Car safety
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Car safety
Driving under the influence | Driver's license | Radar detector | Road safety
Car safety is the avoidance of
car accidents or the minimization of harmful effects of accidents,
in particular as pertaining to human life and health. Special safety
features have been built into cars for years, some for the safety of
car's occupants only, some for the safety of others.
Distance crossed by vehicles in a city (here,
Paris) during 1
second (typical time to react to an emergency).
Road traffic injuries represent about 25% of worldwide injury-related deaths
(the leading cause) with an estimated 1.26 million deaths in 2000 (Peden 2002).
Major factors in accidents include
driving under the influence of alcohol or other
drugs; inattentive driving; driving while fatigued or unconscious;
encounters with road hazards such as snow, potholes, and crossing animals; or
reckless driving.
History
Car safety became an issue almost immediately after the invention of the
automobile, when
Nicolas-Joseph Cugnot crashed his steam-powered "Fardier" against a wall in
1771. The first recorded automobile fatality was Bridget Driscoll on August 17,
1896 in London.
In 1958, the United Nations established the World Forum for Harmonization of
Vehicle Regulations, an international standards body advancing auto safety. Many
of the most life saving safety innovations, like seat belts and roll cage
construction were brought to market under its auspices.
In 1966, the US established the
United States Department of Transportation (DOT) with automobile safety one of
its purposes. The National Transportation Safety Board (NTSB) was created as an
independent organization on April 1, 1967, but was reliant on the DOT for
administration and funding. However, in 1975 the organization was made
completely independent by the Independent Safety Board Act.
The NTSB and its European equivalent, EuroNCAP have each issued independent
safety tests for all new automobiles, without reciprocity.
In June, 2004
the NTSB released new tests designed to test the rollover risk of new cars and
SUVs. Only the
Mazda RX-8 got a 5-star rating. However, the correlation between official crash
test results and road deaths in vehicles is not exact. An alternative method of
assessing vehicle safety is to study the road accident statistics on a
model-by-model basis.
Despite technological advances, the death toll of car accidents remains high:
about 40,000 people die every year in the US. While this number increases
annually in line with rising population and increased travel, the rate per
capita and per vehicle miles travelled decreases. In 1996 the US has about 2
deaths per 10,000 motor vehicles, comparable to 1.9 in Germany, 2.6 in France,
and 1.5 in the UK
[1]. In 1998 there were 3,421 fatal accidents in the UK, the fewest since
1926
[2].
A much higher number of accidents result in permanent disability.
Color
A Swedish study found pink cars safest, with black cars most likely to be
involved in crashes, and also showed
Saab to be the
"safest car in Sweden [In terms of passive safety]" (Land transport NZ 2005).
An Auckland, New Zealand study found a significantly lower risk of serious
injury in silver cars; with high risks for brown, black, and green cars.
(Furness et al, 2003).
Pregnant women
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"
[3]. If seatbelts are not long enough, extensions are available from the car
manufacturer or an aftermarket supplier.
Children
Car safety is especially critical for young children, as car safety is
generally designed for normal sized adults. Safety features that could save an
adult can actually cause more damage to a child than if the feature was not
there. It is important to review with others, who may be supervising the child,
the rules for car safety. All children age 12 and under should ride in the back
seat. This is especially the case if there are airbags in the front seat, as
airbags are only designed to protect adults and may injure children.
Child safety locks prevent children from accidentally opening doors from
inside the vehicle, even if the door is unlocked. The door, once unlocked, can
then be opened only from the outside.
Infants
Newborn babies should be put in a
car seat until they weigh at least 20 or 22 pounds (10 or 11 kg). These
carriers are designed to be placed in the rear seat and face towards the rear
with the baby looking towards the back window. Some of these carriers are
"Convertibles" which can also be used forward facing for older children. With
infants, these should only be used facing the rear. Harness straps
should be at or below shoulder level.
A rear-facing infant restraint must never be put in the front seat of a
vehicle with a front passenger air bag. A rear-facing infant restraint places an
infant's head close to the air bag module, which can cause severe head injuries
or death if the air bag deploys. Modern cars include a switch to turn off the
airbag system of the passenger seat, in which case a child-supporting seat must
be installed.
Toddlers
Toddlers over 1 year old and between 20 and 40 pounds (10 and 20 kg) should
be placed in forward facing child seats or convertibles placed in the rear seat.
Harness straps should be at or above the child's shoulders.
Young children
Children who weigh less than 80 pounds (40 kg), are younger than 8, or are
shorter than 4 ft 9 in (1.4 m) are advised to use belt positioning
booster seats which raise them to a level that allows seat belts to work
effectively. These seats are forward facing and must be used with both lap and
shoulder belts.
Make sure the lap belt fits low and tight across the lap/upper thigh area and
the shoulder belt fits snug crossing the chest and shoulder to avoid abdominal
injuries.
There are two main types of booster seats. If the car's back seat is lower
than the child's ears, a high back booster seat should be used to help
protect the child's head and neck. If the car's seat back is higher than the
child's ears, a backless booster seat can be used.
