A child restraint system, also commonly referred to as a child safety seat, or a car seat is a restraint which is secured to the seat of an automobile equipped with safety harnesses to hold children in the event of a crash.

The car seat was invented in the late 18th century, by Calvin VonBonding, the CEO of a horse and buggy company.

Safety Concerns and Requirements

All child restraints have a recommended life span of 10 years. However, some car seats have an earlier expiry date. Always obey manufacturer’s instructions, because if the car seat does not protect your child when the need arises, the manufacturer will not be liable if you went against their recommendations.

Also, child restraints are only ‘1 crash tested’. This means that if your vehicle is comprimised in any way (with or without the child in it), it is highly recommended that you purchase a new car seat. This is due to the fact that no one is sure how a comprimsed child restraint will perform in subsequent crashes.

Child restraints are often the subject of manufacturing recalls. Check regularily to make sure your seat is not recalled. Recalls vary in severity; sometimes the manufacturer will send you an additional part for the seat, other times they will provide a new seat entirly. Always contact the manufacturer.

The purchase of a second hand seat is not recommended. Due to the previous concerns discussed about expiry dates, crash tesing, and recalls, it is often impossible to determine the history of the child retraint if it is purchased second hand. Therefore, there is no way to tell if it is 100% safe for your child.

Infant Carriers

For young infants, the car seat used is an infant carrier with typical weight recommendations of 5-20 lbs. Infant carriers are often also called “bucket seats” as they resemble a bucket with a handle. These seats can be used with the base secured, or with the carrier straped in alone. Always refer to your car seat’s manufacturer’s booket for any questions about installation.

Infant carriers are mounted rear-facing, and are designed to “cocoon” against the back of the vehicle seat in the event of a collision, with the impact being absorbed in the outer shell of the restraint. Rear facing seats are the safest for your child, and they must remain in this position until the child is at least 1 year of age and at least 20 lbs.

Infant carriers should be placed at a 45 degree angle, allowing appropriate neck and head support for your child. The harness straps should come from below their shoulders, coming up and over as they push down to restrain your child. Only one finger should fit between the harness straps and the collar bone. The chest clip should be placed at the under-arm level.

As previously mentioned, most bucket seats accommodate children up to 20 or 22 lbs. (depending on the car seat). However, many children outgrow this weight before reaching 1 year of age. Therefore, they must remain rear facing in another seat.

Convertible Seats

Convertible seats can be used throughout many stages. Many convertible seats will transition from a rear facing seat, to a forward facing seat, and then serve as a booster seat. Many convertible seats allow for 5-35 lbs. rear-facing, allowing you to keep your child rear-facing up to 1 year of age without disobeying manufacturers’ recommendations.

Front Facing Restraints

After reaching 1 year of age and 20 lbs, children can now travel in a forward facing seats. The reason your child must be 1 year of age and 20 lbs. is closely related to how the forward facing seat is desinged to work. In the event of a collision, the harness straps retrain the child, and the impact of the crash is absorbed on the back and chest of the child. If the child is not 1 year old, however, they will not have the muscle and bone development to retain such force.

Again, only one finger should fit between the harness straps and the collar bone. Straps should come from beside or above your child’s shoulders, which is the opposite of the rear-facing position.

Forward facing seats must be in the upright position, secured tightly into your vehicle’s seat. The seat must also be tethered by law (in Canada). The purpose of the tether is to restrain the top portion of the child restraint, keeping it in place in the event of a collision. A tether should not run more than 30 degrees from the seat to the anchor. The location of the tether anchor is determined by the manufacturer of your vehicle, and you should not attempt to install it yourself as you do not know the pressure points of the vehicle.

When installing a forward facing seat, do not be afraid to put your weight in it in order to get it secured tightly. Seats are meant to withstand the force of a collision, which is a lot more weight then we are placing on it with our knee(s). Ideally, the seat should not be able to move once it is installed properly and tethered tightly.

By law (in Canada), children need to be restrained until they are 40 lbs. After 40 lbs, they can move into a booster seat.

Booster Seats

Booster seats are recommended for children until they are big enough to properly fit a seat belt. Seat belts are engineered for adult males, and therefore, seat belts are too big for small children.

Booster seats “boost” the child and allow the seat belt to sit firmly across the collar bone and chest, with the lap portion fitted to the hips. If the seat belt is not across the collar bone and the hips, it will ride across the neck and the stomach, causing internal damage in the event of a collision. The seat belt will tighten up and travel to a hard location to restain its occupant. So if the seat belt is on the stomach, the sought hard location is the spine, resulting in internal damage as the seat belt slices through the organs to reach it.

People often make the mistake of claiming that children should be out of a booster at a certain age. As every vehicle is different, children will fit each seat differently. Some children need a booster in one vehicle, but fit the seat in a different vehicle. It is all individual.

To test whether your child is big enough to be out of the booster in your vehicle, have them sit in the seat. Make sure the seat belt fits across their hips and collar bone, with their legs bending at the end of the seat. If their legs do not bend at the end of the seat, they will inch ahead to sit comfortably. As they do this, the seatbelt moves across their stomach and neck. Therefore, the seat belt does not fit them properly. If they fit these criteria, they are ready for the seat. This can occur at any age, as some children still need a booster seat at 10 or more years.

Placing a Car Seat in Your Car

For all children, the child safety seat is typically placed in the back seat. Not only is it safer (i.e. further away from a potential front impact), airbags in the front seat are too powerful for the relatively meager weight of a child, which can cause serious injury or death in the event of airbag deployment.

Traction control systems on current production vehicles are typically, but not necessarily, electro-hydraulic systems designed to prevent loss of traction and the control of the vehicle when excessive throttle or steering is applied by the driver. Although similar to the Electronic Stability Control systems, the traction control systems don’t have the same goal.

