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Blind-zone alerts light up in the left mirror to warn the driver about changing into the left lane.

Eddie Wren says there are 11 blind spots on a typical sedan and 13 on most SUVs and minivans.

And that, according to the president of Advanced Drivers of America who is a former highway patrol officer in Britain, doesn't even include things that are hidden from the view ahead of the hood, below the trunk or tailgate or below window level.

Auto makers have been equipping some vehicles with blind spot warning systems since 2007. Various technologies are utilized, including ultrasonic and radar sensors. These monitor the sides and rear of the vehicle for traffic approaching from behind. Notification may be audible and/or visual – in the form of flashing lights in the side mirrors.

Chrysler products equipped with blind-spot monitoring, including the Jeep Cherokee, use dual ultra-wide band radar sensors to aid drivers when changing lanes, passing or being passed. Blind-spot vehicle presence is indicated via illuminated icons in the side-view mirrors, and an audible chime.

Porsche's Lane Change Assist, activated by a button on the driver's door, also uses radar sensors to monitor the blind-spot area behind the vehicle. Depending on the situation, an LED signal in the door mirror indicates when the system senses an approaching vehicle. If the turn signal is then activated, the LEDs flash.

The warning indicator on the left mirror assists the driver with changing into the left lane, and the warning indicator on the right mirror assists with changing into the right lane.

Blind-spot or blind zone warning lights are just one technology among many categorized as driver-assist systems, all of which are designed to help drivers avoid collisions.

"We did an analysis looking at several different types of crash-avoidance systems, and we lumped them together – forward collision warning, lane departure warning, blind spot detection and adaptive headlights," says Russ Rader, senior vice-president of communications for the U.S. Insurance Institute for Highway Safety (IIHS). "If those systems work as intended, they could prevent a lot of crashes. Our analysis shows that those systems, together, if they were on all vehicles, could prevent about one in three fatal crashes and about one in five injury crashes."

So why aren't blind spot warning systems mandatory equipment on new vehicles?

"That's the potential of the systems; the issue is how are they really working in the real world," Rader asks. "And for blind zone detection, the jury is out. We don't know yet. They're relatively new and we're still gathering data.

"They have a lot of promise to reduce crashes, and we're seeing some features like front crash prevention and adaptive headlights and, of course, older technology like electronic stability control (ESC) – those are proven crash-avoidance features that are reducing crashes."

ESC is one example of crash-avoidance technology that was mandated after research revealed how effective it can be. In the United States, the IIHS found that ESC could help avoid 41 per cent of single-vehicle collisions.

According to Transport Canada, ESC may reduce the number of crashes involving a loss of control by light-duty vehicles by 29 per cent. ESC has been mandatory in Canada since the 2012 model year.

However, even with the aid of driver-assist systems, engaged and conscientious motorists are always a prerequisite.

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