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How do blind spot monitoring systems work?

How do blind spot monitoring systems work?

Because our eyes face forward, we cannot see what is behind us. And, unlike owls, we cannot turn our heads 270 degrees. These limitations, as well as vehicle construction, lead to blind spots. The most dangerous blind spots are right around the rear bumper to the sides. Motorcycles, small cars and even trucks can “hide” in those places. At highway speeds, a lane change can be disastrous if a vehicle “comes out of nowhere.”

Blind-spot car crashes are all too common, according to the Insurance Institute for Highway Safety (IIHS). Ignoring blind spots causes upward of 350,000 car crashes every year. Volvo introduced blind-spot monitoring technology in 2003. Soon after, other automakers began offering similar technology. Blind spot monitoring can make the roads safer, but what is it, and how does it work?

5 Blind Spot Solutions

Early in automotive history, open cars had no blind spots. As long as the driver was able to turn his head (Solution #1), he could see everything around him. With the development of closed vehicles, blind spots became more of a problem.

 

One solution to the problem, automotive mirrors (Solution #2), have been around for more than 100 years. These became common a couple of decades after the invention of the automobile. The premise is simple, a way to look behind and to the sides without turning your head. The rearview mirror gives you a general view behind the vehicle. Wing mirrors, or side mirrors, give you a general view of the sides of the vehicle. Wide-angle mirrors and blind-spot mirrors (Solution #3) can improve visibility, too. Either way, proper adjustment is critical.

 

Properly adjusted mirrors can almost eliminate blind spots. It may seem to be a simple thing to adjust the mirrors, but many drivers don’t know how to do this. Instead of adjusting for the view, they look for the side of the vehicle in the mirror. This leaves glaring blind spots in which almost any vehicle can hide. This human error causes more than 94 percent of car crashes, according to the National Highway Traffic Safety Administration (NHTSA).

Side-view cameras (Solution #4) are a recent innovation and work like backup cameras. Side-view cameras activate with the turn signal. Using a small camera, this system displays a wide-view shot of the lane beside the vehicle.

To make up for human faults, automakers introduced blind-spot monitoring systems (Solution #5). As mirrors are informative devices, blind-spot monitoring gives drivers more information. With more information, drivers can make better decisions while on the road. Still, how does blind spot monitoring work?

How Blind Spot Monitoring Works

Blind spot monitoring is a two- or three-step process. Two-step, or “passive,” BSM systems detect obstacles and notify the driver. Three-step or “active” BSM systems can evade obstacles.

Detection. Blind-spot monitoring systems may use sonar, lidar or cameras to detect objects. They may activate at certain speeds or when the driver activates a turn signal. Read the owner’s manual for more information on your specific year, make and model, and BSM type.

Notification. If these sensors detect an obstacle, such as another vehicle, BSM notifies the driver. Automakers enable BSM to use various methods to notify the driver of obstacles in the blind spot. Audible notifications include alarms, beepers and buzzers. In most situations, audible notifications are easy to hear. Road noise, wind noise and the radio might drown them out. Tactile notifications include vibrating the steering wheel or seat. In high-noise situations, tactile notifications might work better. Visible notifications include dash warning lights or mirror warning lights. Because the driver should be looking at the mirrors when making lane changes, visual notifications can be effective.

Evasion. A few vehicles can evade objects in their blind spots. If the driver doesn’t take action, active BSM can nudge the vehicle away from the obstacle. This is the same technology that enables lane keeping and lane centering to work.

How Well Is Blind Spot Monitoring Working?

Like all driver assistance technologies, blind spot monitoring cannot replace good driver habits. Speeding or failure to signal lane changes can defeat BSM systems, leading to car crashes. Failing to keep sensors clean and clear of obstacles also can negate BSM benefits. Still, IIHS researchers determined BSM technology could reduce blind-spot crashes by 14 percent. This means blind-spot monitoring could prevent about 50,000 car crashes every year. This is a significant margin but demonstrates all drivers need to drive better.

Whether you drive a BSM-equipped vehicle or not, start by adjusting your mirrors. Your rearview mirror and side mirrors should overlap only by a small margin. The first time you try this, have a friend stand at the left-most position in your rearview mirror. Then, adjust the left wing mirror until you can see your friend only on the far right. Repeat this for your right wing mirror. Your friend should be visible in the rearview mirror far right and right wing mirror far left. These adjustments give you a wider view and can completely eliminate blind spots on most vehicles. Small blind-spot spot mirrors also can help. These adjustments reduce the need for you to turn your head very much, but it might take time to become accustomed to it.

If you drive a BSM-equipped vehicle, read the owner’s manual to discover how your blind-spot monitoring system works. Aftermarket blind-spot monitoring systems also are available for some older vehicles. Keep BSM sensors and cameras clean and free of snow, ice and grime. True, BSM can’t replace good driving, but it can’t hurt to have a little more information to help you drive better. If you still have questions about your blind-spot monitoring system, be sure to ask your dealer.

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