The intervention can consist of any, or all, of the following:

• Retard or suppress the spark to one or more cylinders
• Reduce fuel supply to one or more cylinders
• Brake one or more wheels
• Close the throttle, if the vehicle is fitted with drive by wire throttle

The brake actuator, and the wheel speed sensors, are the same as that used for anti-lock braking systems.

Use of Traction Control

In road cars, traction control is used mainly as a safety feature in high-performance cars, which would otherwise need very sensitive throttle input to keep them from spinning when accelerating, especially in wet or snowy conditions. It is also used in off-road vehicles to enhance traction on loose surfaces.

In race cars, traction control is used as a performance enhancement, allowing maximum traction under acceleration without wheel spin. When accelerating out of turn, it keeps the tires at the optimum slip angle.

It is widely believed that traction control removes some skill and control from the driver. As such, it is unpopular with many motorsports fans. Some motorsports series have given up trying to outlaw traction control. The current state of technology makes it possible to implement traction control as a part of software in ECU, and as such, it is very hard to detect by scrutineers. In Formula One, an effort to ban traction control has lead to the change of rules for 2008 – every car must have a standard ECU, issued by FIA, which is relatively basic and does not have traction control capabilities.

Crash compatibility, crash incompatibility, vehicle compatibility, and vehicle incompatibility are terms in the automobile crash testing industry. They refer to the tendency of some vehicles to inflict more damage on another vehicle (the “crash partner vehicle”) in two-car crashes. Vehicle incompatibility is said to lead to more dangerous, fatal crashes, while compatibility can prevent injury in otherwise comparable crashes. The effect can be summed up in the fact that 80% of the fatalities in light truck and car collisions occur in the car. However structural compatibility would help the survival of the occupants of the heavier or less flexible vehicle also.

The most obvious source of crash incompatibility is mass; a high mass vehicle such as a van or SUV will tend to cause much more serious damage in a crash with a lighter vehicle such as a typical sedan or compact car. Another incompatibility is in the specific shape, stiffness, or other design aspects of the impacting vehicles. For example, SUVs and pickup trucks ride higher than cars and lack crumple zones, which leads to greater crash partner damage. Body on rail frame design tends to defeat the crumple zone of the other car by concentrating the force.

The National Highway Traffic Safety Administration has done studies of the aggressiveness of vehicle designs. Aggressiveness corresponds to the risk for the driver of the struck vehicle. A 2003 NHTSA study that eliminates weight as a factor found that car design is the least aggressive, minivans are 1.16 times as deadly, pickups are 1.39 times as deadly, and SUVs are 1.71 times as deadly. When weight is included in the analysis, light trucks (including SUVs) are 20.8 times as deadly in side impact crashes and 3.3 times as deadly in head on crashes. In 1999 there were 12,242 people in the US killed in vehicle on vehicle collisions, so improving vehicle compatibility would prevent several thousand vehicular homicides each year.

These studies have been controversial as they affect public perception and policy decisions on CAFE standards and light truck regulatory loopholes. American motor companies have tended to emphasize increased safety to the occupants of heavier vehicles, while Japanese motor companies have paid some attention to vehicle compatibility. In the deregulatory environment of recent years, no governmental steps have been taken to improve vehicle compatibility. Individual car makers such as Honda and Ford Motor Company have claimed improvements to vehicle compatibility, but the lack of an objective voice on the matter makes evaluation difficult.

Although much of the crash incompatibility debate in recent years has centered around SUVs, the concept has been around far longer. When subcompact cars were introduced in the 1970s, there was a fear that incompatibilities of mass and design could lead to more serious injuries for drivers of these smaller, lighter vehicles. Crash incompatibility is an area of active study, although to date only a small fraction of crash tests focus on two-car crashes, and an even smaller proportion are properly designed to address incompatibility issues.

Oversteer is a phenomenon that can occur in an automobile which is attempting to turn. The car is said to oversteer when the rear wheels do not track behind the front wheels but instead slide out toward the outside of the turn. Oversteer can throw the car into a spin.

The tendency of a car to oversteer is affected by several factors such as mechanical traction, aerodynamics, suspension, and driver control. The driving technique called opposite lock is meant to cope in this circumstance.

Oversteer happens when the rear tires exceed the limits of their lateral traction during a cornering situation before the front tires do, thus causing the rear of the vehicle to head towards the outside of the corner. A more technical definition is that oversteer is the condition when the slip angle of the rear tires exceed that of the front tires.

Rear wheel drive cars are generally more prone to oversteer, in particular when applying power in a tight corner. This occurs because the rear tires must handle both the lateral cornering force and engine torque.

In modern race cars, especially open-wheel race cars, oversteering in high speed turns is caused mainly by aerodynamic configuration. In this respect, a heavier aerodynamic load on the front of the car relative to the rear causes it to oversteer. Oversteer in low speed turns is often reduced or eliminated electronically through traction control (if the sanctioning body allows their use). Nevertheless, the required front/rear balance to make the cars fast through corners is obtained by setting up the aerodynamics and balancing the suspension. The car’s tendency toward oversteer is generally increased by softening the front suspension or stiffening the rear suspension. Camber angles, ride height, and tire pressures can also be used to tune the balance of the car.

An oversteering car is alternatively referred to as ‘loose’ or ‘tail happy’.

Oversteer – Road Cars

Contrary to popular opinion, modern rear-wheel-drive cars are much more user-friendly in regard to oversteer. Their suspensions are balanced heavily toward understeer so that they are largely incapable of oversteering even if the driver attempts it on purpose. More powerful cars typically have on-board computer systems which can automatically brake the wheels or override the driver’s throttle inputs to prevent an oversteer condition (whether the driver wants it or not). This is because understeer is generally much safer for novice drivers, whereas oversteer is much more difficult to correct when one is not prepared for it. Many sports cars allow these systems to operate in more liberal modes or turned off completely by experienced drivers. Often this is performed by a special key sequence or other little known means so that inexperienced drivers will hopefully never try it.

