Active safety features: Active safety features are designed to prevent or mitigate crashes by detecting potentially dangerous situations (for example, wheel lock or extreme side-to-side movement) and automatically taking corrective action. Examples of active safety features include electronic stability control, brake assist, and anti-lock braking systems.
Adaptive Cruise Control: Introduced in the early 2000s, adaptive cruise control is a sophisticated modification of existing cruise control systems. Whereas previous cruise control systems would only maintain the vehicle’s speed, adaptive cruise control systems use road-scanning technology to automatically slow the vehicle down if traffic ahead is decelerating. Then, once traffic ahead picks up speed, the adaptive cruise control system will return the vehicle to its pre-deceleration speed of travel.
Adaptive Headlights: First available in the early 2000s, adaptive headlights are designed to light up the roadway around a corner or over a hill when driving in low-light conditions such as dusk, sunrise, or during the night. Vehicles with adaptive headlights are equipped with sensors that detect the degree to which a vehicle is turning a corner or ascending a hill and then direct small motors attached to the headlights to turn the beams to the left, right, up, or down according to the direction of the vehicle.
Airbags: First introduced in vehicles in the early 1970s, airbags are large fabric sacs designed to inflate immediately after a crash. The purpose of airbags is to protect occupants from hitting the hard interior of the vehicle. Airbags can be installed in many places within the vehicle, including the dashboard, steering column, side-panels, and around the knees. The inflation of an airbag happens very quickly, and can cause minor injuries to vehicle occupants who are unbelted or who aren’t properly positioned within the vehicle.
All-Wheel Drive (AWD): Useful in adverse weather or other low-friction conditions, all-wheel drive vehicles are able to deliver engine torque to each wheel individually, as opposed to sets of wheels. This capability contrasts with two-wheel drive (engine power is sent only to either the front or back set of wheels) and with four-wheel drive (engine power is sent to both front and back sets of wheels). When driven safely, all-wheel drive vehicles can make the most effective use of all available traction, and have the lowest risk of slipping or skidding.
Anti-Lock Braking Systems (ABS): Widely available as early as the 1970s, the function of ABS is to prevent wheels from locking during an episode of heavy braking, thereby allowing the driver to retain steering control of the vehicle while braking. ABS prevents wheels from locking by releasing and applying the brake in rapid succession to wheels that the system senses are in danger of locking.
Behavioural Adaptation: In the context of road safety, behavioural adaptation refers to “unintended behaviour that arises following a change in the road traffic system that has negative consequences for safety” . Examples of possible behavioural adaptations include driving faster in inclement weather because the vehicle has traction control, driving distracted because the vehicle has adaptive cruise control, or driving while impaired because the vehicle has a lane-departure warning system.
Blood Alcohol Concentration (BAC): Blood alcohol concentration (BAC) is a generally used as a metric for determining level of alcohol intoxication. A person’s BAC is typically expressed as a percentage of alcohol in the blood. For example, a BAC of 0.08% means that 0.08% of the total volume of the blood is alcohol.
Brake Assist: Many drivers do not apply enough brake pressure in emergency braking situations, thereby failing to stop their vehicle as quickly as they could. Brake assist is designed to make emergency braking as effective as possible by recognizing the signs of panic braking and boosting the brake force. When a driver pushes the brake pedal hard enough and fast enough to signal an emergency, brake assist will activate and apply all the brake force available in order to stop the vehicle as quickly as possible.
Brake Lock: Brake lock (or wheel lock) occurs when a driver applies the brakes so hard that the wheels stop spinning. The vehicle will usually skid, and the driver may hear an accompanying screeching sound. Of concern, when wheels stop rotating, the driver no longer has steering control over the vehicle.
Brake Override: Brake override is a failsafe safety feature designed to prevent unintended accelerations. When the gas and brake pedal are pushed down simultaneously and in the proper sequence, brake override eliminates the influence of the accelerator pedal and slows the vehicle safely to a stop.
Circadian Rhythm - Connected Vehicle Technology
Circadian Rhythm: The circadian rhythm refers to a roughly 24-hour cycle of physiological processes undergone by all living creatures. The body’s natural sleep-wake cycle operates within this rhythm. This is why people tend to feel drowsy around the same times throughout the day – in the early afternoon and in the evening. Night shifts, staying up late, and international travel can all disrupt the body’s natural circadian rhythm.
