What is active safety in a vehicle?

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08 Oct 2019 by smartleasing

Active safety features are common now on many cars, and even vehicles under $20,000 can come with more than one type of active safety feature. But what is active safety?

Unlike passive safety, which are mechanisms to reduce injury of occupants once a crash has already occurred, active safety systems can reduce the severity of a crash or prevent it altogether. They do this by constantly monitoring the car and what is happening around the car using special cameras and sensors. Some of the data calculated every second by active safety systems can include monitoring the movement of other traffic and their speed and looking for pedestrians and cyclists. That data is then matched with what the car is doing, such as what speed it is at, if the driver is pressing the brake pedal, if it’s raining or wet, and do the tyres have sufficient traction or not.

It’s all very complicated, but the purpose of active safety systems is easy to understand. Here are some of the most common active safety systems and how they can help prevent an accident.

Automatic emergency braking (AEB)

AEB is a requirement to achieve a maximum five-star ANCAP safety rating in Australia, so you’ll see this technology on many new vehicles. It alerts the driver if there is stopped or slowed traffic ahead that the car will come into contact with, and if the driver does not respond, it will begin to apply the brakes automatically. The system can also help the driver to ensure maximum braking force is applied. Beyond scanning for vehicles, some systems are further equipped with pedestrian and cyclist detection.

Forward collision warning (FCW)

FCW scans for traffic ahead and will warn the driver (usually with audible and visual, and sometimes haptic alert) to brake if the speed of the car is likely to crash into traffic ahead. However, unlike AEB, it will not apply the brake – a key difference between the two technologies.

Active cruise control (ACC)

An extension of AEB and using most of the same radar and cameras, active or adaptive cruise control as it is commonly known, is cruise control that automatically brakes and accelerates as the vehicle follows other traffic. Let's say you set the ACC at 100km/h and began to approach traffic at 80km/h, the vehicle will automatically slow down and keep a safe distance from it. Once the traffic speeds back up to 100km/h again, the car will automatically do the same, all while keeping a consistent gap between it and the car ahead, though it will not go faster than the speed set by the driver.

Lane departure warning (LDW)

Another technology that ANCAP requires to give a car a full five-star rating is LDW. This uses cameras to read line markings on the road and warn the driver if the vehicle begins to leave the lane. Some of the more sophisticated systems, usually found on higher model grade cars, have technology that can further read markings such as kerbs and gutters where there are no lane guides. LDW is an important safety system to help prevent cars from driving into oncoming traffic.

Lane-keeping assist (LKA)

While LDW (above) warns the driver if the vehicle is leaving its lane, LKA goes one step further by actively steering the car. An audible, visual, and sometimes haptic alert is given while the car begins to steer back into its lane. It does this by using motors that can turn the steering wheel, and some of the leading systems available right now can steer the car without hand input for up to 40 seconds before warning the driver to hold the steering wheel. This technology is part of the segue into autonomous driving.

Blind-spot monitoring

As advertised on the box, this system uses sensors to detect cars that are in the driver’s blind-spot and alert them that a car is there. Usually this is done by a warning light in the side mirror or on the dash which glows as traffic approaches. Some systems further alert the driver if they begin to merge into traffic in the blind spot.

Rear cross-traffic alert (RCTA)

An extension in some ways of blind-spot monitoring, RCTA is useful when backing out of car parks with reduced rearward vision. The system will alert the driver if they are reversing into crossing traffic, and some more sophisticated cars will further aid by applying the brake so a collision is avoided.


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