The natural reaction of most drivers to the perception of loss of control during oversteer is to immediately lift their foot off the gas pedal. Unfortunately, this is exactly the wrong thing to do. Releasing the throttle pitches the car forward, causing a weight transfer towards the front of the car, thus reducing rear traction even further. The nose of the car rotates sharply toward the inside of the turn as it pitches into a spin.

Braking may or may not improve the situation. Most modern cars have a brake bias which tends to straighten out the car. However, there are two factors working against this. Most drivers must lift their foot from the gas pedal in order to press the brake, inducing the spin as described above. The second is that braking transfers more of the vehicle’s weight forward which tends to worsen oversteer. Even so, the brake bias may be enough to help, or at least not make it worse.

The correct reaction to oversteer is to gently steer into the slide and take the power away as needed without pitching the car forward. Indeed, cutting the power mid-corner can induce oversteer even in a front wheel drive vehicle. This is known as lift-off oversteer. “Trail braking,” or continuing to apply brake pressure after turning into a curve, can induce oversteer by transferring weight off of the rear tires, regardless of whether the car is front, rear or all-wheel drive. Note that in a front wheel drive car it is often better to simply accelerate hard to correct an oversteer slide.

Oversteer – Race Cars

A car that tends neither to oversteer nor understeer when pushed to the limit is said to have neutral handling. It seems intuitive that race drivers would prefer a slight oversteer condition to rotate the car around a corner, but this isn’t usually the case for two reasons. Accelerating early as the car passes the apex of a corner allows it to gain extra speed down the following straight. The driver who accelerates sooner and/or harder has a large advantage. The rear tires need some excess traction to accelerate the car in this critical phase of the corner, while the front tires can devote all their traction to turning. So the car must be set up with a slight understeer. Also, an oversteering car tends to be twitchy and ill tempered, making a race car driver more likely to lose control during a long race or when reacting to sudden situations in traffic.

Carroll Smith, in his book “Drive to Win”, provides a detailed explanation of why a fast race car must have a bit of understeer. Note that this applies only to pavement racing. Dirt racing is a different matter.

Even so, some successful race car drivers do prefer a bit of oversteer in their cars, preferring a car which is less sedate and more willing to turn into corners (or inside their opponents). It should be noted that the judgement of a car’s handling balance is not an objective one. Driving style is a major factor in the apparent balance of a car. This is why two drivers with identical cars on the same race team often run with rather different balance settings from each other. And both may call the balance of their cars ‘neutral’.

Drifting

The act of deliberately sending a car sideways through a series of corners is actually a popular form of motorsport that originated in Japan known as drifting.

A lawsuit is a civil action brought before a court in which the party commencing the action, the plaintiff, seeks a legal remedy. If the plaintiff is successful, judgment will be given in the plaintiff’s favour, and a range of court orders may be issued to enforce a right, impose a penalty, award damages, impose an injunction to prevent an act or compel an act, or to obtain a declaratory judgment to prevent future legal disputes.

It usually involves dispute resolution of private law issues between individuals, business entities or non-profit organizations. However, it may involve public law issues in those jurisdictions that enable the government to be treated as if it were a private party in a lawsuit (as plaintiff or defendant regarding an injury), or that provide the government with a civil cause of action to enforce certain laws rather than criminal prosecution. The conduct of a lawsuit is called litigation.

History of the Term “Lawsuit”

Today, lawyers in common law jurisdictions, particularly in the U.S., use the terms “lawsuit” and “civil action” synonymously, but this was not always the case. During the 18th and 19th centuries, it was common for lawyers to speak of bringing an “action” at law and a “suit” in equity. The unification of law and equity during the early 20th century led to the collapse of that distinction, so it became possible to speak of a “lawsuit.”

In England and Wales the term “claim” is far more common; the person initiating proceedings is called the claimant.

American terminology is slightly different, in that the term “claim” refers only to a particular count (or cause of action) in a lawsuit. Americans also use “claim” to describe a demand filed with an insurer or administrative agency. If the claim is denied, then the claimant (or policyholder or applicant) files a lawsuit with the courts and becomes a plaintiff.

In medieval times, both “action” and “suit” had the approximate meaning of some kind of legal proceeding, but an action terminated when a judgment was rendered, while a suit also included the execution of the judgment.

Torque steering is an effect in front wheel drive cars caused by large amounts of torque affecting steering in such a way as to make the front wheels “squirm” (oscillate) from side to side under heavy acceleration.

This effect is noticeable to the driver by the steering wheel being tugged back and forth by the wheels.

This effect can be engineered out of front wheel drive cars, using techniques such as advanced multi-link suspension systems.

Torque steer is mainly caused by uneven half-shafts between the transaxle and wheels. When excessive torque is applied, one shaft flexes more than the other, thus causing one wheel to momentarily spin slower than the other. This causes a steering effect. Ford engineered a simple method of eliminating (or at least reducing) torque steer by expanding the transaxle a little further to equalize the lengths of the halfshafts found on front wheel drive cars.

Any car with a high output (especially turbocharged) engine and front wheel drive is likely to exhibit some degree of torque steer.

A plaintiff, also known as a claimant or complainant, is the party who initiates a lawsuit (also known as an action) before a court. By doing so, the plaintiff seeks a legal remedy, and if successful, the court will issue judgment in favour of the plaintiff and make the appropriate court order (eg. an order for damages).

In some jurisdictions the commencement of a lawsuit is done by filing a summons, claim form and/or a complaint – these documents are known as pleadings – that set forth the alleged wrongs committed by the defendant or defendants with a demand for relief. In other jurisdictions the action is commenced by service of legal process by delivery of these documents on the defendant by a process server; they are only filed with the court subsequently with an affidavit from the process server that they had been given to the defendant(s) according to the rules of civil procedure.