Connected Vehicle Technology: Connected vehicle technology is an intelligent transport system that may represent the future of vehicle safety. A completely new way of looking at driving, connected vehicle technology makes use of road scanners, sensors, intelligent infrastructure, and complete electronic integration to connect difference vehicles together such that they might be able to “communicate” with one another. For example, a vehicle could warn its driver about road conditions ahead, could inform the driver of how much space exists around the vehicle, or offer an alternative route that avoids construction slow-downs. In addition, infrastructure intelligence could mean that traffic lights could be cycled to allow emergency vehicles to proceed through while all other traffic is stopped.
Distracted Driving: Drivers are distracted whenever some or all of their attention is diverted away from the driving task. Objects, people, tasks, and events can all be a source of distraction, which can stem from inside the vehicle (e.g., changing the radio station), or outside the vehicle (e.g., looking at a low-flying airplane).
Driver Alcohol Detection System for Safety (DADSS): Driver alcohol detection systems are designed to help prevent people who have consumed an unsafe amount of alcohol from driving their vehicles. Unlike interlock ignition devices, which may be installed in vehicles after the driver receives an impaired driving conviction, DADSS are non-intrusive devices that measure the amount of alcohol present in any driver’s exhaled breath. Some DADDSSs measure alcohol levels through the skin. At the foundation of any DADSS is the ability to detect the presence of alcohol without requiring that drivers blow into a sensor.
Driver Assistance Technology: Driver assistance technology refers to vehicle features that help drivers with routine driving tasks like driving at night, maintaining proper distance from other vehicles, and monitoring road users in the blind spot. Examples of driver assistance technology include adaptive headlights, adaptive cruise control, and lane departure warning systems.
Drive-By-Wire: Drive-by-wire refers to vehicles that operate using a fully integrated electronic system. Drive-by-wire systems are the modern replacement for exclusively mechanical-hydraulic vehicles. The computer technology inherent in drive-by-wire systems allows for the unprecedented installation and interconnection of a variety of vehicle parts and features.
The Doppler Effect: The Doppler effect is the change in frequency of a wave (sound or light) experienced by an observer relative to its moving source. One of the most routine examples of the Doppler effect occurs when the frequency of the sound of an approaching vehicle is higher, and then drops to a lower frequency when the vehicle is travelling farther away. The phenomena is sometimes referred to as Doppler shift, highlighting the way the forward or backward travel of a wave-emitting source causes shifts in the frequency of the waves as experienced by an observer.
Drowsiness: Drowsiness is manifested primarily by the desire to sleep. People can feel drowsy for a number of reasons, including lack of adequate sleep, the influence of medication, or the effects of sleep disorders. Drowsiness might also occur at regular intervals in the day and at night, according to the body’s natural circadian rhythm. Symptoms of drowsiness include yawning, lethargy, and falling asleep.
Electronic Brake-Force Distribution (EBFD): Electronic brake-force distribution is designed to make braking as effective as possible by redistributing brake-force according to which wheels have the best chance of stopping the vehicle. When a drivers brakes, the inertia of the vehicle results in more of the vehicle’s weight on the front wheels. To compensate for this, EBFD allocates more brake-force to the front wheels and less to the back wheels, which brake less effectively when the vehicle’s weight is pushed forward.
Electronic control unit (ECU): An electronic control unit is the central processor of a drive-by-wire vehicle system. Generally, information from various sensors positioned around the vehicle is compiled in the ECU. Then, the ECU issues commands based on this information. For example, the ECU in a vehicle with brake override might order the brake pedal to override the gas pedal, if both are pushed down simultaneously.
Electronic Stability Control (ESC): Heralded as the most important advancement in vehicle safety since seatbelts, ESC is designed to enhance vehicle stability by monitoring the vehicle’s side-to-side motion and applying brakes to individual wheels in cases of understeering or oversteering. ESC has been shown to dramatically reduce the risk of involvement in loss-of-control crashes and rollover crashes.
Fatigue: Fatigue is defined as the disinclination to continue participating in the task at hand. Even if a driver has had a good night’s rest and is not feeling tired per se, the act of driving can induce fatigue, particularly if the drive is long in duration and takes place in a relatively unchanging setting (e.g., a highway). Drivers who are fatigued will experience symptoms of tiredness, such as yawning, heavy eyelids, and potentially falling asleep.
