Self-Driving Cars and Advanced Driver Assistance Systems (ADAS)

With the emergence of self-driving cars and advanced driver assistance systems (ADAS), the National Highway Traffic Safety Administration (NHTSA), the Center for Child Injury Prevention Studies (CChIPS), the AAA Foundation for Traffic Safety, and others are funding research to study their potential to reduce the number of motor vehicle crashes and save thousands of lives each year.

Research currently being conducted at CHOP and other organizations is looking into the human factors at play when teens use self-driving cars and ADAS. By fully understanding how young drivers interact with and use self-driving cars and ADAS, recommendations can be shared with families to ensure safety during the learning-to-drive process and beyond.

Crash avoidance features and teen-specific vehicle technologies have the potential to prevent or mitigate up to three-quarters of fatal crashes involving teen drivers, according to an Insurance Institute for Highway Safety (IIHS) study. 

To estimate the maximum potential benefits of these technologies, the researchers analyzed passenger-vehicle crashes involving teen drivers that occurred on U.S. roads during 2016-19. They looked for crash scenarios relevant to three crash avoidance features (front crash prevention, lane departure warning/prevention and blind spot monitoring) and three technologies designed for teen drivers (speeding prevention features, nighttime curfew notifications and extended reminders or gearshift interlocks to encourage seat belt use).

Assuming those technologies were universally used and completely effective, the researchers concluded that together they could prevent or mitigate 41% of all crashes involving teen drivers and as many as 47% of teen driver injuries and 78% of teen driver fatalities.

If you are not sure about how self-driving cars and ADAS work and how they have the potential to enhance driver safety, you are not alone. Here’s an overview of what’s available now and what’s on the horizon:

Advanced Driver Assistance Systems (ADAS)

  • Electronic Stability Control (ESC) systems help drivers maintain or regain control of vehicles in difficult driving situations, such as during unexpected turns or while negotiating icy roads. A vehicle’s ESC continuously monitors tire movement and steering wheel activity to sense a loss of traction or slippage. In such situations, ESC systems can reduce engine power, apply brakes independently to each wheel, and correct tire suspension much faster than the driver could. These systems are particularly helpful in managing unexpected events, or driving on wet or icy roadways. They are also especially helpful to drivers of large vehicles, such as SUVs.
  • Adaptive headlights adjust direction and intensity in response to steering to provide additional light on curves, turns and hills or to highlight potential hazards.
  • Rearview video system (RVS), also known as a backup camera, allows drivers to view the area behind the rear bumper and see small objects that may be obstructed by the vehicle’s blind spots or may not ordinarily be visible at all. There are several versions of RVS: Some simply provide a view from the back of the vehicle, while others pair this view with a sensor that warns (audible alarm) if an object is detected too close to the back of the vehicle and may even apply the brakes automatically to prevent a potential collision.
  • Adaptive (Automatic) Cruise Control (ACC) senses where the vehicle in front is relative to the driver’s own vehicle and slows down and speeds up to maintain consistent spacing. Unlike traditional cruise control, which can only be set to a single speed, ACC can adapt when other vehicles change their speed.
  • Lane Departure Warning (LDW) systems alert drivers whenever they unintentionally drift too close to the edges of the lane. The warning type varies between car manufacturers; some use an alarm sound, while others cause the driver’s steering wheel or seat to vibrate, creating a feeling like driving over a rumble strip. LDW systems should not be confused with Lane Departure Prevention systems (described below).
  • Lane Departure Prevention (LDP) systems, also known as lane keeping assistance, help keep a vehicle from unintentionally drifting from its lane. LDP uses a camera to monitor the distance between the vehicle and lane markings. If the vehicle drifts towards the lane markers, the system first sounds an audible warning, followed by a selective application of the brakes to help move the vehicle back into its lane.
  • Forward Collision Mitigation (FCM) systems detect how far and fast the vehicle in front may be moving and automatically apply the brakes if the driver does not respond. In this way, FCM systems work to reduce the chance of crashes and reduce the severity of crashes when they occur. FCM should not be confused with Forward Collision Warning systems (described below).
  • Forward Collision Warning (FCW) systems alert the driver when the vehicle is about to collide with another vehicle some distance ahead. The type of warning will vary between vehicles: Some use a flashing light, while others use an alarm sound or vibration.
  • Automatic emergency braking (AEB) systems detect an impending forward crash with another vehicle in time to avoid or mitigate the crash. These systems first alert the driver to take corrective action to avoid the crash. If the driver’s response is not sufficient to avoid the crash, AEB may automatically apply the brakes to assist in preventing or reducing the severity of a crash. There are two types of AEB currently available: dynamic brake support (DBS) and crash imminent braking (CIB).  If the driver brakes but not hard enough to avoid the crash, DBS automatically supplements the driver’s braking in an effort to avoid the crash. If the driver does not take any action to avoid the crash, CIB automatically applies the vehicle’s brakes to slow or stop the car, avoiding the crash or reducing its severity. Research conducted at CHOP published in Safety Science show that AEB prevented 57% of rear-end striking crashes involving 16- to 19-year-old drivers and 81% involving 20- to-24-year-old drivers. 
  • Pedestrian Automatic Emergency Braking (PAEB) systems are an emerging technology and provide automatic braking when pedestrians are in front of a vehicle and the driver has not acted to avoid a crash. PAEB systems have been found to be effective in reducing crashes involving pedestrians. However, according to a 2022 Insurance Institute for Highway Safety (IIHS) study, they do reduce the rate of pedestrian crashes with injury by 30% during daylight but do not appear to reduce the rate of crashes in darkened conditions.
  • Automatic Crash Notification (ACN) systems notify emergency responders that a crash has occurred and provide its location. When the ACN sensor detects air bag deployment or a dramatic and sudden drop in speed, an automatic connection is made with an operator. An emerging technology, ACN systems have the potential to reduce the rate of death and disability by decreasing the time it takes for emergency medical services to arrive at a crash scene and transport those involved to a hospital.

To learn more about how these ADAS technologies work, watch these videos from NHTSA featuring’s Adam Savage.

Self-Driving Cars

As ADAS technologies improve, they may eventually result in vehicles that can control all aspects of the driving task: truly “self-driving” cars. Also known as “autonomous vehicles,” self-driving cars are in development, but none are yet available to the consumer. Self-driving cars come in various levels and include those with:

  • Limited Self-Driving Automation, where the driver surrenders complete operation of the primary functions under certain traffic and environmental conditions. It's up to the vehicle to monitor its surroundings and make the decision to transfer operation back to the driver. According to NHTSA, such a transfer would occur when the vehicle realizes it's coming upon a construction zone and alerts the driver to reassume control.
  • Full Self-Driving Automation, where the vehicle is responsible for the safe operation of all critical functions for an entire trip. Here, the driver's sole responsibility would be to provide the destination; it's the vehicle's job to safely reach it.

NHTSA is committed to advancing this technology to eliminate crashes in self-driving cars, but safety concerns remain regarding the transfer of control back and forth between driver and vehicle. Researchers at CHOP and others are studying these issues to help inform the development of self-driving cars and recommendations for how to use them safely.