Back in 2005 when I was in my early twenties I had spent a Sunday hanging out with friends at a braai (aka a barbeque). I was watching the meat sizzle on the fire with a beer in one hand while I sampled (read as devoured) any and all snacks in sight. I’d skipped breakfast that morning because my girlfriend at the time kept claiming she was almost ready for us to go to the braai. Needless to say, she took her time and my stomach had been growling all the while.

After I’d eaten my fair share of food, I was feeling that “magie vol, ogies toe” feeling, which is an Afrikaans phrase for when you eat a full meal and feel the need to nap afterwards. I fought this feeling with a great deal of effort because I knew if I had a late afternoon nap I’d be awake all night. And so I carried on with my day, fighting the nagging urge to sleep.

At around 8pm that night I had to take my girlfriend home. The problem was she lived 50km away and I was still tired from having eaten so much at the braai, but she didn’t have any work clothes with her and so we left for her place. Most of the drive was done on highways which made for a very boring drive. We got to her place, said our good-byes and I started my journey back home.

Now, as you might imagine, I was feeling incredibly tired and if I’d been smart I would have stayed over at my girlfriend. However, being the young male that I was, my ego stepped in and convinced me to drive home. As I was driving down the last stretch of highway I could feel my eyelids getting heavy. The offramp that lead to my place was no more than 20 seconds ahead of me and that’s when  it happened. I fell asleep at the wheel. I jolted awake maybe half a minute later and I was lucky to find myself alive. I was still in my car which was free-wheeling along the left side of the offramp that lead towards my house. Had the offramp not been there my car would have driven off the road and likely done the equivalent  of Olympic level gymnastics.

Now there aren’t many people who can claim to be so lucky. A large majority of people have been in fatal accidents due to falling asleep at the wheel. With the advancements in car safety technology and research, some vehicle manufacturers have started equipping their vehicles with what’s known as a lane departure warning (LDW) system.

Warning, assist and self-centering

LDW systems come in three different forms. However, they all perform the same basic functionality which is to warn the driver when the vehicle is moving out of the lane they’re driving in. They do this with the help of a camera mounted behind the rear view mirror that watches the markings on the road and beeps repeatedly if the car starts drifting.

  1. Lane departure warning is the original and most basic of the three. This does exactly as described above. It’s simply a warning and the driver will need to take corrective measures.
  2. Lane keep assist will help steer your car back into the lane if it detects it driving over lane markings. It’s important to note that this is only an assistance to the driver and not a substitute for driving. The driver needs to make sure to center the car in the middle of the lane.
  3. Lane centering assist is the most modern of the three. It makes sure your car is in the center of your lane in addition to doing the job of the previous two. This system only works if it can sense your hands on the steering wheel.

What you need to know

These systems vary between vehicle manufacturers and how they differ could be critical to driver satisfaction.

There is a minimum speed requirement before the LDW system kicks in. This can vary anywhere between 50-65km/h depending on the manufacturer, which is a clear indication that it isn’t meant for low-speed driving.

How the system warns you can also differ between manufacturers. Some systems have audible warnings which beep at the driver to alert them that the vehicle is drifting out of the lane. Others have something called haptic feeback, which is essentially a warning by touch. It does this by vibrating the steering wheel or the driver’s seat. And lastly, there are visual warnings. Virtually every system has some sort of visual warning that appears on your instrument cluster.

Some manufacturers have designed their LDW system to allow the driver the option to change when the warning should go off. The typical options are:

  1. Before the vehicle reaches the lane marking
  2. When the vehicle is on the lane marking
  3. Once the vehicle has gone over the lane marking

Obviously the early alert option is the safest, but this will mean more frequent alerts if you’re not paying attention which some drivers may find annoying.

The automatic steering used in lane keep assist and lane centering assist can be annoying if you’re changing lanes without indicating. However, you can override it by turning the steering wheel harder than the system is.


LDW isn’t 100% perfect. There are situations where LDW won’t work as well as you’d expect (or even at all), such as roads with lane markings that have faded; and in weather where visibility is bad. Don’t let this fool you into thinking these systems are gimmicks though. Having LDW is far safer than not having it. And having it in conjunction with some of these other safety features will further increase your well-being.