Advanced driver assistance Skip to content Vehicle ratings News Research areas About Home Research areas Advanced driver assistance Home Research areas Advanced driver assistance Advanced driver assistance Overview Front crash prevention Lane departure warning and lane departure prevention Blind spot detection Rear crash prevention Limitations of crash avoidance technologies Automation Safety issues raised by partial driving automation Deployment of highly automated vehicles V2V and V2I Overview The information on this page was compiled by Alexandra Mueller, a senior research scientist at IIHS. Alex studies driver assistance technologies and driving automation. Her research formed the basis of IIHS partial automation safeguard ratings. Contact Alex. Truly driverless cars aren’t for sale yet. More vehicles are incorporating a degree of automation with technologies such as adaptive cruise control and lane centering, but the driver will continue to share driving responsibilities for the foreseeable future. In theory, fully automated driving could eliminate the vast majority of crashes, but that level of automation won’t be parked in your driveway anytime soon. Advanced crash avoidance features are becoming widespread. Many of today’s vehicles have technologies that monitor driver input and the environment around the vehicle and warn the driver when they detect the possibility of a crash. They may automatically brake or steer the vehicle if the driver does not act to avoid the collision. Some driver assistance technologies are reducing crashes. Front crash prevention, lane departure prevention, blind spot detection and rear crash prevention also show real-world crash reductions. Real-world benefits of crash avoidance technologies Summary of IIHS-HLDI findings Latest news Latest news The real reasons repair costs are so high The sensors used for automatic emergency braking, blind spot detection and other crash avoidance systems are often blamed for high repair costs, but there are many other causes. Matt Moore, Chief Insurance Operations Officer, IIHS-HLDI August 11, 2026 How safe are driverless cars? Waymo’s driverless vehicles have crash rates that are 68% lower than human drivers, new IIHS research shows. But as the technology is deployed more widely, a better system for tracking safety is needed. July 23, 2026 Front crash prevention Front crash prevention systems are designed to intervene when the vehicle is about to rear-end another vehicle. The technology uses various types of sensors, such as cameras, radar or lidar — short for light detection and ranging — to detect when the vehicle is getting too close to one in front of it. The systems generally issue a warning and precharge the brakes to maximize their effect. Most also apply the brakes if the driver doesn’t respond. Many front crash prevention systems can detect pedestrians, and some also recognize cyclists and animals. These systems use advanced algorithms coupled with sensors and cameras to spot nonmotorists who are in or about to enter the vehicle’s path. Front crash prevention is becoming more universal and its capabilities more consistent across brands, thanks to a voluntary commitment by 20 automakers, representing 99% of U.S. light vehicle sales, to make the technology standard by September 2022. The commitment, brokered by IIHS and the National Highway Traffic Safety Administration (NHTSA), called for vehicles to have systems with both a forward collision warning component that met NHTSA criteria and automatic braking that achieved certain minimum speed reductions in IIHS track tests. In 2024, NHTSA finalized a requirement for front crash prevention on nearly all new vehicles with a gross vehicle weight rating of 10,000 pounds or less by September 2029 (NHTSA, 2024). Under the rule, systems must be operable in both daylight and dark conditions. They must provide a warning and automatically brake in response to a vehicle ahead at speeds up to 90 mph and in response to a pedestrian at speeds up to 45 mph. Vehicles equipped with front crash prevention are much less likely to rear-end other vehicles than the same models without the technology (Cicchino, 2017; Fildes et al., 2015; Isaksson-Hellman & Lindman, 2016; Partnership for Analytics Research in Traffic Safety, 2025). An Institute study found that systems with forward collision warning and automatic braking cut rear-end crashes in half, while forward collision warning alone reduces them by 27% (Cicchino, 2017). The autobrake systems also greatly reduce rear-end crashes involving injury. A separate IIHS study showed that automatic braking systems that recognize pedestrians cut pedestrian crashes by 27% (Cicchino, 2022). Passenger vehicles are not the only vehicles that benefit from front crash prevention systems. Similar rear-end crash reduction effects have been found for large trucks equipped with front crash prevention systems (Teoh, 2021). HLDI has conducted studies comparing insurance claim rates for passenger vehicles equipped with front crash prevention with claim rates for the same models without the technology. Vehicles equipped with these systems consistently show lower rates of claims for damage to other vehicles and for injuries to people in other vehicles (HLDI, 2023). Similarly, HLDI found that Subaru’s EyeSight system with pedestrian detection cut the rate of likely pedestrian-related insurance claims by 35%, compared with the same vehicles without the system (Wakeman et al., 2019). Even if a front crash prevention system doesn’t avoid a crash altogether, it may still reduce the impact speed, thereby making a crash less severe. To show why reducing speed is important, IIHS conducted two demonstration crash tests at different speeds in 2013. In each test, a 2013 Mercedes-Benz C-Class ran into the back of a stationary 2012 Chevrolet Malibu. The tests illustrated what happens in a 25 mph crash when the striking vehicle doesn’t have