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An illustration of Nissan’s backup sensor system.

This is the third article in a series on modern automotive technology.

A growing number of new cars are gaining the ability to automatically brake on their own when they detect trouble in front of them. But what about behind them?

Backup cameras became mandatory in new vehicles in Canada in May in an effort to cut down on rear collisions, but they’re only the first step in preventing accidents while reversing.

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Rear-collision intervention systems promise to take that protection further by offering emergency automatic braking for cars when they are backing up.

What is it?

Rear-collision intervention is a system that automatically applies brakes when the vehicle is moving in reverse into oncoming traffic or other obstacles.

It’s known by various names depending on manufacturer – Rear Cross Traffic Collision Avoidance Assist with Hyundai, Intelligent Brake Assist with Nissan and Rear Cross Traffic Auto Brake with Toyota, for example – but in each case, its purpose is to help prevent drivers from backing up into accidents.

“This is the next step,” says Scott Pak, senior product planning manager for Nissan North America. “In the event that they’re not paying attention, the car will brake for you.”

How does it work?

Rear-collision intervention systems use a blend of sensors to detect threats, starting with radar. The radar sensors, built into the sides of the rear bumper, are typically the same as those used in blind-spot detection features. They can sense vehicles approaching directly from behind or from the driver’s flanks.

Some systems also incorporate cameras situated around the car while others use sonar. Nissan, for one, uses rear sonar in its Infiniti vehicles because it is good at distinguishing between cars and people, Pak says.

Regardless of which sensors are used, the vehicle automatically applies brakes and issues visual alerts and warning sounds to the driver in situations where a car, pedestrian or other obstacle is detected.

The ability to detect obstacles behind the car has been around for a while, but the addition of automatic braking is relatively new, which is why only a few vehicles have the function so far.

Nissan, for example, offers the braking capabilities as an option in some of its 2018 Infiniti and Armada cars, with an eye to expansion to more future models soon. Toyota has it in the 2018 Camry and Lexus LS, RX and NX models, while Hyundai is offering the auto braking in its 2019 Santa Fe.

“When you start backing up, you don’t know what you’re backing into,” says Terry Tizard, manager of Hyundai Performance Academy for Hyundai Canada. “This gives you a little bit of reassurance that you can have some visibility, even if you can’t see.”

What is it for?

High-speed collisions are responsible for the majority of car fatalities, but relatively lower-speed backups contribute their share, too. U.S. estimates figure about 200 people are killed each year as a result of cars reversing.

Improperly backing up also results in plenty of fender benders, particularly in parking lots and driveways. The problem is being compounded as North Americans increasingly choose to drive SUVs and trucks, which have even more limited rear visibility than their smaller counterparts.

Automakers say rear-collision intervention systems can help stem some of these problems by intervening when the driver can’t see what they’re backing into.

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“There’s a lot going on and a lot to process,” Pak says. “This is another step to minimizing injuries and fatalities.”

Toyota says the function is particularly useful in North America, where – according to an internal study – drivers are more likely to pull into parking spots frontward. The automaker doesn’t have an explanation as to why, but says that drivers in Europe and Asia are more likely to back up into spots.

Rear-collision intervention is thus a natural antidote to this odd North American preference.

“It helps the driver see and detect cars and obstacles in the rear that are [otherwise] very difficult to see,” says Hideki Hada, executive engineer in the research and development division of Toyota Motor North America.

What are the rules?

There are no requirements in North America yet for rear-collision detection or intervention, but some automakers believe it’s only a matter of time before they become mandatory given the trajectory of other similar technologies.

Backup cameras, for example, started to hit the market around 20 years ago. The U.S. National Highway Traffic Safety Administration in 2014 decided to make them mandatory starting this year, followed by Transport Canada. Many automakers have been installing them as standard for years now in preparation.

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Rear-collision intervention requirements could arrive faster given their potential benefits.

“There’s a consolidated effort to adopt this quite quickly,” Pak says.

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