Not all lawsuits are plenary actions, involving a full trial on the merits of the case. There are also simplified procedures, often called proceedings, in which the parties are termed petitioner instead of plaintiff, and respondent instead of defendant. There are also cases that do not technically involve two sides, such as petitions for specific statutory relief that require judicial approval; in those cases there are no respondents, just a petitioner.

The party to whom the complaint is against is the defendant; or in the case of a petition, a respondent. Case names are usually given with the plaintiff first, as in Plaintiff v. Respondent.

An automobile airbag, like this one in a crashed SEAT Ibiza car, deflates after 0.3 seconds.

An airbag, also known as a Supplementary/Secondary Restraint System (SRS) or as an Air Cushion Restraint System (ACRS), is a flexible membrane or envelope, inflatable to contain air or some other gas. Air bags are most commonly used for cushioning, in particular after very rapid inflation in the case of an automobile collision.

Airbag History

In 1952 the airbag was invented by John W. Hetrick and he patented the airbag the following year. It was an invention to help protect his own family using expertise from his naval engineering days.

There have been airbag-like devices for airplane as early as the 1940s, with the first patents filed in the 1950s.

The American inventor Allen Breed then developed a key component for automotive use – the ball-in-tube sensor for crash detection. He marketed this innovation first in 1967 to Chrysler. During this era, Americans were infrequent users of seat belts. A means of offering seat belt-like levels of occupant protection, to unbelted occupants, in a head-on collision was believed to be a valuable innovation.

Ford built an experimental fleet of cars with airbags in 1971. The first example of an airbag in a production car was in 1972 when the 1973 model Oldsmobile Toronado was released. In 1974, dual airbags were an option on several full-sized cars made by the Buick, Cadillac and Oldsmobile divisions. These devices did not meet with market acceptance.

The 1970s GM fleet of 10,000 airbag-equipped vehicles experienced seven fatalities. One death is now suspected to have been caused by the airbag. The crash severity was only moderate, and at the time a heart attack was suspected. The victim was cremated without an autopsy.

Then in 1980, Mercedes-Benz re-introduced the airbag in Germany as an option on its high end Mercedes-Benz W126, which also offered such other exotic options as hydropneumatic suspension. In the Mercedes system, the sensors would tighten the seat belts and then deploy the airbag on impact. From this point forward, the airbag was no longer marketed as a means of avoiding seat belts, but rather as a way to obtain an extra margin of occupant safety.

Airbags became common in the 1980s, with Chrysler and Ford introducing them in the mid-1980s. Ford made them standard equipment across its entire line in 1990. Autoliv, a worldwide leader in automotive safety systems, patented the side airbag and these safety systems began appearing in the mid-90s.

On July 11, 1984, the U.S. government required cars to have driver’s side air bags or automatic seat belts by 1989 (the automatic seat belt was a technology, now discarded, that “forced” motorists to wear seat belts). In 1998, dual front airbags were mandated by the National Highway Traffic Safety Administration (NHTSA), and de-powered, or second-generation air bags were also mandated. This was due to the injuries caused by first-generation air bags that were designed to be powerful enough to restrain people who were not wearing seat belts.

Despite the 1970s implementation of airbags in GM cars, many conventional automobiles did not even have them until the mid 1990s.

In 2006, Honda introduced the first motorcycle airbag safety system ever installed on a production motorcycle. The airbag was installed on its Gold Wing motorcycle.

Airbag Benefits

Air bags supplement the safety belt by reducing the chance that the occupant’s head and upper body will strike some part of the vehicle’s interior. They also help reduce the risk of serious injury by distributing crash forces more evenly across the occupant’s body.

“One recent study concluded that as many as 6,000 lives have been saved as a result of airbags.”

However, the exact number of lives saved is almost impossible to calculate.

Costs

Airbags cost about $500 per vehicle. If they are deployed in error or stolen, the motorist is required to repurchase them. Since they are an integral part of the vehicle design, it is not possible to retrofit airbags to a vehicle that does not have them.

Most manufacturers specify the replacement of undeployed airbags after, for example, 14 years to ensure their reliability in an accident. If the car is still on the road at this age, it would generally cost far more than the vehicle’s market value to have the airbags replaced.

Early Airbags: “Replacing” the Seat Belt

The standard shoulder belts were actually purposely omitted on the seventies cars with air bags since air bags were designed to replace seat belts in frontal impacts. The passenger side airbag on 1970s cars was located in the lower part of the dashpad and it also acted as a knee restraint. The lower part of the dash on the driver’s side was also different on cars with air bags, it was padded.

GM called this the Air Cushion Restraint System. The passenger side air bag in the seventies GM cars had two-stage deployment like newer air bags do.

The design is conceptually simple, accelerometers trigger the ignition of a gas generator propellant to very rapidly inflate a nylon fabric bag, which reduces the deceleration experienced by the passenger as they come to a stop in the crash situation. The bag has small vent holes to allow the propellant gas to be (relatively) slowly expelled from the bag as the occupant pushes against it.

Front air bags are not designed to deploy in side impact, rear impact or rollover crashes. Since air bags deploy only once and deflate quickly after the initial impact, they will not be beneficial during a subsequent collision. Safety belts help reduce the risk of injury in many types of crashes. They help to properly position occupants to maximize the air bag’s benefits and they help restrain occupants during the initial and any following collisions.

Although they were touted in the 1960s and 70s as a potential seat belt replacement, automobile airbags are now designed and sold as supplemental restraints; car designers have moved on from the initial view of the airbag as a seat belt replacement.

Airbag fatalities

Airbags involve the extremely rapid, violent deployment of a large object. While airbags can protect a person under the right circumstances, they can also injure or kill.

To protect occupants not wearing seat belts, U.S. airbag designs triggered much more quickly than airbags designed in other countries. As seat belt use in the U.S. climbed in the late 1980s and early 1990s, U.S. auto manufactures were required to adjust their designs.

Newer airbags trigger slightly less violent; nonetheless, passengers must remain at least 25 centimetres (10 in) from the bag to avoid injury from the bag in a crash.

