General Motors has been at the forefront of integrating active safety technology into its vehicles. Outside of Adaptive Cruise Control, which we will profile in a separate column, the most prominent active safety tech is (arguably) Lane Departure Warning (LDW) and the new Lane Keep Assist (LKA) features. The former made its debut as an option on some 2014 model year GM vehicles in conjunction with GM’s Safety Alert Seat, while the latter has become available in select models and trim levels (or option packages) on 2015 model year Cadillacs such as the 2015 ATS, 2015 CTS, and 2015 XTS.
What, exactly, do Lane Departure Warning and Lane Keep Assist do, and how do they work? Let’s find out.
Lane Departure Warning
The goal of the Lane Departure Warning feature is to help avoid crashes resulting from unintentional lane departures. The system provides a warning (either via a sound, a pulse in the Safety Alert Seat, or an indicator in the instrument cluster) if the vehicle is crossing a detected lane marking without using a turn signal in the lane departure direction.
Lane Keep Assist
Similar to Lane Departure Warning, the goal of Lane Keep Assist is to help avoid crashes due to unintentional lane departures. But whereas Lane Departure Warning solely provides a warning, Lane Keep Assist may actually assist staying in a lane by gently turning the steering wheel if the vehicle approaches a detected lane marking without using a turn signal in the lane departure direction. Lane Keep Assist may also provide a Lane Departure Warning system alert as the lane marking is crossed.
The system will not assist or provide a Lane Departure Warning alert if it detects that you are actively steering. It’s possible to override Lane Keep Assist simply by turning the steering wheel.
How It Works
Lane Keep Assist uses a camera sensor to detect lane markings between speeds of 60 km/h (37 mph) and 180 km/h (112 mph). The camera sensor is located on the windshield ahead of the rearview mirror.
Enabling & Disabling
To activate or deactivate Lane Keep Assist on Cadillac vehicles, press the “A” to the left of the steering wheel.
When on, A is green if LKA is available to assist and provide LDW alerts. It may assist by gently turning the steering wheel and displaying A as amber if the vehicle approaches a detected lane marking without using a turn signal in that direction. It may also provide an LDW alert by flashing A in an amber color as the lane marking is crossed. Additionally, there will be three beeps, or the driver seat will pulse three times, on the right or left, depending on the lane departure direction.
The Lane Keep Assist system does not continuously steer the vehicle.
If the system does not detect active driver steering, the vehicle will provide an alert and chime. To dismiss, simply move the steering wheel.
If the Lane Keep Assist system is not functioning properly when lane markings are clearly visible, cleaning the windshield may help.
In addition, Lane Keep Assist assistance and/or Lane Departure Warning alerts may occur due to certain road conditions, such as tar marks, shadows, cracks in the road, temporary or construction lane markings, or other road imperfections. This is normal system operation, and the vehicle does not need to be serviced if you experience these issues. GM recommends turning Lake Keep Assist off if these conditions continue.
Keep in mind that Lane Keep Assist is not infallible, and may not keep the vehicle in the lane or give a Lane Departure Warning alert, even if a lane marking is detected.
According to GM, Lane Keep Assist and Lane Departure Warning systems may not:
- Provide an alert or enough steering assist to avoid a lane departure or crash
- Detect lane markings under poor weather or visibility conditions, or if the windshield or headlamps are blocked by dirt, snow, or ice, if they are not in proper condition, or if the sun shines directly into the camera.
- Detect road edges
- Detect lanes on winding or hilly roads
And if Lane Keep Assist only detects lane markings on one side of the road, it will only assist or provide a Lane Departure Warning alert when approaching the lane on the side where it has detected a lane marking.
Lastly, GM says that using Lane Keep Assist while towing a trailer or on slippery roads could cause loss of control of the vehicle and a crash. Turn the system off.
When the LKA or LDW systems don’t work properly, the system performance may be affected by:
- A close vehicle ahead
- Sudden lighting changes, such as when driving through tunnels or direct sunlight on the camera sensor
- Banked roads
- Roads with poor lane markings, such as two-lane roads
Given the various nuances with the LKA and LDW features, we’d say that it’s always a good idea to keep the windshield, headlamps, and camera sensors clean and in good condition, and avoid using Lane Keep Assist in bad weather conditions, or on bad roads.