Chapter 15: Driver assistance systems (ADAS)

1. What are ADAS?

Advanced Driver Assistance Systems (ADAS) are technologies designed to enhance vehicle safety and driving comfort by assisting the driver in various tasks, warning of potential hazards, and, in some cases, taking partial control of the vehicle to avoid accidents. They do not make the vehicle autonomous: the driver must remain attentive and ready to take control.

2. What are the Main ADAS Features?

Common driver-assistance and related vehicle functions include:

• Hill Start Assist (Hill Holder): Prevents the vehicle from rolling backward on an incline by holding the brakes briefly after the driver releases the brake pedal.
• Intelligent Speed Assistance (ISA): Uses cameras and/or map data to identify speed limits and warn or assist the driver in keeping within them. It can misread limits; the driver must check the signs and remains responsible for speed.
• Electronic Brakeforce Distribution (EBD): Optimizes brake pressure between wheels for maximum stability and stopping power, especially under heavy braking.
• Autonomous Emergency Braking (AEB / AEBS): Detects imminent collisions and applies the brakes automatically if the driver does not react in time.
• Adaptive Cruise Control (ACC): Maintains a set speed and safe following distance from the vehicle ahead by automatically adjusting throttle and brakes.
• Traffic Jam Assist (TJA): Builds on ACC and LKA to provide hands-on semi-automated driving in slow-moving traffic, controlling speed, distance, and steering within the lane.
• Lane Keeping Assist (LKA): Monitors road lane markings and gently steers or warns the driver if the vehicle drifts out of its lane without signaling.
• Lane Centering / Emergency Lane Keeping: Lane centering helps maintain a central lane position. Emergency lane keeping (ELKS) intervenes during a dangerous unintended lane departure; it is a different function, not a general obstacle-avoidance system.
• Blind Spot Detection (BSD / BLIS): Alerts the driver to vehicles in adjacent lanes that may not be visible in the mirrors.
• Rear Cross Traffic Alert (RCTA): Warns of approaching traffic from the sides when reversing out of parking spaces.
• Traffic Sign Recognition (TSR): Uses a forward-facing camera to detect and display road signs (e.g., speed limits, no-entry) on the instrument cluster.
• Forward Collision Warning (FCW): Provides visual and/or audible alerts when a frontal impact is likely unless corrective action is taken.
• Rear-view Camera & Parking Sensors: Offer visual and/or audible assistance for low-speed maneuvers and parking.
• High Beam Assist (Automatic Headlight Control): Switches between high and low beams depending on oncoming or preceding traffic.
• Automatic Headlight & Wiper Activation: Turns on headlights or windshield wipers when sensors detect low light or rain.
• Driver Monitoring & Drowsiness Detection: Driver drowsiness and attention warning (DDAW) detects signs of reduced alertness. Advanced driver distraction warning (ADDW) is a separate function that warns when attention is diverted from driving.
• Pedestrian & Cyclist Detection: Identifies vulnerable road users and can warn or automatically brake to prevent a collision.
• Intersection Assist: Scans cross-traffic at junctions and can alert the driver or brake if another vehicle is about to collide.
• eCall / Emergency Call: Automatically contacts emergency services in a serious crash, transmitting the vehicle’s location.
• Start-Stop System: A fuel-saving function that shuts off the engine at idle (e.g., at traffic lights) and restarts it when the driver is ready to move; it is not a collision-prevention ADAS.
• Semi-Autonomous “Pilot” Modes: Integrates multiple ADAS features (ACC, LKA, TJA) to enable hands-on semi-automated driving under certain conditions.

Depending on the function, these systems use cameras, radar, ultrasonic sensors, maps and other inputs. Rain, fog, dirt, damaged sensors or unclear markings can limit them. Keep sensors clear and follow the manufacturer’s instructions, including calibration after relevant repairs.

For newly registered cars and vans in the EU, requirements from 7 July 2024 include ISA, DDAW, reversing detection, emergency lane keeping and automatic emergency braking, among others. From 7 July 2026, advanced distraction warning (ADDW) and emergency braking that also detects pedestrians and cyclists are required. These dates do not impose a general retrofit on older vehicles. ACC and a separate traffic-sign-recognition display are not universally mandatory.