Lane keeping assist (LKA)

Two systems get confused constantly, and the difference is exam material: a lane departure warning only warns, while a lane keeping assist actually steers.

How does it work?

A camera behind the windscreen reads the lane markings. Cross a line without indicating and the system intervenes. With a lane departure warning (LDW) that stays a beep, a light, or a vibration in the wheel or seat. With lane keeping assist (LKA) a gentle steering correction back toward the middle of your lane follows too.

Indicate properly and the system stays quiet. You are then changing lanes deliberately. Some cars have a more extensive variant that actively keeps you centred between the lines.

What the CBR asks about this

• You respond to the warning calmly: check your position and steer back gently. A jerk at the wheel makes the situation more dangerous than the warning itself.
• You switch the system off when the situation calls for it, for instance when markings are under snow or at roadworks with double markings.
• You check before the drive that the windscreen is clean where the camera sits. A dirty or fogged screen blinds the system.

This system falls under these guidelines from the Rijprocedure B:

Limitations: This is where the exam questions are

No visible markings, no function

Snow, wear, spray or a freshly surfaced road without lines: the camera has no reference. The system drops out or, worse, follows the wrong line.

Roadworks with double markings

Yellow and white lines together are a classic problem. The camera may follow the old white line while you are supposed to follow the yellow one.

LKA nudges, it does not steer for you

The correction is deliberately weak so you can always override it. Hands off the wheel is therefore not an option: the system will not keep the car on the road by itself.

Sharp bends are too much to ask

In a tight bend or a quick change of direction the correction is not enough and you simply run wide.

Three practice questions

Open one for the answer and the explanation.

What is the difference between LDW and LKA?

• LDW only warns; LKA warns and gently steers
• LDW steers; LKA only warns
• There is no difference, they are two names for the same system
• LDW works on motorways, LKA in built-up areas

Correct answer: LDW only warns; LKA warns and gently steers

Explanation: A lane departure warning (LDW) gives a signal or vibration. Lane keeping assist (LKA) adds a gentle steering correction. Names differ per brand: one of the principles in the Rijprocedure B.

You drive onto a snow-covered road where the markings are no longer visible. What do you do with your lane keeping assist?

• Switch it off; without visible lines the system can steer wrongly
• Leave it on, two observations are better than one
• Leave it on but drive more slowly
• Switch it off and disable your ESP as well

Correct answer: Switch it off; without visible lines the system can steer wrongly

Explanation: You switch an assistance system off when the situation requires it. Without a reliable reference the camera can latch onto the wrong line.

The wheel vibrates because you are crossing the line without indicating. What do you do?

• Check your position and steer calmly back to the middle
• Steer back forcefully so the warning stops
• Leave it to the system, it corrects fully
• Switch the lane assist off so it stops vibrating

Correct answer: Check your position and steer calmly back to the middle

Explanation: You respond to warnings according to the rijprocedure: correct calmly, based on your own observation. LKA’s correction is gentle and does not take over the steering.

Written on the basis of the official CBR Rijprocedure B. These are not real exam questions.