Forward Collisions Warning (FCW) Systems: Recently available in the economy vehicle market, forward collision waning systems are designed to warn drivers if they are about to hit an object on the road ahead. These systems use audible, visual, and haptic warnings to communicate the danger of an impending collision. Some systems will also apply the brakes if the driver does not respond to the alarm. Due perhaps to their relative newness, FCW systems differ widely across manufacturers, in terms of what warnings are issued, whether autonomous braking is available, and what objects are detectable.
Four-Wheel Drive (4WD): Useful off-road or when road conditions are very poor, a four-wheel drive vehicle is capable of delivering torque from the engine to all four wheels simultaneously. In contrast, front-wheel and rear-wheel drive vehicles are only capable of delivery engine power to one set of wheels (in a rear-wheel drive vehicle, for example, the rear wheels effectively push the vehicle forward). Four-wheel drive vehicles are able to make more effective use of the available traction on the road.
Human Factors - Hydroplaning
Human Factors: In the context of road safety, human factors refer to behaviours, perceptions, or attitudes of drivers and other road users that have an influence downstream with respect to overall road security. Human factors like the willingness to drive distracted, the proclivity towards aggressive driving, or the sensation-seeking desire to speed can hinder the overall positive effect of advancements in vehicle safety.
Hydroplaning: In order to maintain traction on wet roads, the vehicle’s tires push any standing water away in order to achieve contact with the pavement. If the vehicle is travelling to fast, the water cannot be pushed away and the vehicle ends up sliding on the surface of the water. This sliding is called hydroplaning. Drivers have no steering control over a hydroplaning vehicle, as the tires are not coming into contact with the road directly.
Ignition Interlock: An ignition interlock is a technological tool used to prevent impaired driving. These devices may be installed in the vehicle of a driver who has received an alcohol-related driving citation in order to prevent re-offender. An ignition-interlocked vehicle will not start until the driver has given a breathe sample by blowing into the device. If the interlock device detects evidence that the driver has consumed an unsafe amount of alcohol, the interlock device prevents the vehicle from starting.
Impaired driving: Impaired driving refers to being in control of a motorized vehicle (including motorcycles, passengers cars, boats, and off-road vehicles) while under the influence of alcohol or other drugs. Symptoms of impairment include reduced ability to react and make decisions; reduced ability to control the vehicle; and increased reaction times. With respect to alcohol, drivers may feel the impaired effects of drinking before they reach the federal blood alcohol concentration (BAC) of 0.08%. Crash risk increases dramatically when drivers are impaired.
Lane Departure Warning (LDW) Systems: Introduced for purchase in the mid-2000s, the purpose of lane departure warning systems is to monitor the vehicle’s positioning within the lane and to warn the driver if the vehicle departs the lane unintentionally (i.e., without signalled a lane change). Some of these systems come with a feature that will gently bring the vehicle back into its lane if the driver does not respond to the audible, visual, or haptic warning alarm.
Laser: A laser – or Light Amplification by Stimulated Emission of Radiation – is a device that emits an intense beam of light. Lasers are used for a wide variety of purposes, but in the context of road safety, lasers are sometimes used in features like forward collision warning systems. In this case, a laser is mounted in the vehicle. When the light beam reaches another vehicle, the location, distance, and speed of travel of that vehicle are calculated by the safety system.
Life-Space: The life-space of a vehicle refers to a protected area within the vehicle wherein vehicle occupants have an elevated chance of riding out a crash with relatively minor injuries. Generally, the life-space refers to the area immediately surrounding the seat. To ensure that the life-space is as safe as possible, passive safety features such as seatbelts, airbags, and whiplash prevention systems are often installed.
Passive safety features: Passive safety features are designed to keep vehicle occupants safe within the life-space of the vehicle once a crash has already occurred. Examples of passive safety features include seatbelts, airbags, and whiplash prevention systems.
Pumping the brakes: Pumping the brakes is a technique meant to prevent wheel lock that was taught to drivers prior to the advent of anti-lock braking systems (ABS). By applying and releasing the brakes in rapid succession, drivers may be able to stop their wheels from locking, thereby retaining steering control over the vehicle during an episode of heavy braking. Drivers who have ABS on their vehicles should not pump the brakes.
