What You Need to Know About Lane Departure Warning

What is Lane Departure Warning?
Lane departure warning is an in-car safety system that alerts you through visual and audible signals if your car unintentionally leaves a marked lane. Some cars even alert you by vibrating the steering wheel or driver’s seat but most sound a chime and/or illuminate a warning light somewhere on the dashboard. The system employs a small forward-facing camera mounted on the inside mirror or two cameras mounted near the outside mirrors. The cameras continuously monitor lane markings to determine if your car leaves a marked lane without intentional driver action or use of a turn signal. Lane departure warning systems can be turned off by the driver although some vehicles reactivate the system automatically each time you start the car.

How does lane departure warning help me and my passengers?
In a 2002 National Sleep Foundation poll, more than half of U.S. drivers reported driving while tired or drowsy and 17 percent say they had actually fallen asleep behind the wheel within the previous year. This is the ideal situation for a lane departure warning system. If a drowsy driver starts to nod off while driving a car with lane departure warning, the buzzer or chime will likely get their attention focused back on the road.  Distracted driving is another problem that leads to traffic accidents and lane departure warning is helpful here too. Because distracted drivers likely don’t know they’re drifting out of their lane and onto the shoulder or into on-coming traffic, an audible, visual or other sensory warning could help prevent a serious accident.

However, there are limitations to the technology. Lane departure warning systems rely on painted or marked lanes. If you frequently travel on roads that do not have marked lanes, the feature may not be for you. Also, lane departure technology works best on highways or major surface streets. If you drive only a few miles to work or do only low-speed in-town driving, lane departure may not be right for you either. Drivers with long commutes on mostly open roads, those who frequently drive late at night or often have small children in the car, and anyone prone to distracted driving will benefit most from a lane departure warning system.

Is lane departure warning a must-have on my car?
Lane departure warning is a great safety feature but it really shouldn’t be seen as a deal breaker when buying a new or used car. The feature was introduced around 2005 so it’s likely some used-car shoppers will come across lane departure warning systems.

It’s important to know that lane departure warning isn’t the same as an attention monitor or a blind-spot detection system.  Cars like the Lexus HS250h actually can monitor where the driver is looking and sound a warning if it seems an accident is about to occur based on inattentiveness.  Similarly, blind-spot detection tells the driver if another vehicle is in their over-the-shoulder blind spot. In contrast to these systems, lane departure warning monitors only whether your car is leaving a marked lane. So while it might help a sleepy driver on a road with marked lanes, lane departure warning isn’t monitoring where the driver is looking or monitoring for nearby vehicles in your blind spot. 

Lane departure warning is primarily found on luxury brand cars such as BMW, Buick, Cadillac, Infiniti, Lexus, Mercedes Benz and Volvo. Some BMWs and other high-end vehicles offer lane departure warning and blind-spot detection as standard equipment, but often only on the more-expensive models in the lineup. Mostly, lane departure is an option and is frequently grouped with blind-spot monitoring and other safety systems into technology or advanced safety packages.

However, lane departure is beginning to show up on some moderately priced cars. It’s available on the Toyota Prius hybrid and is likely to be offered on the redesigned 2012 Toyota Camry due sometime in 2011. But it isn’t inexpensive, partly because it’s current included in those options packages, which typically cost around $3,000 or more. For example, the Toyota Prius has a starting price of around $22,000, but lane departure warning is available only on the highest priced Toyota Prius V model, which starts around $28,000. Lane departure warning is part of a $5,100 Advanced Technology Package that also includes a JBL stereo, backup camera, Bluetooth and roadside assistance. On the 2011 Infiniti M37, lane departure warning is part of a similarly wide-ranging $3,000 technology package. As the public demands more safety features, however, lane departure warning will be offered on more cars, and that will bring its price down.

Ultimately, of course, technology can’t save a careless driver. There’s no substitute for getting a full night’s sleep or for paying full attention to all that’s around you while driving. Still, the reality is many people find themselves in driving situations that sneak up on them, like suddenly getting tired just a few miles from home. That’s when safety systems like lane departure work best. Fortunately, there’s a great side benefit to lane departure warning; the system is defeated when a driver uses the turn signals. If having a lane departure system on our cars forces everyone to signal more often, maybe it’s done its job without ever making a sound.