Vehicle dynamics and safety systems

The technology in cars and motorcycles is changing all the time, below are some of the features available. Make yourself familiar with the systems in the vehicle you are about to drive or ride BEFORE the wheels turn!


Front airbags have been standard on all new cars since 1998 and light trucks since 1999. Most vehicles had them even before then. Crash sensors connected to an onboard computer detect a frontal collision and trigger the bags. The bags inflate in a few milliseconds—the blink of an eye—then immediately start deflating.

While airbags have saved thousands of lives, they also have the potential to cause injury or even death to children or to occupants who aren’t using a seatbelt. Children under twelve should be seated in the rear in an appropriate restraint system and rear-facing child seats should never be installed in front seats equipped with airbags.

Adaptive, or dual-stage front airbags, introduced in 2003, became standard across the board by the 2007 model year. Most airbag systems now detect the presence, weight, and seat position for the driver and front passenger, and deactivate or de-power front airbags as appropriate to minimise the chance of injury to drivers positioned close to the wheel, out-of-position occupants, or children.

Side airbags. Torso protecting side-impact airbags for front-seat passengers are also nearly universal, and some automakers offer side airbags for rear-seat passengers, as well. Side airbags are small cushions that pop out of the door trim or the side of the seat. They help protect the torso, but most aren’t effective in protecting the head. Nearly all new models today also include additional “side curtain” bags that deploy from above the windows and cover both front and rear side windows to prevent occupants from hitting their heads and to shield them from flying debris. A curtain bag often also stays ‘inflated’ longer in most cases to also keep people from being ejected during a rollover or a high-speed side crash. The better head-protection systems deploy the side-curtain bags if the system detects that the vehicle is beginning to roll over.

Anti-lock brakes (ABS)

Before anti-lock brakes came along, it was all too easy to lock up the wheels (stop them from turning) during hard braking. Sliding the front tires makes it impossible to steer, particularly on slippery surfaces. ABS prevents this from happening by using sensors at each wheel and a computer that maximises braking action at each individual wheel to prevent lock-up. ABS allows the driver to retain steering control while braking, so that the car can be manoeuvred around an obstacle, if necessary. Some drivers, unaccustomed to ABS actuation, may be alarmed as the pulsing sensation conveyed through the brake pedal and chattering at the wheels when used. Not to worry. This is the system rapidly applying the brakes to provide maximum power and control. The trick is to push hard on the pedal and let the system do its job.

Traction control

This electronically controlled system limits wheel spin during acceleration so that the drive wheels have maximum traction. It’s particularly useful when starting off in wet or icy conditions, and/or launching with a high-horsepower engine. Some traction-control systems operate only at low speeds, while others work at all speeds.

Most traction-control systems use the car’s anti-lock brake system to momentarily brake a spinning wheel. This routes power to the opposite drive wheel. Systems on some automatic vehicles may also throttle back the engine, and up-shift the transmission, to prevent wheel spin.

Electronic stability control

Electronic stability control (ESC) takes traction control a step further. This system helps keep the vehicle on its intended path during a turn, to avoid sliding or skidding. It uses a computer linked to a series of sensors—detecting wheel speed, steering angle, sideways motion, and yaw (rotation). If the car drifts outside the driver’s intended path, the stability-control system momentarily brakes one or more wheels and, depending on the system, reduces engine power to pull the car back on course.

ESC is especially helpful with tall, top-heavy vehicles like sport-utilities and pickups, where it can also help keep the vehicle out of situations where it could roll over.

Electronic stability control became standard equipment on all cars with the 2012 model year. It started on luxury cars years ago and then migrated to other vehicles. It became especially commonplace on Sports Utility Vehicles (SUVs). Car manufacturers each tend to have a proprietary name for their stability control systems, as listed below. If in doubt whether a used car has it, find out before you buy. It is however important to note that if you take any corner too fast could push the vehicle beyond the system’s limits. So don’t just speed into a bend and expect the system to bail you out.

Safety-belt features

While the seatbelt is arguably the single most important piece of safety equipment, enhanced features help seatbelts do their job more effectively.

