Automobile safety is the study and practice of design, construction, equipment and regulation to minimize the occurrence and consequences of automobile accidents. Road traffic safety more broadly includes roadway design. One of the first formal academic studies into improving vehicle safety was by Cornell Aeronautical Laboratory of Buffalo, New York. The main conclusion of their extensive report is the crucial importance of seat belts and padded dashboards. However, the primary vector of traffic-related deaths and injuries is the disproportionate mass and velocity of an automobile compared to that of the predominant victim, the pedestrian.
In the United States a pedestrian is injured by an automobile every 8 minutes, and are 1.5 times more likely than a vehicle's occupants to be killed in an automobile crash per outing. Improvements in roadway and automobile designs have steadily reduced injury and death rates in all first world countries. Nevertheless, auto collisions are the leading cause of injury-related deaths, an estimated total of 1.2 million in 2004, or 25% of the total from all causes. Of those killed by autos, nearly two-thirds are pedestrians. Risk compensationtheory has been used in arguments against safety devices, regulations and modifications of vehicles despite.
In order to understand how seat belts and air bags provide protection it is important to know about occupant movement in the event of an accident. Upon impact the vehicle either decelerated rapidly or accelerated when hit by a moving object such as another vehicle. When this occur inertia always causes the occupants to move in the opposite direction to the applied impact force. The safety systems are intended to reduce the risk of contact between the occupants and vehicle interior. However glasses generally prevent the risk of injuries caused by objects entering the vehicle from outside.
ETD AND SEAT BELT FORCE LIMITER:
The front seat belts and some of the outer rear belts are equipped with ETD’s. In addition in some seat belt systems, belt force limiters are included. If deployed in event of an accident, an ETD reduces these at belt slack. The occupant is restrained earlier and thus participates sooner in the vehicle’s deceleration decreasing the occupant load during the collision. In addition seat belt is also equipped with a force limiter it reduces upon activation the peak seat belt force excreted on the occupant. The belt force limiter is tuned to the front air bag which in turn takes on some of the seat belt induced forces thus providing a more even load distribution. When the ignition is on the ETD s are deployed during a frontal or rear end collision of sufficient severity that is accidents with high longitudinal deceleration or acceleration sensed and made more safer.
ACTIVE AND PASSIVE SAFETY
The terms "active" and "passive" are simple but important terms in the world of automotive safety. "Active safety" is used to refer to technology assisting in the prevention of a crash and "passive safety" to components of the vehicle (primarily airbags, seatbelts and the physical structure of the vehicle) that help to protect occupants during a crash.
Crash avoidance systems and devices help the driver — and, increasingly, help the vehicle itself — to avoid a collision. This category includes:
The vehicle's headlamps, reflectors, and other lights and signals The vehicle's mirrors
The vehicle's brakes, steering, and suspension systems
A subset of crash avoidance is driver assistance systems, which help the driver to detect obstacles and to control the vehicle. Driver assistance systems include:
DADS:' DADS : Driver Alertness Detection System System to prevent accident caused by fatigue.
Automatic Braking systems to prevent or reduce the severity of collision.
Infrared night vision systems to increase seeing distance beyond headlamp range.
Adaptive headlamps control the direction and range of the headlight beams to light the driver's way through curves and maximize seeing distance without partially blinding other drivers.
Reverse backup sensors, which alert drivers to difficult-to-see objects in their path when reversing.
Lights and reflectors:
Vehicles are equipped with a variety of lights and reflectors to mark their presence, position, width, length, and direction of travel as well as to convey the driver's intent and actions to other drivers. These include the vehicle's headlamps, front and rear position lamps, side marker lights and reflectors, turn signals, stop (brake) lamps, and reversing lamps. School buses and Semi-trailer trucks in North America are required to bear retro reflective strips outlining their side and rear perimeters for greater conspicuity at night.
Daytime running lamps have been required in Nordic countries since the mid-1970s, in Canada since 1990, and throughout the European Union since 7 February 2011.
Unused safety features:
Many different inventions and ideas which may or may not have been practical about auto safety have been put forward but never made it to a production car. Such items include the driver seat in the middle (to give the person a better view) (the exception being the Mclaren F1 sports car), rear facing seats (except for infant car seats), and control stick steering.
Post-crash survivability is the chance that drivers and passengers survive a crash after it occurs. Technology such as Advanced Automatic Collision Notification can automatically place calls to emergency services and send information about a vehicle collision.
Infants and children:
Children present significant challenges in engineering and producing safe vehicles, because most children are significantly smaller and lighter than most adults. Safety devices and systems designed and optimized to protect adults — particularly calibration-sensitive devices like airbags and active seat belts — can be ineffective or hazardous to children. In recognition of this, many medical professionals and jurisdictions recommend or require that children under a particular age, height, and/or weight ride in a child seatand/or in the back seat, as applicable. In Sweden, for instance, a child or an adult shorter than 140 cm is legally forbidden to ride in a place with an active airbag in front of it. Childand driver-controlled power window lockout controls prevent children from opening doors and windows from inside the vehicle.
Infants left in cars:
Very young children can perish from heat or cold if left unattended in a parked car, whether deliberately or through absentmindedness. In 2004 the U.S. NHTSA estimated 25 fatalities per year among children left in hot cars.
When pregnant, women should continue to use seatbelts and airbags properly. A University of Michigan study found that "unrestrained or improperly restrained pregnant women are 5.7 times more likely to have an adverse fetal outcome than properly restrained pregnant women". If seatbelts are not long enough, extensions are available from the car manufacturer or an aftermarket supplier then.