Radar: In the context of road safety, radar is a system for detecting the presence, direction, and speed of travel of other vehicles. A radar system will emit radio waves, wait for those waves to hit something and bounce back, and will then determine the location, direction, speed of travel of the object based on the radar echo.
Seat belts: First introduced in the early 1900s, seat belts are safety harnesses designed to keep vehicle occupants in their seat during a crash. While they are the oldest safety feature, seat belts are still the single most effective preventative measure against serious or fatal injury in the event of a crash. Seat belts help prevent occupants from being ejected out of the vehicle, or hitting the hard vehicle interior.
Torque: Torque is a force that tends to rotate or turn things. For example, people apply torque when turning a wrench to tighten or loosen a nut: force is applied to the wrench, which in turn creates torque on the nut, and tends to turn the nut. In the context of vehicle power, torque is created by the rotation of the crankshaft.
Traction: Traction refers to the friction that exists between a vehicle’s tires and the road surface. The amount of usable traction available changes depending on a variety of factors, including the weight of the vehicle, the surface of the road, and the condition of the tires.
Traction control: Traction control helps prevent wheels from slipping when accelerating in low-friction conditions. When the traction control system senses that one or more wheels is losing traction, it applies and releases the brakes to the problematic wheel(s) is rapid succession, thereby giving the tires a chance to grip the road.
Tread: The tread of a tire refers to the pattern on the outside of the tire that makes contact with the road. The familiar grooves on the tread allow water to move under the tires, which prevents hydroplaning. Tire tread also improves the vehicle’s ability to maintain traction on the road surface. Tires that have had their tread worn down are sometimes referred to as “bare”, and should be retreaded or replaced.
Unintended Acceleration (UA)
Unintended Acceleration (UA): Unintended acceleration (UA) is defined by the National Highway Traffic Safety Administration in the United States as “the occurrence of any degree of acceleration that the driver did not purposely cause to occur”. UA can be the result of the driver’s foot getting caught around the pedals, objects on the floor causing the accelerator pedal to be pushed down, or, rarely, an electronic malfunction in the vehicle. Brake override is a safety feature that is designed specifically to deal with UA.
Vulnerable Road Users: Vulnerable road users typically refer to pedestrians, cyclists, and motorcyclists. They are called “vulnerable” due to their relative lack of protection when compared to those in vehicles.
Wheel Lock: Wheel lock (or brake lock) occurs when a driver applies the brakes so hard that the wheels stop spinning. The vehicle will usually skid, and the driver may hear an accompanying screeching sound. Of concern, when wheels stop rotating, the driver no longer has steering control over the vehicle.
Wheel Slip: Wheel slip describes what happens when tires lose traction on a low-friction surface. Wheels that have slipped will just spin on the road surface, and drivers will have no control over the vehicle until the wheels regain traction. Wheel slip occurs when the total amount of torque produced by the engine exceeds the total amount of traction available on the road. The less traction available on the road, the lower the wheel slip threshold. This is why it is important to slow down in inclement weather or when road conditions are poor.
Whiplash: Whiplash is a relatively common injury to the bone structures and soft tissues around the neck that typically results from being unexpectedly hit from behind. During a rear-impact collision, the neck and upper spine of the driver who is hit are driven into an unnatural position. Symptoms of whiplash can be temporary or, in more severe cases, chronic, and include neck stiffness, jaw pain, headaches, and ringing in the ears.
Whiplash Prevention: Whiplash prevention systems are designed to prevent the neck and spine from being forced into an unnatural and painful position when a driver is hit from the rear. These systems usually comprise of active headrests that extend upwards in order to cradle the head, and seatbacks that recline slightly during a crash to absorb the force of the body. Cushioning the head and the torso before the contorting forces of a rear-end crash influence their position can help to reduce the instances and severity of whiplash.
Yaw: In the context of road safety, yaw refers to movement - such as twisting or rotation - that occurs around a vehicle’s vertical axis. The vertical axis is an imaginary line that goes from the ground through the center of the vehicle and up towards the sky. Movement occurs around this axis when, for example, the back end of a vehicle swings out due to loss of traction. A more extreme example of a yaw occurs when a vehicle spins out completely.