discontinued the option for its 1977 model year, citing lack of consumer interest. Ford and GM then spent years lobbying against air-bag requirements, claiming that the devices were unfeasible and inappropriate. Chrysler made a driver-side airbag standard on 1988–1989 models, but it was not until the early 1990s that airbags became widespread in American cars

Functioning of an Airbag
During a crash event, the vehicle’s crash sensor(s) provide crucial information to the airbag electronic controller unit (ECU), including collision type, angle and severity of impact. Using this information, the airbag electronic controller unit’s crash algorithm determines if the crash event meets the criteria for deployment and triggers various firing circuits to deploy one or more airbag modules within the vehicle. Working as a supplemental restraint system to the vehicle’s seat-belt systems, airbag module deployments are triggered through a pyrotechnic process that is designed to be used once. Newer side-impact airbag modules consist of compressed air cylinders that are triggered in the event of a side on vehicle impact.

After a vehicle collision has been detected, airbags inflate faster than you can blink your eye. Airbags are key components in automotive safety systems, and, although we can see them perform with the naked eye, they soften the impact of collisions by keeping passengers from contacting the steering wheel, dashboard front glass, and other parts of the automobile. So, to explain what airbags actually do when an accident occurs, let´s use an example of a typical head-on collision.[3]

Sensors detect the impact
As the satellite sensors (collision sensors) attached to the vehicle detects the collision, a signal is sent to the ECU (Electronic Control Unit).

Evaluation of the impact
The signal sent from the satellite sensors to the ECU is processed, and the ECU determines the severity of the impact based on inputted data. If the ECU determines that an airbag deployment is necessary, it sends a signal to initiate the airbag inflators (gas emitting devices).

The airbags go into action
The inflators are activated through an igniter, causing a chemical reaction that emits gas, resulting in the deployment of the airbag cushion.

Inflation of the airbags is completed
The force of the collision reaches the passengers, and they begin to move forward. By this time the airbags are fully inflated and they are ready to receive and restrict the movement of the passengers. The inflation of the driver side airbag takes between 20- 30 milliseconds. For the passenger side airbag, it takes between 30-40 milliseconds.

Passenger motion energy is absorbed
By this time, the airbags are fully inflated. The motion energy of the passengers are absorbed by the crushing of the vehicle, the seat belt load limiter, and the airbags.

Passenger motion energy is fully absorbed
The energy of passenger movement is fully absorbed.

Challenges with Usage of Airbags

  • Lack of re-usabilityA chemical reaction produces a burst of nitrogen to inflate the bag. Once an airbag deploys, deflation begins immediately as the gas escapes through vent(s) in the fabric (or, as it’s sometimes called, the cushion) and cools. Deployment is frequently accompanied by the release of dust-like particles, and gases in the vehicle’s interior (called effluent). Most of this dust consists of cornstarch, French chalk, or talcum powder, which are used to lubricate the airbag during deployment. For most people, the only effect the dust may produce is some minor irritation of the throat and eyes. Generally, minor irritations only occur when the occupant remains in the vehicle for many minutes with the windows closed and no ventilation. However, some people with asthma may develop a potentially lethal asthmatic attack from inhaling the dust.Because of the airbag exit flap design of the steering wheel boss and dashboard panel, these items are not designed to be recoverable if an airbag deploys, meaning that they have to be replaced if the vehicle has not been written off in an accident. Moreover, the dust-like particles and gases can cause irreparable cosmetic damage to the dashboard and upholstery, meaning that minor collisions which result in the deployment of airbags can be costly accidents, even if there are no injuries and there is only minor damage to the vehicle structure.
  • Technical issues with Airbags
    Inadvertent airbag deployment while the vehicle is being serviced can result in severe injury, and an improperly installed or defective airbag unit may not operate or perform as intended. Some countries impose restrictions on the sale, transport, handling, and service of airbags and system components. For example, in Germany, airbags are regulated as harmful explosives; only mechanics with special training are allowed to service airbag systems.
  • Associated costs with service, repair and replacement
    There have been many instances when the automobile manufacturers like Toyota, Honda, Hyundai, Ford, Nissan, BMW were forced to recall sold vehicles only to replace some faulty part in the airbag module. These recalls have been a global activity and while the replacement time itself is just 10-15 minutes, it adds to the pain of the consumer. In a market like India, consumers would at the first instance prefer not to buy a car equipped with airbags in order to avoid any inconvenience caused due to recall of the vehicle for replacement of a faulty part in the airbag module.
  • Limited Expertise and Availability
    The airbag module manufacturing is done by a handful of companies and the demand is extraordinarily high in the global market. This is primarily attributable to the mandate in USA to make airbags mandatory in every car. The technology to manufacture airbags is not cheap and it is not an easy access market. These factors coupled with the lust for making profits has led to serious doubts on the quality and reliability of equipment used by the airbag module manufacturers and led the cost and convenience-centric Indian consumers to refrain from buying the models of cars that include airbags as an optional accessory.

Limitations for the Indian Consumer
Air bags in India are expensive because most of the parts, such as inflators, are imported. In the absence of rules imposing their use in a country of poorly maintained vehicles and overcrowded, badly lit and potholed roads, carmakers often opt not to add a costly component that could drive up automobile prices. Until recently, airbags remained an accessory available only with the top end variant of the car and were unnecessarily coupled with other non-essential accessories such as music systems, climate control air conditioning, sun roofs etc. However, thanks to the efforts of Ministry of Road Transport and Highways, now airbags are a part of an optional package wherein the airbag is available as an optional accessory right for the very first or base model of a car although they still remain optional and it has been left on the cost conscious Indian consumers to decide if they would want to shell out extra money for their own safety.

It cannot be said that airbag is the perfect technology and adapting to it would solve the mass number of road accident casualties in India but definitely it would be a step forward. We do have moved in a forward directing over the past few years, the presence of the option to get an airbag fitted car is now available right from the very basic model however the consumer is still burdened with a visible price hike which as per the consumers is just for one feature. The Consumer cannot be expected to understand all the implications and it is best if airbags are made mandatory in all variants with no option for the consumer to choose and the enforcement of this decision would be fairly possible as the Government would have to regulate and frame rules which would be followed by just one section and that would be the automobile manufacturers. There have been instances where the Government has easily been able to enforce its decision on the automobile manufacturers (an example of this being always on headlamp for two wheelers, BS 4 emission standards etc). Being an easily available technology, the manufacturing of airbags can be promoted by the Government by incentivizing the production in order to meet the requirements of the local market, this move would promote employment and also help saving precious lives.