August 2003 | Philip Chacko

Safety first

Indica's safety characteristics are testimony to the commitment of Tata Motors in providing the best protection to the user

A computer-generated simulation of an Indica crashing
Nikhil Hariharan has vague memories of the day he could have died, but that decisive moment when he sidestepped disaster is etched in his mind. Mr Hariharan was driving to work on a bright March morning when an oncoming car swung out of control and slammed head-on into his vehicle. "The crash happened in a split second, but I remember it in slow motion." he says. "The car seemed to implode. The bonnet, the dashboard, the steering wheel, everything kind of caved in."

Mr Hariharan escaped with minor bruises, but the driver whose recklessness led to the crash wasn’t so fortunate: he ended up with serious injuries and many excruciating months in a hospital. Looking at the two crashed vehicles in the immediate aftermath of the accident, one would have presumed the opposite effect on those inside them. The front portion of Mr Hariharan’s car, an Indica, was a wreck, while the other vehicle emerged from the collision relatively undamaged.

The sharply contrasting results of the crash on the two cars and their drivers were reflective of the different safety principles that came into play at the moment of impact. Mr Hariharan’s Indica was engineered to protect him in such a situation; his fellow-protagonist in the bust-up had no such shield. "I did not give the safety factor much thought when I purchased the Indica," says Mr Hariharan, "but the crash convinced me that this is the safest car of its kind in India. It saved my life."

The Indica’s safety characteristics are testimony to the commitment of Tata Motors, the manufacturer of the car, in providing the best possible protection to those using its vehicles. The entity entrusted with the task of ensuring passenger safety is the company’s crash-test facility. Located at Tata Motors’ huge plant in Pune, this is the only installation of its kind in the country.

Established in 1996, the facility currently has a staff strength of 21, among them 11 engineers. That’s a small part of the Tata Motors' workforce, but the job done here has been vital to the success of the Indica and other products in the company’s passenger car stable. "Right from the beginning, crash testing was identified as one of the critical areas in building a world-class car," says Anil Kumar, project manager (vehicle safety systems) at Tata Motors.

As with most components of the car project, Tata Motors took the indigenous road on crash testing, preferring to develop capabilities in-house rather than import them. "There were no crash-testing benchmarks in India when we started out; we had to learn everything from scratch," says Mr Kumar. "We wanted to integrate the facility and modify it as we grew. That’s what we have done."

There are two complementary aspects of crash testing: simulation, through powerful computers and sophisticated software, and the physical crashing of vehicles, at the prototyping stage and, later, off the production line. The philosophy guiding this endeavour is that in the event of an accident protecting the passenger becomes paramount. "The idea is to use every part of the vehicle in some way to save the occupant rather than the vehicle."

The aim is to make sure that the risk of serious injuries and intrusions are controlled. Then come secondary safety factors such as doors staying closed during a crash (to prevent passengers from being thrown), making evacuation easy (doors should not get jammed up), ensuring seats don’t get so distorted that removing the passenger from the vehicle becomes difficult, and eliminating the risk of a fire breaking out. "We optimise the vehicle’s structure to make it endure the damage caused by a crash. That way we can protect the car’s occupants."

A crucial component in the safety process is crumple zones. These are vacant spaces in the front portion of the car which act as cushions, where metal parts are supposed to deform and absorb all the kinetic energy of the vehicle. These deformations cannot be allowed to happen in an uncontrolled fashion; they have to happen in the designated areas, which then ensure that the passenger compartment is rigid and stable.

In the case of a side collision, the space between the car’s body and the occupant is much less than with the front and rear. Intrusions here have to be much lower for the same impact. There are metal barriers, or side-intrusion beams, that do the safety job here. Add to this the materials used inside the car. These plastic parts are designed to deform and soften the impact to occupants rather than crack up and expose sharp edges.

Finding out whether these different attributes will perform efficiently in an accident is the crash-testing facility’s responsibility. The actual crashing of a car is spectacular, but it is computer-aided simulation that constitutes the greater, more comprehensive safety effort.

Simulating every accident type is impossible, which is why a number of standardised crash tests — based on international classifications and industry practices — are used in the development of the vehicle. This defines a repeatable way of conducting crashes, so that improvements can be quantified and modifications made.

In the simulation phase extensive use is made of what’s known as ‘finite element analysis’, where the vehicle is broken down into tiny parts so that the impact of a crash on any given area can be precisely calculated (the Indica model comprises around 2 lakh elements). By the time the car is ready to undergo a physical crash test, engineers have a pretty good idea of what’s going to happen. The actual crashing works, in a way, to validate the findings of the simulated collision.

For every physical crash test there are about 30 simulated ones. "We consciously take decisions to simplify the simulation model in order to reduce the computational time. It takes 12 hours to complete one simulation, and this happens on a multiprocessing machine. A less powerful machine will probably take a week to run such a simulation."

The final product authentication happens with the physical crash test. This is a dramatic affair. The car is backed away from a 116-tonne barrier made of steel and concrete. An electric motor, mounted behind the barrier and controlled digitally, yanks the car down the runway using a steel wire rope. The car hits the barrier at 56kmph, right after the rope has released it to run free. It takes about 0.2 seconds from the time the car hits the barrier until it stops.

This is when seven high-speed cameras, shooting at around 1,000 frames per second, capture the moment for future analysis. These cameras, sometimes placed inside the car, can generate about 200 images each of the crash.

Inside the vehicle there are two crash test dummies wired with about 50 sensors each to capture the impact of the collision on different parts of the human body. Given that these dummies cost upwards of Rs90 lakh each, it’s a good thing that they can be used again. The sensors in the dummies measure, among other things, acceleration in various locations (to determine the probability of injury), the amount of force exerted on different body parts during a crash, and how much the chest deflects during a crash.

Besides the sensors embedded in the dummies, there are more than 30 other sensors spread out inside the car. The data thus captured is fed into a computer to understand the exact impact of the crash on the car and its dummy occupants. Based on what emerges, the car’s safety features are tweaked and improved.

The Indica and its siblings have gone through numerous crash tests, simulated and actual, to make driving safer for those using them. Tata Motors has expended considerable effort and resources on this exercise. Nikhil Hariharan and many others are proof that this labour has been worth it.