autobrake, compared with what happens when the speed is reduced by 13 mph, the amount by which the C-Class's autobrake system reduced the impact speed in IIHS track testing. Damage in the higher speed crash test was about $28,000. The Malibu was a complete loss. Lowering the speed to 12 mph trimmed the damage to $5,700 (IIHS, 2013). A similar speed reduction in a higher-speed crash could significantly reduce injury risk as well as vehicle damage (Kraft et al., 2009). Front crash prevention systems with automatic braking have resulted in bigger reductions in rear-end crashes with injuries than in rear-end crashes of all severities, which suggests that these systems are preventing injuries in some rear-end crashes that aren’t avoided (Cicchino, 2017). IIHS has rated front crash prevention systems since 2013 and began rating pedestrian detection systems in 2019. Lane departure warning and lane departure prevention These systems use cameras to track the vehicle’s position within the lane, alerting the driver if the vehicle is in danger of inadvertently straying across lane markings when the turn signal is not activated. Some lane departure warning systems use haptic feedback, such as steering wheel or seat vibration, while others use audible and/or visual alerts. Lane departure prevention systems cause the vehicle to actively resist moving out of the lane or help direct the vehicle back into the lane through light braking or minor steering adjustments. Lane departure warning has not brought down insurance claim rates (HLDI, 2023) but has reduced rates of single-vehicle, sideswipe and head-on crashes reported to the police (Cicchino, 2018; Partnership for Analytics Research in Traffic Safety, 2025; Sternlund et al., 2017). Blind spot detection This feature uses sensors to monitor the side of the vehicle for vehicles approaching blind spots. In many systems, a visual alert appears on or near the side mirrors if a vehicle is detected. An audible alert may activate if the driver signals a turn and there is a vehicle in the blind spot. Some systems also may activate the brake or steering controls to keep the vehicle in its lane. Blind spot detection has been shown to reduce lane-change crashes by 14% (Cicchino, 2018). HLDI research has also found that blind spot detection lowers rates of insurance claims covering injuries and damage to other vehicles (HLDI, 2023). Rear crash prevention There are many different technologies designed to help drivers back up safely. Rearview cameras display what is behind the vehicle, projecting a much larger field than is visible in mirrors or even by looking directly out the back windshield. Since May 2018, rearview cameras have been essentially required on new vehicles in order to reduce backover crashes, in which young children are frequently the victims (Office of the Federal Register, 2014). Some camera systems, as well as systems that use radar or ultrasonic sensors, warn the driver if there are objects in the way when the vehicle is in reverse. Systems with rear automatic braking apply the brakes to keep the vehicle from backing into or over an object. A rear cross-traffic alert system detects vehicles approaching from either side that may cross the path of a backing vehicle, warns the driver, and may automatically brake to prevent a collision. Rear automatic braking is associated with the largest reductions in insurance claims and backing crashes reported to the police of any type of rear crash prevention system (Cicchino, 2019; HLDI, 2023). IIHS has issued ratings for some rear crash prevention systems. Limitations of crash avoidance technologies Crash avoidance technologies can’t be effective unless they are used. Appropriate driver responses and acceptance of these technologies are critical to their success. If drivers don’t trust the systems or find them annoying or not useful, they may disable them. Similarly, if drivers experience warnings but don’t understand them, are overwhelmed by them, or don’t take an appropriate corrective action, then the systems will be ineffective. Observations of over 2,000 vehicles that arrived at dealerships of six automakers in 2023 found that automatic emergency braking systems were activated in 93% (Cox et al., 2025). Among vehicles in the study that were equipped with lane departure warning but not lane departure prevention, 57% had the warning system active. Most vehicles were equipped with both lane departure warning and prevention. Of those, 87% had either the warning only (11%) or both warning and prevention (76%) activated. A similar study conducted in 2016 found lane departure systems that warned by vibration were more likely to be activated than those that beeped, and almost all vehicles equipped with blind spot detection and rear-cross traffic alert systems had those systems switched on (Reagan et al., 2018). Drivers need to be ready and able to respond to a vehicle's warnings or interventions in order for these crash avoidance technologies to work. Many drivers involved in lane departure crashes are asleep or otherwise incapacitated, making it hard to respond (Cicchino & Zuby, 2017; Wiacek et al., 2017). Systems that only warn the driver are not as effective as those that act on behalf of the driver, such as automatic braking (Cicchino, 2017). However, even systems that intervene will likely require a follow-up response from the driver. In addition to driver challenges, the technology itself can have limitations. For example, lane departure warning and prevention systems use sensors to register lane markings or the road edge, which may be problematic on roads that aren’t well-marked or are covered with snow. Sensors may not function well in low light or inclement weather. Some systems only work at certain speeds. While pedestrian crash avoidance systems are effective during the day or on lighted roads, they can struggle to detect pedestrians in the dark (Cicchino, 2022). However, systems o…