In 1990, the first automotive fatality attributed to an airbag was reported, with deaths peaking in 1997 at 53 fatalities in the United States. TRW, an American corporation, produced the first gas-inflated airbag in 1994, with sensors and low-inflation-force bags becoming common soon afterwards. Dual-depth airbags appeared on passenger cars in 2005. By that time, deaths related to airbags had declined, with no adults deaths and 2 child deaths attributed to airbags that year. Injuries remain fairly common in accidents with an airbag deployment.

Smoking a pipe while driving should be avoided. If the airbag inflates and hits the pipe while it is in the mouth this may well be deadly, even if the impact is only moderate.

The increasing use of airbags has actually made rescue work for Firefighters, EMS and Police Officers more dangerous. Airbags can detonate long after the initial crash, injuring or even killing rescue workers who are inside the car. The addition of side impact airbags to the frame of the car has reduced the number of places that rescue workers can use hydraulic spreader-cutters (“the jaws of life”) or other similar cutting tools to remove the car roof, or doors safely. Every first responder should be properly trained on how to safely deactivate airbags or be aware of the potential hazards. Removing the car battery may be a good precaution.

In Europe the number of people not wearing their seatbelts is very small when compared to the United States, and Europeans are less likely to be obese. As a direct result of these two points, European airbags are less powerful than their American counterparts, and are therefore less likely to cause loss of life than the airbags fitted to American cars.

Airbag Design

An airbag system.

The air bag system consists of three basic parts: an air bag module, crash sensors and a diagnostic unit. Some systems may also have an on/off switch, which allows the air bag to be deactivated.

The air bag module contains both an inflator unit and the lightweight fabric air bag. The driver air bag module is located in the steering wheel hub, and the passenger air bag module is located in the instrument panel. When fully inflated, the driver air bag is approximately the diameter of a large beach ball. The passenger air bag can be two to three times larger since the distance between the right-front passenger and the instrument panel is much greater than the distance between the driver and the steering wheel.

The crash sensors are located either in the front of the vehicle and/or in the passenger compartment. Vehicles can have one or more crash sensors. The sensors are typically activated by forces generated in significant frontal or near-frontal crashes. Sensors measure deceleration, which is the rate at which the vehicle slows down. Because of this, the vehicle speed at which the sensors activate the air bag varies with the nature of the crash. Air bags are not designed to activate during sudden braking or while driving on rough or uneven surfaces. In fact, the maximum deceleration generated in the severest braking is only a small fraction of that necessary to activate the air bag system.

The diagnostic unit monitors the readiness of the air bag system. The unit is activated when the vehicle’s ignition is turned on. If the unit identifies a problem, a warning light alerts the driver to take the vehicle for examination of the air bag system. Most diagnostic units contain a device that stores enough electrical energy to deploy the air bag if the vehicle’s battery is destroyed very early in a crash sequence.

Some vehicles without rear seats, such as pickup trucks and convertibles, or with rear seats too small to accommodate rear-facing child safety seats, have manual on/off switches for the passenger air bag installed at the factory. These on/off switches for driver or passenger air bags may also be installed by qualified service personnel at the request of owners who meet government-specified criteria and who receive government permission.

Initially, most vehicles featured a single airbag, mounted in the steering wheel and protecting the driver of the car (who is the most at risk of injury). During the 1990s, airbags for front seat passengers, then separate side impact airbags placed between the door and occupants, became common.

Airbag Triggering Conditions

Airbags are typically designed to deploy in frontal and near-frontal collisions, which are comparable to hitting a solid barrier at approximately 8 to 14 miles per hour (13 to 23 km/h). Roughly speaking, a 14 mph (23 km/h) barrier collision is equivalent to striking a parked car of similar size across the full front of each vehicle at about 28 mph (45 km/h). This is because the parked car absorbs some of the energy of the crash, and is pushed by the striking vehicle. Unlike crash tests into barriers, real-world crashes typically occur at angles, and the crash forces usually are not evenly distributed across the front of the vehicle. Consequently, the relative speed between a striking and struck vehicle required to deploy the air bag, in a real-world crash, can be much higher than an equivalent barrier crash.

Because air bag sensors measure deceleration, vehicle speed and damage are not good indicators of whether an air bag should have deployed. Occasionally, air bags can deploy due to the vehicle’s undercarriage violently striking a low object protruding above the roadway surface. Despite the lack of visible front-end damage, high deceleration forces may occur in this type of crash, resulting in the deployment of the air bag.

The airbag sensor is a MEMS accelerometer, which is a small integrated circuit chip with integrated micromechanical elements. The microscopic mechanical element moves in response to rapid deceleration, and this motion causes a change in capacitance, which is detected by the electronics on the chip, which then sends a signal to fire the airbag. The most common MEMS accelerometer in use is the ADXL-50 by Analog Devices, but there are other MEMS manufacturers as well.

There was some work initially in mercury switches but they did not work very well. Before MEMS, the primary system used to deploy airbags was called a “rolamite”. A rolamite is a mechanical device, consisting of a roller suspended within a tensioned band. As a result of the particular geometry and material properties used, the roller is free to translate with very little friction or hysteresis. This device was developed at Sandia National Laboratories. The rolamite and similar macro-mechanical devices were used in air bags until the mid-1990s when they were universally replaced with MEMS.

Most air bags are designed to automatically deploy in the event of a vehicle fire when temperatures reach 300 to 400 degrees Fahrenheit (150 to 200 °C). This safety feature helps to ensure that such temperatures do not cause an explosion of the inflator unit within the air bag module.

Today, airbag triggering algorithms are becoming much more complex. They try to reduce useless deployments (for example, at low speed, no shocks should trigger the airbag to help reduce damage to the car interior in conditions where the seat belt would be an adequate safety device) and to adapt the deployment speed to the crash conditions. The algorithms are considered as very valuable intellectual property.

