• LDW systems use video technology to alert a driver if the vehicle is “wandering” into other lanes of traffic or leaving the roadway.
• LDW systems may automatically deactivate if visibility is reduced by snow, fog, heavy rain, bright sun, or other conditions, and may not activate at all if a lane is not clearly marked.

Lane departure warning (LDW) systems use video technology to alert the driver if the vehicle is departing its lane without the turn signal activated. The systems are designed to help the driver avoid “wandering” into other traffic lanes or leaving the roadway. The systems require the installation and calibration of the sensor system, the processor, and the display; and may also require recalibration over time. While this is a data-intensive system, it is normally self-contained and requires only electrical power from the vehicle.

There is an exception in the safety regulation that allows components related to safety systems, such as LDW systems and collision warning systems (CWS), to be mounted on the windshield in locations that are normally not allowed. In 393.60, it states that components for safety systems can be located within four inches of the top of the area of the windshield swept by the wipers and within seven inches of the bottom of the windshield area swept by the wipers, provided they do not obstruct the driver’s view of the road or street signs and signals.

If a vehicle is equipped with a LDW system, the driver may hear an alarm, feel a seat vibration, or see a warning if encroaching on the right or left edge of the lane. These systems rely on cameras and may be automatically disabled if visibility is diminished by snow, fog, heavy rain, bright sun, or other conditions, and may not activate if a lane is not clearly marked. If the system is frequently activating, the driver should find a safe place to park and get some rest.