Seatbelt pre-tensioners instantly retract the belts to take up slack during a frontal impact. This also helps position occupants properly to take full advantage of a deploying air bag. Force limiters, a companion feature to pre-tensioners, manage the force that the shoulder belt builds up on the occupant’s chest. After the pre-tensioners tighten it, force limiters let the belt play back out a little to reduce the force.

Some models offer inflatable safety belts in the rear seat that further reduce the force of the belts themselves on rear passengers in an accident and spread those forces over a wider area—a particular concern with more fragile occupants, such as children or the elderly.

Adjustable upper fixing points for the shoulder belts can make a meaningful safety difference. Adjustable fixing points help position the belt across the chest instead of the neck to prevent neck injuries. They also can help keep the belt from pulling down on a tall person’s shoulder, making it more comfortable and thereby encouraging its use.

Using a child car seat or booster seat

The rules are different in different countries, below are the rules governing the UK (from

Children must normally use a child car seat until they’re 12 years old or 135 centimetres tall, whichever comes first.

Children over 12 or more than 135 cm tall must wear a seat belt.

You can choose a child car seat based on your child’s height or weight.

Height-based seats

Height-based seats are known as ‘i-Size’ seats. They must be rear-facing until your child is over 15 months old. Your child can use a forward-facing child car seat when they’re over 15 months old.

You must check the seat to make sure it’s suitable for the height of your child.

Only EU-approved height-based child car seats can be used in the UK. These have a label showing a capital ‘E’ in a circle and ‘R129’.

Weight-based seats

The seat your child can use (and the way they must be restrained in it) depends on their weight.

Only EU-approved weight-based child car seats can be used in the UK. These have a label showing a capital ‘E’ in a circle and ‘ECE R44’.

You may be able to choose from more than one type of seat in the group for your child’s weight.

Child’s weight

0kg to 10kg Lie-flat or ‘lateral’ baby carrier, rear-facing baby carrier, or rear-facing baby seat using a harness

0kg to 13kg Rear-facing baby carrier or rear-facing baby seat using a harness

9kg to 18kg Rear or forward-facing baby seat using a harness or safety shield

15kg to 25kg Rear or forward-facing child car seat (high-backed booster seat or booster cushion) using a seat belt, harness, or safety shield

22kg to 36kg Rear or forward-facing child car seat (high-backed booster seat or booster cushion) using a seat belt, harness, or safety shield

Manufacturers can now only make booster cushions approved as group 3. This won’t affect any existing booster cushions in group 2, and you’ll still be able to use them.

Fitting a child car seat

You must only use a child car seat if your car’s seat belt has a diagonal strap, unless the seat is either:

  • specifically designed for use with a lap seat belt
  • fitted using ISOFIX anchor points

You must also:

  • deactivate any front airbags before fitting a rear-facing baby seat in a front seat
  • not fit a child car seat in side-facing seats

The Child Car Seats website has information on how to choose a seat and travel safely with children in cars.

Children with disabilities or medical conditions

The same rules apply for children with disabilities or medical conditions, but they can use a disabled person’s seat belt or a child restraint designed for their needs.

A doctor can issue an exemption certificate if a child is unable to use a restraint or seat belt because of their condition.

Newer safety features – accident-avoidance systems

Brake assist

Brake assist detects when a driver initiates a panic stop (as opposed to ordinary gradual stops) and applies the brakes to maximum force. In conjunction with anti-lock brakes, the system enables threshold braking without locking up the wheels. Studies have shown that most drivers, even in panic stops, don’t apply the brakes as hard as they could, so Brake Assist intervenes to reach the shortest possible stopping distance.

Forward-collision warning (FCW)

Forward-collision warning uses cameras, radar or laser (or some combination thereof) to scan for cars ahead and alert the driver if they are approaching a vehicle in their lane too fast and a crash is imminent. Most systems alert the driver with some sort of visual and or audible signal to a potential crash, allowing time for you to react.

Automatic emergency braking (AEB)

These systems add to the benefits of forward-collision warning. AEB will sense a potential collision and if you don’t react in time, the car will initiate automatic braking.

