Lane departure warning (LDW)

Lane departure warning (LDW) is an advanced driver-assistance system that warns the driver when the car is drifting out of its lane.

How does it work? LDW uses a camera to detect the lane lines on the road. The camera is usually mounted in the windshield near the rearview mirror. When the car drifts near or on the line, the system gives a warning. The warning is usually a beeping sound and/or a visual flashing indicator on the dashboard or head-up display. Some systems also vibrate the steering wheel or seat cushion. The system is not activated when the driver uses the turn signal.

The purpose of lane departure warning is to lower the possibility of an accident resulting from distractions and sleepiness. The warning draws the driver’s attention to the road and they can pull the car back to the lane. LDW does not take any actions – it only gives a warning and the driver has to act. The system is limited to roads with good lane markings. When the marks have faded, LDW might have trouble recognising them. Extreme weather conditions such as heavy snow, rain or fog can also make it hard to detect the lines.

LDW is the most basic system of lane support safety tech. The next step is lane keeping which gently steers the car back if the driver does not react to the warning. The most advanced lane support system is lane centring. It is a proactive system that automatically keeps the car in the centre of the lane, steering it gently. The driver still has to hold their hands on the wheel. But they can drive smoothly through light corners without turning the wheel themselves.