Teenage Drivers
Most areas in the United States allow teens the privilege to drive at the age
of 16. This age ranges in other countries but all teen drivers are relatively
inexperienced compared to other drivers. This lack of experience leads to an
increased risk of accidents among this demographic. Several resources are
available to help teen drivers including
TeenDriving.comand AutoExtra.com's kids first car tips and recommendations.
Safety features
Avoidance
To make driving safer and prevent accidents from occurring, cars may have the
following active safety features:
Turn signals and brake lights, including Center High Mounted Stop Lamps (CHMSL)
Anti-lock braking system (ABS) (also Emergency Braking Assistance (EBA),
often coupled with Electronic brakeforce distribution (EBD), which prevents
the brakes from locking and losing traction while braking. This shortens
stopping distances in almost all cases.
Inboard brakes allow large fade resistant discs or drums, without
contributing to unsprung weight and wheel bounce, which degrade braking,
handling and ride, and increase mechanical loads.
Traction control (TCS) actuates brakes or reduces throttle to restore
traction if driven wheels begin to spin.
Four wheel drive (AWD) with a center differential. Distributing power to all
four wheels lessens the chances of wheel spin. It also suffers less from
oversteer and understeer.
Electronic Stability Control (ESC)(also known for Mercedes-Benz proprietary
Electronic Stability Program (ESP), Acceleration Slip Regulation (ASR) and
Electronic differential lock (EDL)). Uses various sensors to intervene when
the car senses a possible loss of control. The car's control unit can reduce
power from the engine and even apply the brakes to prevent the car from
understeering or oversteering.
Dynamic steering response (DSR) corrects the rate of power steering system
to adapt it to vehicle's speed and road conditions.
Lane Departure Warning System (LDWS).
Directional headlights.
Low center of gravity and other conventional features promoting good car
handling and braking, and helping to avoid rollover.
Large (relative to weight) high performance tires, suited to the weather and
road conditions, contribute to braking and handling. Soft high histeresis
rubber, tread and cord design are important.
Visibility for the driver, mirrors, elimination of blind spots and possibly
other awareness aids such as radar, wireless vehicle safety communications
and night vision.
Death Brake; there is a move to introduce deadman's braking into automotive
application, primarily heavy vehicles, there may also be a need to add
penalty switches to cruise controls.
Four wheel steering gives, at the cost of mechanical complexity, quicker,
more accurate manoeuvres at high speed and/or decreased turning circle at
low speed. It may also help stability.
Damage control
Front drivers-side airbag
When an accident is imminent, various passive safety systems work together to
minimize damage to those involved. Much research has been done using
crash test dummies to make modern cars safer than ever. Recently, attention has
also been given to cars' design regarding the safety of pedestrians in
car-pedestrian collisions. Controversial proposals in Europe would require cars
sold there to have a minimum/maximum hood height. This has caused automakers to
complain that the requirements will restrict their design choices, resulting in
ugly cars. Others have pointed out that a notable percentage of pedestrians in
these accidents are drunk. From 2006 the use of
"bull bars"
(known as "roo bars" in Australia), in fashion on
4x4s and SUVs,
will be illegal.
- Seatbelts (or safety belts) keep a person from being thrown forward or
ejected from the vehicle.
- Airbags
- Front airbags inflate in a medium speed head on collisions to
cushion the blow of a head on the dashboard or steering wheel.
- Side airbags inflate in a side (T-bone) collision to cushion the
torso
- Curtain airbags protect the heads of passengers in a side collision
- Bumpers to withstand low-speed collisions without damaging bodywork.
-
Crumple zones absorb the energy of an impact when the car hits something
- Crash box to dissipate impact forces
- Collapsible steering column, sometimes provided with steel sheet
bellows.
-
Crash compatibility can be improved by matching vehicles by weight and
by matching crumple zones with points of structural rigidity, particularly
for side-on collisions. Some pairs of vehicle front end structures interact
better than others in crashes. Widely different height and body on rail
frame design are particularly bad.
- Cage construction is designed to protect vehicle occupants. Some racing
vehicles have a tubular
roll cage
- Reinforced side door structural members
- Fuel pump shutoff devices turn off gas flow in the event of a collision
for the purpose of preventing
gasoline
fires.
- Light weight: the possible damage a vehicle can do to outside people and
things is roughly proportional to its kinetic energy, which is its weight
times the square of its speed.
- Active
pedestrian protection systems
[4].
See also
External links
References
- Furness, Sue, J Connor, E Robinson, R
Norton, S Ameratunga, R Jackson (2003-12-20).
Car colour and risk of car crash injury: population based case control
study.. British Medical Journal 327:1455-1456. BMJ Publishing
Group. URL accessed on 2006-01-01.
- IEEE Communications Magazine, April 2005, "Ad Hoc Peer-to-Peer
Network Architecture for Vehicle Safety Communications"
- IEEE Communications Magazine, April 2005, "The Application-Based
Clustering Concept and Requirements for Intervehicle Networks"
- (2005).
Safe vehicle colours.. Land transport NZ. URL accessed on
2006-01-01.
- Peden M, McGee K, Sharma G. (2002).
The injury chart book: a graphical overview of the global burden of
injuries.. (PDF)
Geneva, World Health Organization. URL accessed on 2006-01-01.
ISBN 924156220X
- Physics Today, January 2006, "Vehicle Design and the Physics of
Traffic Safety"
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