Similar to forward-collision avoidance, a lane-departure warning system monitors lane markings on the road. It then alerts drivers about unintentional lane drift. Some vehicles warn drivers of lane drift through a steering wheel or seat vibration. Other vehicles use audible or visual warnings.
"The caveat is many of these alarms depend on the driver to react, and multiple alarms might be confusing and difficult to respond to," Lachnit says.
Buick, Mercedes and Volvo have lane-departure warning systems, but the real promise comes with lane-departure prevention. They actively resist moving out of the lane by automatically using slight braking and steering adjustments.
When combined with other technologies, lane-departure warning technology could help prevent crashes. The Insurance Institute of Highway Safety predicts that if all passenger vehicles were equipped with forward-collision warning, lane-departure warning, blind-spot detection and adaptive headlights, about 1 in 3 fatal crashes and 1 in 5 injury crashes could potentially be prevented or mitigated.