Lane Departure vs. Lane Keeping vs. Lane Centering Tech

Advanced driver assistance systems (ADAS) are innovative technology features that use sensors, cameras, radar, and lidar to keep you safe on the road by reducing the impact force of an accident or avoiding a collision altogether. But with so many different ADAS systems available these days, it can be confusing for consumers to differentiate between them. 

Lane Departure and Keeping Assistance BMW X5

Photo: Christian Wardlaw

A good example of this confusion is the safety tech that helps prevent drivers from drifting around on the road. There are three primary types of systems in this category: lane-departure warning (LDW), lane-keeping assistance (LKA), and lane-centering assistance (LCA). 

Though the overall goal of each system is the same, they operate differently to keep vehicles within the driver’s intended lane of travel. But the distinctions between them can become blurry, especially when each automaker has its own naming convention for each system (i.e., Honda’s nomenclature for lane keeping assistance is “Road Departure Mitigation” while its lane-centering technology is called “Lane Keeping Assist”). 

The best way to understand how each of these systems works is to first define them in a standardized way without the proprietary names assigned by manufacturers.

What is Lane-departure Warning?

Lane-departure warning is the most basic type of lane monitoring technology. As the name denotes, this system alerts the driver when the vehicle is drifting out of its lane without using a turn signal. 

LDW does this by using a camera at the front of the car to monitor the trajectory of the drive path while also identifying road divider lines. The alert to the driver generally comes in the form of an audible warning and is often in tandem with a visual cue such as an indicator light or an illuminated icon in the gauge cluster. Many systems also provide haptic warnings, such as vibrations through the steering wheel. 

Since this is a passive system, it does not actively intervene to prevent lane departure. Instead, it relies on the driver to make the necessary adjustments to steering and braking to get the car back into the intended lane.

What is Lane-keeping Assistance?

Lane-keeping assistance utilizes the functions of LDW, but this technology is active instead of passive. This means LKA semi-autonomously prevents a vehicle from drifting into another lane rather than just alerting the driver that the car is off-course. It makes this correction by gently employing automatic steering and/or braking on the opposite side of the car in order to bring the vehicle back toward the center of the lane. 

Although the driver is still in overall control of the car, they will feel the steering wheel adjust on its own based on lane divider information the system is acquiring from the front-mounted camera. They may also feel the braking system “tug” the vehicle back toward the center of the lane. Audible and visual alerts generally accompany LKA’s functionality.

Sometimes, automakers use this same technology in conjunction with a blind-spot warning system. If a driver ignores the blind-spot warning and attempts to make an unsafe lane change, the steering and braking systems may intervene. These are often called active blind-spot warning systems.

What is Lane-centering Assistance?

Lane-centering assistance is currently the highest level of lane monitoring technology. This system proactively keeps the vehicle centered within the lane it is traveling. It utilizes automatic steering functionality to make constant adjustments based on road marking information from the front-mounted camera. 

LCA systems generally work in tandem with adaptive cruise control and LKA to give a car semi-autonomous capability. In these cases, the combined technologies qualify as a Level 2 automated driving system by the Society of Automotive Engineers (SAE).

Hands-free driving systems, such as Ford BlueCruise, rely on LCA to operate. They allow a driver to remove their hands from the steering wheel on specific, approved roads, using the adaptive cruise control, LCA, and in most vehicles with this kind of technology, sensitive driver monitoring systems to allow hands-free driving. However, because the driver must pay attention and remain ready to take full control at any time, this hands-free technology remains a Level 2 system. 

Summary

Lane-departure warning, lane-keeping assistance, and lane-centering assistance offer different degrees of ADAS lane monitoring technology to help prevent drivers from making an error that could lead to an accident. 

While some are more intrusive than others, they can all be turned on or off depending on the driver’s preference. The most sophisticated lane monitoring systems provide the ability to adjust sensitivity levels and the types of warnings, giving a driver an opportunity to fine-tune system behavior.

Although there are many iterations of each system, from automaker to automaker, each one ultimately brings peace of mind and an elevated sense of safety to the driving experience. That said, until new Level 3 ADAS such as Mercedes-Benz Drive Pilot gain regulatory approval for use in U.S. highways, none of these systems should ever serve as a substitute for a driver’s attention to the road ahead.