Modern Safety Features and You: Tech that Keeps You in Your Lane

What you need to know about blind spot monitors and lane departure warning systems.

Nissan's Lane Keep Assist SystemNissan

Article QuickTakes:

From the moment we get our first coloring book, the importance of staying between the lines is programmed into our brains. As we get older and trade crayons for cars, those lines become lanes on the road and, even if we never do fully perfect the art, staying between them becomes an imperative. Knowing when we can safely cross those lines – changing lanes, etc. – is one of the key skills that separates safe drivers from the not-so-safe.

Enter modern safety features and driver aids. Just as some cars can help you stop before a serious collision, up to a third of new vehicles offer some sort of blind spot sensor. Some systems will help you stay in your own lane if your attention wanes, and a few can even do the lane change for you.

These features aren’t often free, however, so understanding exactly what each does and doesn’t do is crucial if you want to make an informed decision when buying your next car.

Aaron Miller

A blind spot monitor can offer reassurance that no one’s next to you… but it isn’t an excuse to not look before changing lanes.


What is it?

A blind spot detection system uses a suite of sensors to detect any vehicles cruising in the hard-to-see space behind and to the side of your car, and alerts you to their presence. It can be combined with a lane change alert system, which provides an audible or tangible warning – in the form of a beep or a vibration – if you put your turn signal on while someone’s in your blind spot.

What are the pros?

The Insurance Institute for Highway Safety conducted a study in 2015 that found blind spot monitors can reduce crashes caused by lane changes by as much as 14%, lending statistical credence to the idea that they really do work.

Aside from the safety advantages, a blind spot warning system is the high-tech answer to the decades-old convex “blind spot mirror,” which can be an unsightly blight on the otherwise clean lines of a modern vehicle.

What are the cons?

While a blind spot monitor offers reassurance that no vehicle is lurking where you can’t see it, it’s not perfect, so you have to be careful not to over-rely on the system. In other words, blind spot monitors are an aid, but do not absolve you from checking that the coast is clear. AAA conducted an extensive blind spot monitor test a few years ago and found that many couldn’t reliably detect fast-approaching vehicles, and they had difficulty detecting motorcycles as quickly as other vehicles.

What should you look for?

Manufacturers use different methods to alert you that a vehicle is in your blind spot. Some have lights built into the side mirrors, while others use lights mounted inside the car. When equipped with a lane change alert, you should find out if the warning is purely audible or if it provides a haptic response (i.e. vibrating the steering wheel, which won’t alarm everyone else in your car).

And keep in mind that not all vehicles offer the same range of vision. In a compact convertible with excellent visibility, a blind spot monitor’s benefits might be minor. But in a large SUV with an equally large blind spot, it could be very noticeable.

How much does it cost?

As with so many other features, blind spot monitors range from standard equipment to an optional add-on. Many blind spot systems also include a rear cross-traffic alert, which uses the same sensors to detect anyone coming from the side when you’re backing up, like kids running down a sidewalk or a neighbor speeding down the alleyway. In a 2018 Ford Mustang, for example, the Blind Spot Information System (BLIS) comes with Cross-Traffic Alert, but only a) with the upgraded “Premium” trim level, and b) as part of a package that also includes other safety and convenience features like Automatic Emergency Braking, Forward Collision Warning, memory driver seat settings and ambient lighting. The package itself costs MSRP $1,495*, though the trim upgrade runs $5,015*. On a 2018 Honda Civic, meanwhile, it’s available on the base LX trim as part of the MSRP $1,000* Honda Sensing suite of driver aids, but only if you select the continuously variable transmission instead of a 6-speed manual.
*Amounts based on MSRP in April 2018. Prices are subject to change.


Some systems, like Volkswagen’s Lane Departure Warning with Lane Assist, can determine if you’re about to drift into the next lane, and either warn you or correct the steering.


What is it?

Lane departure warning (LDW) systems use a camera to monitor your vehicle’s position in the lane, and if it senses you’re drifting too close to the edge, it can warn you to get back in the center. The system is sometimes combined with a lane keep assist feature, which can physically steer the car back toward the center, using either the electronic power steering or the brakes.

What are the pros?

As the name implies, a LDW system helps you stay in your lane, reducing the risk of an accident should you find your concentration waning.

What are the cons?

Most systems are still relatively new, having only been on the road for a few years, and are yet to be perfected. If lane markings aren’t optimal, or the weather is inclement, the car’s camera could have a hard time accurately gauging the lane.

According to the IIHS, owners find LDW systems more annoying than other driver aids, causing them to turn it off at a higher rate. As a result, LDW’s real-world benefits are less obvious than those of emergency braking systems.

What should you look for?

There are several variables that factor into the system’s effectiveness. Some use one camera, while others use two to create a 3D view of the surroundings. Also, pay attention to the specific system you’re looking at: lane change alert and lane keep alert are different, for example, as is lane departure warning and lane keep assist. Specifically for a lane keep assist system that intervenes when you’re about to drift into another lane, look for one that uses the power steering to guide the car back to the middle of the lane, as it’s more robust than one that simply uses the brakes.
If you want the best of the best, a handful of high-end systems now offer automated lane changes, which works like a lane keep assist system but will change lanes for you when you hit your turn signal.

How much does it cost?

Lane departure warning, and to a greater degree lane keep assist, are among the more advanced systems on the market. As a result, it’s usually part of an upgrade package, and sometimes part of a more expensive second-tier of driver aids. On the 2018 Nissan Rogue crossover, for example (shown in top image), Lane Departure Warning and Intelligent Lane Intervention are both included at no extra charge, though only available on the range-topping SV trim.


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Aaron Miller
As a veteran automotive journalist, I have been fortunate enough to drive some of the most desirable cars on the planet and get to know some of the most important people in the industry. Before joining Capital One, I served as the Cars Editor for a major national website, and covered industry news and analysis for well-known automotive-specific sites. I also wrote feature articles and reviews for niche enthusiast websites. I’ve been obsessed with cars since—literally—before I can remember, with my collection of die-cast and slot cars taking center stage during my formative years. Simply put, for me, working isn’t really “work.”