Everything You Need to Know About Car Safety TechAndi Hedrick - Car and DriverIt seems new driver-assistance safety features enter the market about as often as new additions to the Taco Bell menu. Due to this, it's easy to be confused about which technologies do what and which acronym corresponds to which function. Understanding how these features operate and how they can help you avoid an accident is key to deciding if option packages that include them are worth the extra coin.If you purchase a vehicle that has some or all of these features, it's important to know how they work and why sometimes they don't–and what to do if one should alert you to an impending incident. To help, we've listed the lion's share of current driver-assistance features, along with an explanation of how each functions, below.Adaptive Cruise Control (ACC)Adaptive cruise control is a convenience feature that uses the car's radar and/or camera modules to alter the set cruising speed if it detects a slower vehicle ahead. When adaptive cruise control is engaged, the car will maintain a specific distance from the car in front; many cars come with three set options for the following distance. Some advanced versions of the feature will also bring the vehicle to a complete stop if the car ahead stops and will then start to back up when traffic begins to move. Such a feature is quite handy and reduces driver fatigue by allowing the use of cruise control in dense-traffic driving scenarios.Jeff Xu - Car and DriverActive Park Assist (APA)Vehicles equipped with active park assist use sonar and radar to seek out and measure empty parking spots, and then actively steer the vehicle into them. Some of these systems require the driver to operate the accelerator and brake. Some manufacturers offer both parallel- and perpendicular-parking capability, but some limit the vehicle to one or the other. In our experience, these systems aren't perfect and are occasionally tripped up by curbs, closely parked vehicles, or other environmental factors.Jeff Xu - Car and DriverAutomated Emergency Braking (AEB)Using forward-facing cameras and/or radar, vehicles with automated emergency braking will warn the driver of an imminent forward collision with another vehicle, pedestrian, or object and then brake the vehicle on behalf of the driver if no action is taken. Some vehicles also come with a similar automated emergency braking system that works when reversing. We tested automated emergency braking on several vehicles. We found that while they do indeed work as intended, they don't always brake hard enough or early enough to avoid the collision altogether, so drivers should not rely entirely on such features. Some systems work only at low speeds, while more advanced systems work even at highway speeds.Jeff Xu - Car and DriverAutomatic High-Beams (AHB)Headlamp systems that automatically switch to high-beams might seem like a new feature, but this tech has actually been around since the 1950s, when it debuted on General Motors' Cadillac, Buick, and Oldsmobile cars. Unlike those early systems, which relied on light-sensitive sensors that proved to be somewhat unreliable, today's automatic high-beams are controlled by high-tech camera modules that can more easily discern between an oncoming vehicle's headlamps and the reflection from road signs.Jeff Xu - Car and DriverAdvertisementAdvertisementBlind-Spot Monitor (BSM)Using sonar sensors in the rear bumpers, or sometimes cameras in the exterior mirrors, blind-spot monitoring systems watch adjacent lanes and can alert the driver to other vehicles that might be in the driver's blind spots. Most cars with this feature have warning lights in or near the exterior mirrors that illuminate or flash when a vehicle is detected close by and one lane over; some vehicles also beep if the turn signal is activated while a car is in the adjacent lane. We find blind-spot monitors generally work quite well and can help keep you from cutting off another driver or worse.Jeff Xu - Car and DriverDriver-Attention Warning (DAW)This type of system keeps an eye on the driver to help prevent accidents caused by drowsy and distracted driving. Most systems use sensors to monitor the car's movements and the volume of steering corrections to determine if the driver is attentively driving or is tired or texting. Others use interior-mounted cameras to make sure the driver's eyes are focused on the road ahead. These systems provide a visual or audible alert to encourage taking a break from driving to perk up.Jeff Xu - Car and DriverForward-Collision Warning (FCW)Similar to adaptive cruise control, forward-collision warning systems use radar and/or cameras to watch the road ahead for slow or stopped traffic. Forward-collision warning is a more basic form of collision mitigation and will alert the driver–usually with both a visual and an audible warning–if a collision is imminent. The goal is that the alert gets the driver to immediately slam on the brakes. These systems are sometimes accompanied by automated emergency braking that will brake for the driver if no action is taken, but drivers should be aware that not all vehicles include both features.Jeff Xu - Car and DriverLane-Departure Warning (LDW)Lane-departure warning is usually a camera-based driver-assistance feature that looks for lane markings and alerts the driver if the vehicle is in danger of wandering out of its lane or has begun to exit the lane without the turn signal being activated.Jeff Xu - Car and DriverAdvertisementAdvertisementLane-Keeping Assist System (LKAS)Unlike a lane-departure warning system, a lane-keeping-assist system will help prevent lane departure by making small corrections to the steering to keep the vehicle in the intended lane. While some systems still provide a visual or an audible alert to accompany the lane departure, some cars with lane-keeping assist will just quietly recenter the vehicle in the lane. This is usually easy to feel from behind the wheel as the car changes direction and the steering wheel moves without any steering adjustment by the driver.Jeff Xu - Car and DriverNight VisionNight-vision features aren't yet a widespread driver-assistance feature. Currently, night-vision systems are offered on a handful of luxury models. These systems rely on forward-facing thermographic cameras to watch for pedestrians, animals, and vehicles not easily seen in the dark by the naked eye. A small display, usually on the vehicle's infotainment screen, shows an image of what's ahead, with potential obstacles outlined in a heat signature. Depending on the system, the driver may receive a separate visual or audible alert to accompany the detection of an obstacle.Jeff Xu - Car and DriverParking SensorsParking sensors–also called proximity sensors–aid the driver during parking maneuvers by using ultrasonic transducers to locate obstacles such as parked cars, tall curbs, or bollards and alert the driver with a series of beeps that increase in tempo as the vehicle nears the object. Sensors are generally located on the front and rear bumpers.Jeff Xu - Car and DriverPedestrian DetectionIn an attempt to protect those outside the vehicle, many modern cars come with a pedestrian-detection system that typically relies on cameras to watch for people crossing the street or riding their bicycles in a shared lane. Some vehicles with this feature will also automatically brake if the system senses a collision with a pedestrian is imminent.Car and DriverAdvertisementAdvertisementRear Cross-Traffic Alert (RCTA)Using the same ultrasonic transducers as the vehicle's parking-sensor system or the sonars used for blind-spot monitoring, rear cross-traffic alert can warn the driver of vehicles or pedestrians approaching the rear of the vehicle from the side. The feature is particularly useful when backing out of parking spots in crowded lots. Some vehicles will also apply the brakes automatically to stop the vehicle if the system senses a collision is possible.Jeff Xu - Car and DriverHands-Free Driving AssistMultiple automakers offer hands-free driving assist systems. While the technology itself falls short of turning your car into anautonomous vehicle, it can take over steering duties from the driver—provided the driver is paying attention to the road and ready to take over control at a moment's notice. The amount of hands-free driving these systems can do varies by manufacturer, with some limiting the function strictly to pre-mapped highways, and others capable of handling city streets.Jeff Xu - Car and DriverTraffic-Sign Recognition (TSR)Traffic-sign recognition systems use the road-facing camera(s) to look for road signs, such as a posted speed limit. It then presents this information to the driver as a reminder. Some systems can also recognize signs that indicate restrictions on passing and other road warnings. The traffic sign is often projected on the car's head-up display, gauge display, or infotainment screen as a reminder to the driver.Jeff Xu - Car and DriverYou Might Also LikeAdvertisementAdvertisementGift Guide: Best Ride-On Electric Cars for KidsFuture Cars Worth Waiting For: 2025–2029