Here’s all you need to know about automotive safety features

While the shell of a car is the first line of defence in absorbing the impact, the airbags act as a supplementary restraint system, cushioning the blow and acting as barriers between the occupant and the car’s own shell, steering, dashboard or the projectile hitting it. The term “supplementary” is the operative one here, implying that airbags are designed to assist seat-belts in protecting you, not the other way around.

At an entry level, across most countries, most cars get a driver and front passenger airbag as standard fitments. The airbag is essentially a nylon bag, folded, compressed and placed inside different cavities in a car, depending on the number of airbags available inside a car. The number ranges from two to upwards of 10, in top-end luxury cars (including knee, side, curtain and belt airbags, among others). Upon impact, accelerometers all over the car detect sudden deceleration and send a signal to a small electronic device which ignites and, within milliseconds, releases nitrogen which fills up the airbag. The airbag then absorbs the impact post which it deflates immediately, with the car now stationary. Airbags are only designed to work once. They are also designed to inflate at speeds between 100-150 kph.

Therefore, it is imperative that you’re held in place by your seatbelt.

Driver airbags were made mandatory in India only recently (2019) while a rule mandating the placement of a front passenger airbag was put into effect at the beginning of 2022. At present, legislation is being put in place that will make six airbags mandatory for all cars.

SRS Airbag module

This is a small electronic device that controls the airbag’s deployment and stores crash data. In the event of a crash, the SRS electronic module needs to be reset to ensure that the car, once repaired, can deploy airbags again.

ABS

The anti-lock braking system or ABS ensures that upon hard braking, wheels don’t lock up dragging the car well beyond the desired braking point (also called “skidding”). How ABS works is by essentially pumping the brakes — except it happens hundreds of times per second and is controlled electronically via the brains of the car, that is, the Electronic Control Unit (ECU).

The ECU collects data from speed sensors which calculate the speed at which the wheels are rotating. Valves in the brake line then release pressure repeatedly in order to ensure that the wheels don’t lock up. This helps keep the car stable during hard braking, especially on slippery surfaces and inadvertently ensures shorter braking distance. ABS also allows the car to turn faster, while under heavy braking, in order to avoid collision. ABS sensors are usually located within each wheel’s rotor.

HUD

Yet another active safety measure, the Heads-up-display feature uses simple mirror work to reflect the accurate speed and other critical data to fall within the line of sight of the driver and the road ahead. This ensures that the driver does not take the eyes off the road, which, in turn, goes a long way in ensuring that the car doesn’t veer off course.

Traction Control

Using the same sensors as ABS, traction control works to prevent wheel-spin by modulating power levels. When ABS detects a wheel’s revolutionary speed to be much higher than the other wheels it modulates engine power, giving it ample time to slow down. ESC works in tandem with traction control in most modern vehicles, automatically applying measured braking inputs on the spinning wheel.

When the system is operational, for example, under heavy acceleration or on slippery surfaces, a traction control light flickers on the dashboard or the instrument cluster, suggesting that the system is at work. Although traction control can be turned off — and often is turned off on racetracks to offer uninterrupted power supply from the engine — its intervention over the years has become increasingly undetectable from behind the wheel.

Crumple Zone

Crumple zones are the areas in a car’s shell that are designed to crumple and absorb the kinetic impact of a collision. Located at the front and rear extremities of a car, crumple zones are designed to offer just the right amount of resistance to kinetic impact, in order to ensure that the passenger compartment remains unaffected.

Located primarily at the front and rear, with some car models offering smaller crumple zones on the side, crumple zones are designed differently for different types of vehicles. But ultimately, their job is to ensure impact absorption and protect the passenger compartment.

Shell integrity

Airbags alone won’t make your car safer in the event of a crash. Sound structural integrity ensures that the impact of the crash is evenly spread in a manner that doesn’t transmit the kinetic force of the crash to the A, B and C-pillars, steering column, pedal and floor panel which can amplify the damage caused to the body in the event of a crash.

It must also ensure that doors remain as unimpacted as possible and can open easily post crash. Car shells have come a long way in offering great protection with several manufacturers using highly tensile aluminium (carbon fibre in case of certain performance and racing cars) monocoques.

ADAS

As automotive AI becomes more sophisticated, with various levels of autonomous driving now operating in different parts of the world, Advanced Driving Assistance or ADAS features are becoming increasingly common across cars. These include driver drowsiness detection, active lane assist, active cruise control, active park assist, automated emergency braking, blind spot monitoring, lane departure warning, etc using a mix of infrared sensors, cameras and occasionally radar technology (wherever it’s legal to operate it) to keep the car constantly vigilant.

Some higher levels of autonomous driving, available in cars like the Tesla Model S also offer technology that allows the car to steer in and out of parkways and traffic without any manual intervention. That said, all cars featuring autonomous driving systems insist that a driver always be behind the wheel, ready to intervene when need be.

ESC - Electronic Stability Control

Using individual sensors on each wheel, ESC monitors steering wheel inputs and overall speed, constantly working in the background to ensure that it can intervene and keep the car pointing in the right direction. Introduced in the mid-90s, ESC works like a class monitor, using other electronic aids like ABS and traction control to keep the car from veering off course.

Using a yaw sensor located as close to the centre of the vehicle as possible, ESC deploys ABS to slow a car down, controlling the level of oversteer, and often understeer, from taking the car off course. Between ESC, responsible for monitoring side-to-side motion, and traction control, responsible for monitoring front-to-back motion, the car remains pointing in the right direction.

EBD - Electronic Brake Distribution

Telematics have proven that not all wheels on a car need to apply the same amount of braking input in order to effectively bring a car to a halt. That’s where EBD comes in. Based on the vehicle’s turning speed, angle, etc, some wheels carry a heavier load, necessitating differing amounts of pressure to be applied to different wheels.

Using speed sensors and valves on the brakes, the car’s ECU modulates the amount of brake force applied on each wheel. By regulating the amount of brake fluid pumped into the brake lines, EBD works alongside other tech like ESC and ABS to ensure that the car remains under the driver’s control.

ISOFIX mounts

These are attachment points for the child safety seat to be attached to a car’s seat, as a seat designed for a grown up human may not offer the same protection as a child’s seat. ISOFIX mounts help ascertain the child safety rating in a car. It should be noted that a passenger airbag facing the child safety seat should be disabled as an airbag travelling at speeds upwards of 150 kph can cause injury to a child. Check with your car manufacturer on how to disable the airbag, and re-engage it once the seat has been removed.

Tire Pressure Monitoring System (TPMS)

Usually located in the space between the tyre and the wheel rim, tire pressure monitoring systems are designed to tell you whether one or more tires on your car are underinflated. This reduces the chance of a blowout during high speeds. The correct tyre pressure can make a huge difference to ride quality and also improve mileage on a car.

Rollover Stability System

An advanced form of electronic stability control, rollover systems first warn the driver and occupants of the possibility of a rollover before initiating corrective action to avoid a rollover. If the vehicle’s centre of gravity isn’t low, and a rollover occurs, the system then works on deploying curtain airbags which will stay inflated longer than front airbags are designed to. Electric vehicles (EVs), which have a much lower centre of gravity, are less prone to rollover, but can topple in case of a high-speed collision with a divider or boulder.