Pedestrian detection

This system uses the features of forward collision warning and automatic emergency braking to help protect pedestrians. The vehicle’s camera(s) or radar are looking for a pedestrian in the vehicle’s path. Some systems will alert the driver with an audible or visual alert and some will even start automatic emergency braking if a collision is deemed high.

Adaptive cruise control

Adaptive cruise uses lasers, radar, cameras, or a combination of these systems to keep a constant distance between you and the car ahead, automatically maintaining a safe following distance. If highway traffic slows, some systems will bring the car to a complete stop and automatically come back to speed when traffic gets going again, allowing the driver to do little more than pay attention and steer. Some vehicles equipped with lane keeping assist will also allow the car to stay within the lane markings.

Blind-spot warning (BSW)

Using radar or cameras, this system illuminates a light or icon in or adjacent to the outside mirrors to warn that another vehicle is lurking in the lane beside, possibly hidden in your car’s blind spot. Many systems also sound an audible warning if you attempt to move over anyway or operate your turn signal indicating that you’re going to. More advances systems can also brake or steer the vehicle back towards the center of the lane. Also effective are outside mirrors with a small convex section for a wide-angle rearward view.

Rear cross-traffic alert

These systems sense traffic that may cross your path as you reverse, which can be helpful when you are backing out of a parking space or driveway. Some systems will automatically brake for the driver to avoid an object.

Lane-departure warning (LDW)

This alerts you if you steer your car out of its lane without the turn signals activated. Using a camera or lasers to monitor lane markers, the LDW may sound a chime, blink a dashboard telltale, and/or vibrate the steering wheel or seat.

Lane assist (LA)

In addition to sensing when you leave your lane, this technology will introduce a mild steering input to put you back into your lane.

Active head restraints

Active head restraints move up and forward in a rear crash to cradle the head and absorb energy in an effort to mitigate whiplash injury.

Reversing cameras

Starting in the 2018 model year all light-duty vehicles will come with standard rear-view cameras.This camera-based assistance system is activated when the vehicle is placed in reverse. The rear view is displayed in a centre console screen or rear-view mirror. Mostly used as a parking aid by providing a bumper-level view aft, a backup camera can also assist with spotting a child or pedestrian concealed in the blind zone immediately behind the vehicle.. A recommended convenience, this is a safety feature whose value is made apparent every time you drive. Plus, some more advanced systems give a 360 degree view around the vehicle.

Parking assist systems

These are sensors embedded in the front, rear, or both bumpers that alert you—at parking speeds—that light poles, walls, shrubbery and other obstacles are getting close.

Automatic main beam

This function automatically switches from low to high beam and back again, for improved nighttime visibility as conditions warrant.

Tyre-pressure monitors

Underinflated tyres can hurt handling and fuel economy. They can even lead to a blowout as underinflated tyres are more susceptible to damage and wear. A tyre can lose air through the rubber and does so slowly so that many drivers don’t notice. The type of tyre-pressure monitor we favour measures tire pressure directly. Others gauge air loss indirectly by using sensors to count wheel revolutions.


Combining cellular telephone and Global Positioning Satellite (GPS) technology, several major car manufacturers are offering an automated service that provides a high level of security and convenience. Systems include GM OnStar, BMW Assist, Hyundai Bluelink, Kia UVO, Lexus Safety Connect, Mercedes-Benz’s mBrace, and Toyota Safety Connect. These systems allow the driver to communicate with a central dispatch centre at the touch of a button. This centre knows the location of the vehicle and can provide route directions or emergency aid on request. If an air bag deploys, the system automatically notifies the dispatch centre, locates the vehicle, and summons emergency service, if the driver does not respond to a phone-based inquiry. Plus ,most manufactures have smartphone apps that will start,unlock your car and beep the horn to help find your lost car in that large parking lot.

The cost of telematics systems is built into the price of most vehicles that have them, but a monthly subscription fee, typically $10 to $20, is usually required. Smartphone apps usually require a subscription fee as well.

Lessons in this course: