Crashworthiness is the ability of a structure to protect its occupants during an impact. This is commonly tested when investigating the safety of vehicles.
Automobile manufactures have a responsibility to design and build vehicles that are not unreasonably dangerous. Automobiles must be able to sustain normal forces exerted in an accident. Depending on the nature of the impact and the vehicle involved, different criteria are used to determine the crashworthiness of the structure. Crashworthiness may be assessed either prospectively, using computer models or experiments, or retrospectively by analyzing crash outcomes. Several criteria are used to assess crashworthiness prospectively, including the deformation patterns of the vehicle structure, the acceleration experienced by the vehicle during an impact, and the probability of injury predicted by human body models. Injury probability is defined using criteria, which are mechanical parameters (e.g., force, acceleration, or deformation) that correlate with injury risk.
Examples of defective automobile crashworthiness cases include:
- SUV Rollover
- 15- Passenger Van Rollover
- Tire Failure
- Roof Crush
- Defective Seat Belts
- Child Safety Seats
- Door Latches
- Seat Back Collapse
- Airbag Failure
- Sudden Acceleration
- Brake Shift
- Shifts into Drive from Park
- Oil Sludge
- Faulty Ignition
- Fuel Fed Fire
- Seat Belt Failure
To find out more about the safety of the vehicles you are driving and for more information about vehicle safety research go to the National Highway Traffic Safety Administration website.
Airbags use a complex system that involves a microchip-embedded accelerometer and a sensor to “tell” the airbag to inflate when there’s an impact equal to hitting a brick wall at about 1015 miles per hour.
Airbags are deployed at up to 200 miles per hour, and if they deploy at the wrong place, or at the wrong time, they can cause a serious injury or a fatality.
Airbags can injure or kill vehicle occupants. To provide crash protection for occupants not wearing seat belts, U.S. airbag designs trigger much more forcefully than airbags designed to the international ECE standards used in most other countries. Recent airbag controllers can recognize if a belt is used, and alter the bag deployment parameters accordingly.
Injuries such as abrasion of the skin, hearing damage from the extremely loud 165-175 db deployment explosion, head injuries, eye damage, and broken nose, fingers, hands or arms can occur as the airbag deploys. Most vehicle airbags are inflated using hot gas generated by a chemical process. Using hot gas allows the required pressure to be obtained with a smaller mass of gas than would be the case using lower temperatures. However, the hot gas can pose a risk of thermal burns if it comes in contact with the skin during deployment and occupant interaction. Burns are most common to the arms, face and chest. These burns are often deep dermal or second-degree burns that take longer to heal and risk scarring.
In 1990, the first automotive fatality attributed to an airbag was reported, with deaths peaking in 1997 at 53 in the United States. TRW produced the first gas-inflated airbag in 1994, with sensors and low-inflation-force bags becoming common soon afterwards. Dual-depth (also known as dual-stage) airbags appeared on passenger cars in 1998. By 2005, deaths related to airbags had declined, with no adult deaths and two child deaths attributed to airbags that year. Injuries remain fairly common in accidents with an airbag deployment.
Serious injuries are less common, but severe or fatal injuries can occur to vehicle occupants very near an airbag or in direct contact when it deploys. Such injuries may be sustained by unconscious drivers slumped over the steering wheel, unrestrained or improperly restrained occupants who slide forward in the seat during pre-crash braking, and properly belted drivers sitting very close to the steering wheel.
Improvements in sensing and gas generator technology have allowed the development of third generation airbag systems that can adjust their deployment parameters to size, weight, position and restraint status of the occupant. These improvements have demonstrated a reduced injury risk factor for small adults and children who had an increased risk of injury with first generation airbag systems.
Air bag fatality statistics
From 1990 to 2008, the U.S. National Highway Traffic Safety Administration identified 175 fatalities as because of air bags. Most of these (104) have been children, while the rest are adults. About 3.3 million air bag deployments have occurred and the agency estimates more than 6,377 lives saved and countless injuries prevented.
A rear-facing infant restraint put in the front seat of a vehicle places an infant’s head close to the airbag, which can cause severe head injuries, or death if the airbag deploys. Some modern cars include a switch to disable the front passenger airbag (although not in Australia, where rear-facing child seats are prohibited in the front where an airbag is fitted), in case a child-supporting seat is used there.
In vehicles with side airbags, it is dangerous for occupants to lean against the windows, doors, and pillars, or to place objects between themselves and the side of the vehicle. Articles hung from a vehicle’s clothes hanger hooks can be hazardous if the vehicle’s side curtain airbags deploy.
A Variety of Defects
The problems with airbags both front-deployed airbags and the new side-deployed airbags have been numerous, including:
- Failure to deploy
- Late deployment
- Traumatic deployment
- Incomplete deployment
- Inadvertent deployment (airbag deploys at the wrong, unnecessary time)