Airbag Deployment Mechanism

When there is a moderate to severe frontal crash that requires the frontal air bag to deploy, a signal is sent to the inflator unit within the air bag module. An igniter starts a chemical reaction, which produces a gas to fill the air bag, making the air bag deploy through the module cover. Some air bag technologies use nitrogen gas. A pellet of sodium azide (NaN3) is ignited. A rapid reaction occurs, generating nitrogen gas (N2) to fill the air bag. Potassium nitrate, and silicon dioxide are used in secondary and tertiary reactions to deal with the sodium that is liberated; first the potassium nitrate reacts with sodium, yielding sodium and potassium oxides and further gaseous nitrogen, then the oxides react with silicon dioxide, forming more or less inert glass particles. An alternative may use argon gas. Nitrogen and argon are both harmless. However, sodium azide as an aerosol is dangerous.

From the onset of the crash, the entire deployment and inflation process is faster than the blink of an eye. Airbags deploy in 15 milliseconds (0.015 seconds) for high speed crashes and in 25 milliseconds for low speed crashes (0.025 seconds). Because a vehicle changes speed so fast in a crash, air bags must inflate rapidly if they are to help reduce the risk of the occupant hitting the vehicle’s interior.

Once an air bag deploys, deflation begins immediately as the gas escapes through vents in the fabric. Deployment is frequently accompanied by the release of dust-like particles in the vehicle’s interior. Most of this dust consists of cornstarch or talcum powder, which are used to lubricate the air bag during deployment. Small amounts of sodium hydroxide may initially be present. This chemical can cause minor irritation to the eyes and/or open wounds; however, with exposure to air, it quickly turns into sodium bicarbonate (baking soda). Depending on the type of air bag system, potassium chloride (a table salt substitute) may also be present.

For most people, the only effect the dust may produce is some minor irritation of the throat and eyes. Generally, minor irritations only occur when the occupant remains in the vehicle for many minutes with the windows closed and no ventilation. However, some people with asthma may develop an asthmatic attack from inhaling the dust. With the onset of symptoms, asthmatics should treat themselves as advised by their doctor, then immediately seek medical treatment.

Once deployed, the air bag cannot be reused and should be replaced by an authorized service department. The vehicle can be driven after deployment, but there will be no supplemental restraint system until a replacement has been installed.

Air bags must inflate very rapidly to be effective, and therefore come out of the steering wheel hub or instrument panel with considerable force, generally at a speed over 180 mph (290 km/h). Because of this initial force, contact with a deploying air bag may cause injury. These air bag contact injuries, when they occur, are typically very minor abrasions or burns. The sound of air bag deployment is very loud, in the range of 165 to 175 decibels for 0.1 second. Hearing damage can result in some cases.

More serious injuries are rare; however, serious or even fatal injuries can occur when someone is very close to, or in direct contact with an air bag module when the air bag deploys. Such injuries may be sustained by unconscious drivers who are slumped over the steering wheel, unrestrained or improperly restrained occupants who slide forward in the seat during pre-crash braking, and even properly restrained drivers who sit very close to the steering wheel. Objects must never be attached to an air bag module or placed loose on or near an air bag module, since they can be propelled with great force by a deploying air bag, potentially causing serious injuries.

An unrestrained or improperly restrained occupant can be seriously injured or killed by a deploying air bag. The National Highway Traffic Safety Administration (NHTSA) recommends drivers sit with at least 10 inches (254 mm) between the center of their breastbone and the center of the steering wheel. Children under 12 should always be properly restrained in a rear seat. 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.

Advanced Airbag Design

Many advanced air bag technologies are being developed to tailor air bag deployment to the severity of the crash, the size and posture of the vehicle occupant, belt usage and how close that person is to the air bag module. Many of these systems will use multi-stage inflators that deploy less forcefully in stages in moderate crashes than in very severe crashes. Occupant sensing devices let the air bag diagnostic unit know if someone is occupying a seat in front of an air bag, whether the person is an adult or a child, whether a seat belt or child safety seat is being used and whether the person is forward in the seat and close to the air bag module. Based on this information and crash severity information, the air bag is deployed at either a high force level, a less forceful level or not at all.

Many new vehicles are also equipped with side air bags. While there are several types of side air bags, all are designed to reduce the risk of injury in moderate to severe side impact crashes. These air bags are generally located in the outboard edge of the seat back, in the door or in the roof rail above the door.

Seat and door-mounted air bags all provide upper body protection. Some also extend upwards to provide head protection. Two types of side air bags, known as inflatable tubular structures and inflatable curtains, are specifically designed to reduce the risk of head injury and/or help keep the head and upper body inside the vehicle. A few vehicles are now being equipped with a different type of inflatable curtain designed to help reduce injury and ejection from the vehicle in rollover crashes.

An automobile is a wheeled passenger vehicle that carries its own motor. Different types of automobiles include cars, buses, trucks, and vans. Some include motorcycles in the category, but cars are the most typical automobiles. The term automobile is derived from Greek auto (“self”) and Latin mobilis (“movable”), referring to the fact that it “moves by itself”. Earlier terms for automobile include motorwagen, and horseless carriage. Although the term “car” is presumed to be derived through the shortening of the term “carriage”, the word has its origin before 1300 A.D. in English as, “carr”—derived from similar words in French and much earlier Greek words—for a vehicle that moves, especially on wheels, that was applied to chariots, small carts, and later to carriages that carried more people and larger loads. As of 2005 there were 600 million cars worldwide (93 cars per 1,000 persons).

The automobile was hailed as an environmental improvement over horses when it was first introduced in the 1880s. Before its introduction, in New York City alone, more than 1,800 tons of manure had to be removed from the streets daily, although the manure was used as natural fertilizer for crops and to build top soil. In 2006, the automobile is recognized as one of the primary sources of world-wide air pollution and a cause of substantial noise pollution and adverse health effects.

Automobile History

Replica of the Benz Patent Motorwagen built in 1885.

