Replacing or repairing windscreens used to be a relatively simple and quick process. However, the growing prevalence of advanced driver assistance systems (ADAS) and their use of windscreen-mounted sensors means this may no longer always be the case.

Safety technologies such as autonomous emergency braking (AEB) and lane-keeping assist use radar, laser or camera sensors which are often located behind a car’s windscreen. The same applies to more convenience-oriented features such as adaptive cruise control.

Vehicle safety consultancy Thatcham Research says windscreen-mounted ADAS technology is currently fitted to approximately 6% of vehicles on UK roads, with this proportion likely to rise to 40% by 2020.

These figures are likely to be much higher for fleets as the age of their vehicles will be much less than the overall UK car parc. This means fleets have to be aware of the implications windscreen replacement or repair can have on vehicle safety, as well as ensuring the sensors are properly calibrated.

“The importance of [recalibration] being undertaken correctly cannot be underestimated,” says Frank Harvey, head of bodyshop operations at the National Association of Bodyshops (NAB).

“Without correct calibration, an ADAS will read and process wrong information meaning the vehicle safety system will not operate properly.”

This could create a significant and unnecessary risk for drivers: Euro NCAP research shows that a correctly working AEB system leads to a 38% reduction in rear-end collisions.

The prospect of a collision not being avoided because of incorrectly calibrated ADAS sensors means fleets should have an effective policy in place to avoid a “legal minefield”, says Phil Homer, operations director at Nationwide Windscreens.

“For example, a sales rep might leave a company and return their car on a Friday after replacing its windscreen earlier that week without bothering to have the ADAS recalibrated,” he says. “If another rep starts driving that car the following week and subsequently has an accident that could have been prevented by the ADAS, then there’s clearly a major problem.”

Auto Windscreens aims to schedule recalibration appointments at the same time as windscreen replacements, but “if recalibration is not carried out immediately, drivers are asked to sign a disclaimer advising them not to rely on any of their ADAS technology until recalibration has been completed”, says Rupert Armitage, managing director of Auto Windscreens.

“We decided to adopt this approach as it really is about duty of care when it comes to fleets.

“If the vehicle has been to an approved retailer for recalibration and there is then an issue with any ADAS components owing to this or the glass replacement, we have a robust, transparent trail to provide proof that we and the fleet have done everything possible to protect drivers.”

So when should the sensors be recalibrated? “At present, all vehicle manufacturers require the resetting – which is also known as recalibration – of the sensors following a collision or replaced windscreen,” says Andrew Miller, chief technology officer at Thatcham Research and chairman of Euro NCAP. “At Thatcham, we support this position.”

Manufacturers also advise recalibration should be performed after a wheel alignment and if a sensor has developed a fault, been disconnected or been partially removed.

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