Why must ADAS be calibrated after a windscreen replacement?

Short answer: The ADAS systems — emergency braking, lane keeping, adaptive cruise control, sign recognition — are driven by a camera mounted behind the windscreen. Replace the glass and the camera's position and angle change ever so slightly, and at the distance the camera works, "ever so slightly" quickly becomes metres. That is why the camera must be calibrated after a windscreen replacement, so the systems see the road as they should.

What is ADAS?

ADAS stands for Advanced Driver Assistance Systems — the driver support that comes with most newer cars: automatic emergency braking, lane keeping assist, adaptive cruise control and sign recognition. The brain of many of them is a camera at the top of the windscreen, continuously reading lanes, cars, pedestrians and signs.

Why a windscreen replacement disturbs the camera

The camera is calibrated to know exactly where it points relative to the car's direction of travel. When the windscreen is replaced, the bracket and glass are never mounted one hundred percent identically — it can be a matter of millimetres and fractions of a degree. At ten to fifty metres, where the systems make their decisions, that deviation is enough for the camera to misjudge distances and lanes. The insidious part is that the car rarely warns about it: the systems appear to work as before, just with the wrong "eyesight".

Static and dynamic calibration

• Static calibration is done in the workshop: the car is positioned precisely against the manufacturer's target boards, and the camera is adjusted with diagnostic equipment.
• Dynamic calibration is done driving on the road with the equipment connected, while the camera relearns its references.
• Which method — or combination — is required is set by the car manufacturer per model.

When else is calibration needed?

Not only after windscreen replacements. Calibration can also be required after front-end damage, work on wheel alignment or suspension, and when the driver assistance systems report faults — anything that changes the relationship between the camera's view and the car's actual direction of travel.

What we see most often at the workshop

The most common thing we meet is cars that have had the windscreen replaced without calibration — often because the owner did not know the car had camera-based systems. Everything seems normal, until the lane keeping starts tugging at the wheel on a straight road or the emergency braking beeps for no reason. With us, calibration is part of the windscreen replacement when the car has ADAS — that is how the job should be done.

Got a crack in the windscreen, or recently had it replaced without calibration? Call us on 41 17 32 24.