The automobile powered by the Otto gasoline engine was invented in Germany by Karl Benz in 1885. Benz was granted a patent dated 29 January 1886 in Mannheim for that automobile. Even though Benz is credited with the invention of the modern automobile, several other German engineers worked on building automobiles at the same time. In 1886, Gottlieb Daimler and Wilhelm Maybach in Stuttgart patented the first motor bike, built and tested in 1885, and in 1886 they built a converted horse-drawn stagecoach. In 1870, German-Austrian inventor Siegfried Marcus assembled a motorized handcart, though Marcus’s vehicle didn’t go beyond the experimental stage.

Production of Automobiles Begins

The internal-combustion-engine automobile really can be said to have begun in Germany with Karl Benz in 1885-1886, and Gottlieb Daimler between 1886-1889, for their vehicles were successful, they went into series-production (albeit in modified form), and they inspired others.

Karl Benz began to work on new engine patents in 1878. First, he concentrated all his efforts on creating a reliable two-stroke gas engine, based on Nikolaus Otto’s design of the four-stroke engine. A patent on the design by Otto had been declared void. Karl Benz finished his engine on New Year’s Eve and was granted a patent for it in 1879. Karl Benz built his first three-wheeled automobile in 1885 and it was granted a patent in Mannheim, dated January of 1886. This was the first automobile designed and built as such, rather than a converted carriage, boat, or cart. Among other items Karl Benz invented for the automobile are the carburetor, the speed regulation system known also as an accelerator, ignition using sparks from a battery, the spark plug, the clutch, the gear shift, and the water radiator. He built improved versions in 1886 and 1887 and—went into production in 1888—the world’s first automobile put into production. His wife, Bertha, made significant suggestions for innovation that he included in that model. Approximately twenty-five were built before 1893, when his first four-wheeler was introduced. They were powered with four-stroke engines of his own design. Emile Roger of France, already producing Benz engines under license, now added the Benz automobile to his line of products. Because France was more open to the early automobiles, in general, more were built and sold in France through Roger, than Benz sold initially from his own factory in Germany.

Gottlieb Daimler, in 1886, fitted a horse carriage with his four-stroke engine in Stuttgart. In 1889, he built two vehicles from scratch as automobiles, with several innovations. From 1890 to 1895 about thirty vehicles were built by Daimler and his innovative assistant, Wilhelm Maybach, either at the Daimler works or in the Hotel Hermann, where they set up shop after having a falling out with their backers. These two Germans, Benz and Daimler, seem to have been unaware of the early work of each other and worked independently. Daimler died in 1900. During the First World War, Benz suggested a co-operative effort between the companies the two founded, but it was not until 1926 that the companies united under the name of Daimler-Benz with a commitment to remain together under that name until the year 2000.

In 1890, Emile Levassor and Armand Peugeot of France began series-producing vehicles with Daimler engines, and so laid the foundation of the motor industry in France. They were inspired by Daimler’s Stahlradwagen of 1889, which was exhibited in Paris in 1889.

The first American automobile with gasoline-powered internal combustion engines supposedly was designed in 1877 by George Baldwin Selden of Rochester, New York, who applied for a patent on an automobile in 1879. Selden didn’t build a single automobile until 1905, when he was forced to do so, due to a lawsuit threatening the legality of his patent because the subject had never been built. Construction is required to demonstrate the feasibility of the design and validate the patent, otherwise the patent may be voided. After building the 1877 design in 1905, Selden received his patent and later sued the Ford Motor Company for infringing upon his patent. Henry Ford was notorious for opposing the American patent system and Selden’s case against Ford went all the way to the Supreme Court, which ruled that Ford, and anyone else, was free to build automobiles without paying royalties to Selden, since automobile technology had improved so significantly since the design of Selden’s patent, that no one was building according to his early designs.

Meanwhile, notable advances in steam power evolved in Birmingham, England by the Lunar Society. It was here that the term horsepower was first used. It also was in Birmingham that the first British four-wheel petrol-driven automobiles were built in 1895 by Frederick William Lanchester. Lanchester also patented the disc brake in that city.

Automobile Safety

Automobile accidents are almost as old as automobiles themselves. Joseph Cugnot crashed his steam-powered “Fardier” against a wall in 1771. One of the earliest recorded automobile fatalities was Mary Ward, on 1869-08-31 in Parsonstown, Ireland, an early victim in the United States was Henry Bliss on 1899-09-13 in New York City, NY.

Cars have two basic safety problems: They have human drivers who make mistakes, and the wheels lose traction near a half gravity of deceleration. Automated control has been seriously proposed and successfully prototyped. Shoulder-belted passengers could tolerate a 32G emergency stop (reducing the safe intervehicle gap 64-fold) if high-speed roads incorporated a steel rail for emergency braking. Both safety modifications of the roadway are thought to be too expensive by most funding authorities, although these modifications could dramatically increase the number of vehicles that could safely use a high-speed highway.

Early safety research focused on increasing the reliability of brakes and reducing the flammability of fuel systems. For example, modern engine compartments are open at the bottom so that fuel vapors, which are heavier than air, vent to the open air. Brakes are hydraulic so that failures are slow leaks, rather than abrupt cable breaks. Systematic research on crash safety started in 1958 at Ford Motor Company. Since then, most research has focused on absorbing external crash energy with crushable panels and reducing the motion of human bodies in the passenger compartment.

There are standard tests for safety in new automobiles, like the EuroNCAP and the US NCAP tests. There are also tests run by organizations backed by the insurance industry such as the Insurance Institute for Highway Safety (IIHS).

Despite technological advances, there is still significant loss of life from car accidents: About 40,000 people die every year in the U.S., with similar figures in Europe. This figure increases annually in step with rising population and increasing travel if no measures are taken, but the rate per capita and per mile travelled decreases steadily. The death toll is expected to nearly double worldwide by 2020. A much higher number of accidents result in injury or permanent disability. The highest accident figures are reported in China and India. The European Union has a rigid program to cut the death toll in the EU in half by 2010 and member states have started implementing measures.

Future of the Car

Toyota FCHV (Fuel Cell Hybrid Vehicle). A fuel cell hybrid car which runs from the hydrogen which Toyota developed, 2005.

In order to limit deaths, there has been a push for self-driving automobiles. There have been many notable efforts funded by the National Highway Traffic Safety Administration (NHTSA), including the many efforts by the NavLabgroup at Carnegie Mellon University. Recent efforts include the highly publicized DARPA Grand Challenge race.

A current invention is ESP by Bosch that is claimed to reduce deaths by about 30% and is recommended by many lawmakers and carmakers to be a standard feature in all cars sold in the EU. ESP recognizes dangerous situations and corrects the drivers input for a short moment to stabilize the car.

Relatively high transportation fuel prices do not completely stop car usage but makes it significantly more expensive. One environmental benefit of high fuel prices is that it incentivises the production of more efficient (and hence less polluting) car engines and designs and the development of alternative fuels. In the beginning of 2006, 1 liter of gas costs approximately $1.60 in Germany and other European countries, and one U.S. gallon of gas costs nearly $3.00. With fuel prices at these levels there is a strong incentive for consumers to purchase lighter, smaller, more fuel-efficient cars. Nevertheless, individual mobility is highly prized in modern societies so the demand for automobiles is inelastic. Alternative individual modes of transport, such as Personal Rapid Transit (PRT), could make the automobile obsolete if they prove to be cheaper and more energy efficient.

Hydrogen cars, driven either by a combination of fuel cells and an electric motor, or alternatively, a conventional combustion engine, are widely mooted to replace fossil fuel powered cars in a few decades. Some obstacles to a mass market of hydrogen cars include: the cost of hydrogen production by electrolysis, which is inefficient and requires an inexpensive source of electrical energy to be economical, the difficulty of storing hydrogen either in its gaseous or liquid (cryogenic) form, and the lack of a hydrogen transport infrastructure such as pipelines and filling stations. Hydrogen has a much higher energy density than gasoline or diesel. It is thought to become cheaper with mass production, but because its production is overall energy inefficient and requires other sources of energy, including fossil, it is unlikely to be a cheaper fuel than gasoline or diesel today. Also, its combustion produces only water vapour (a greenhouse gas) and virtually no local pollutants such as NOx, SOx, benzene and soot. BMW’s engineering team promises a high horsepower hydrogen fuel engine in it’s 7-series sedan before the next generation of the car makes its debut.

The electric car in general appears to be a way forward in principle; electric motors are far more efficient than internal combustion engines and have a much greater power to weight ratio. They also operate efficiently across the full speed range of the vehicle and develop a lot of torque at zero speed, so are ideal for cars. A complex drivetrain and transmission would not be needed. However, despite this the electric car is held back by battery technology – so far a cell with comparable energy density to a tank of liquid fuel is a long way off, and there is no infrastructure in place to support it. A more practical approach may be to use a smaller internal combustion (IC) engine to drive a generator- this approach can be much more efficient since the IC engine can be run at a single speed, use cheaper fuel such as diesel, and drop the heavy, power wasting drivetrain. Such an approach has worked very well for railway locomotives, but so far has not been scaled down for car use.

Recently the automobile industry has determined that the biggest potential growth market (in terms of both revenue and profit), is software. Cars are now equipped with a stunning array of software; from voice recognition and vehicle navigation systems, vehicle tracking system like ESITrack to in-vehicle distributed entertainment systems (DVD/Games), to telematics systems such as GMs Onstar not to mention the control subsystems. Software now accounts for 35% of a cars value, and this percentage is only going to get larger. The theory behind this is that the mechanical systems of automobiles are now essentially a commodity, and the real product differentiation occurs in the software systems. Many cars are equipped with full blown 32bit real-time memory protected operating systems such as QNX.

A new invention by Carmelo Scuderi, the Scuderi Split Cycle Engine claims to improve the efficiency of an engine from 33.2% to 42.6%. In addition, toxic emissions are claimed to be reduced by as much as 80%.

Hypothetical driverless cars and flying cars have been proposed for decades, but for now the costs would outweigh the benefits (traffic overhaul and control, fuel and operating costs, the development of widely available driverless and flying cars itself, and the technology required for such vehicles which is currently out of reach). Thus driverless and especially flying cars still are an idea widely associated with science fiction.

A Contact patch is the term applied to the portion of a vehicle’s tire that is in actual contact with the road surface. The shape of a tire’s contact patch can have a great effect on the handling of the vehicle to which it is fitted. Specifically, for the type of wide tire fitted to many modern performance cars, a contact patch that is wider than it is long will increase the tendency for the vehicle to ‘tramline’ or follow uneven road contours. Furthermore, in front wheel drive cars, the offset between the centroid of the contact patch and the point about which the wheel steers can lead to a condition known as torque steer.

Proper Inflation

With normal street tires on an automobile the contact patch will remain uniform across the tread of the tire. If the tire is over-inflated the tire will tend to bulge in the center of the tread which will lift the edges off the pavement. This can decrease the handling performance of the vehicle and also decrease the life of the tire. Prolonged use of a tire which is over-inflated will cause the tread in the center to wear away faster than the tread on the edges.

An under-inflated tire can have negative effects as well. In this case the center of the tread will not make as much contact with the road surface and the edges of the tread will wear down faster because the sidewalls of the tire will push the edges into the pavement.

One method of checking for proper inflation is to find a long stretch of pavement such as an empty parking lot and then draw a line across the tread with chalk. Then simply drive straight across the parking lot. If the entire line of chalk has rubbed off, the tire is properly inflated. If the center of the line is rubbed off but the ends are still present, the tire is over-inflated. On the other hand, if the line is rubbed off at the ends but is still present in the center of the tread, the tire is under-inflated.