Avoiding crashes with self-driving cars

    Today's crash-avoidance systems are the mile markers to tomorrow's autonomous vehicles

    Published: February 2014

    This scenario may not be as far away as you think: You get into your car in the morning and start to back out of the driveway. Suddenly you hear a warning sound, telling you that a vehicle coming down the street will intersect your path. Your car applies the brakes on its own while the vehicle passes harmlessly by. You continue to drive and get on the highway, then press a button, take your hands off the wheel, and reach for your coffee. The car takes over the steering, centering itself in the lane and following the vehicle ahead at a safe distance. As you reach your exit, you take back control and get off the highway. Another car cuts you off at an intersection, however, and your car immediately sounds an alert and applies the brakes, avoiding a collision. When you reach your destination, you get out of the car and press a button, and the vehicle parks itself.

    No, that isn't science fiction. Most of the technology needed to make the scenario an everyday reality already exists, either in today's production vehicles or in prototypes being tested on public roads (see "Behind the Wheel of a Self-driving Car," below). Though there is a lot of talk about self-driving, or autonomous, cars coming at some indefinite future, those types of real-world crash-avoidance systems are already taking us step-by-step toward that goal.

    At this time, for example, we're testing the redesigned 2014 Mercedes-Benz S550 at our track. Among its many features is a system, designed as an aid in congested traffic, that allows the car to virtually drive itself. It automatically maintains a set distance behind a car in front, speeding up and slowing down as necessary. It keeps itself centered in the driving lane and brakes when necessary to maintain a safe distance from other vehicles. All that it requires is for the driver to keep one hand on the steering wheel. The new BMW X5 SUV has similar systems. And additional models with those and even more advanced features will be showing up every year.

    Taking control

    Park assist

    Research shows that 90 percent of crashes are caused by human error. That's why the National Highway Traffic Safety Administration (NHTSA) and every major automaker are increasingly focusing on systems that allow the vehicle to become a partner in the drive by monitoring a car's surroundings, warning the driver of danger, and even taking control of the car in some situations. "For the past 40 years, we've been working on protecting people from the crash," says David Strickland, NHTSA's former administrator. "This is the new North Star, making sure the crash never happens."

    Overall, the advanced safety systems are just getting warmed up, but they are already showing promise in reducing the number of accidents and fatalities on today's roads. Here's a rundown of advances you can find in showrooms that are also the building blocks of tomorrow's autonomous cars.

    Looking down the road. One of the most promising features is forward-collision warning (FCW). It uses sensors or cameras to monitor the distance between your car and one in front. If the system calculates that you are at risk of hitting that vehicle, it alerts you through an audible and visual warning. It can also pre-charge the brakes to provide maximum braking power to the driver, and some systems tighten the seat belts in preparation for a collision. A few FCW systems go a step further by automatically braking the car if the driver does not respond quickly enough. Volvo's City Safety and Subaru's EyeSight systems, for example, can do that at speeds up to 30 mph. Even if a car can't avoid a crash altogether, it can reduce the severity of the impact and the chance of injury and damage by reducing the vehicle's speed.

    The Insurance Institute for Highway Safety (IIHS) has seen a 7 percent reduction in crashes for vehicles with a basic forward-collision warning system, and a 14 to 15 percent reduction for those with automatic braking. "Even in the cases where these systems failed to prevent a crash, if there's automatic braking going on, or if the driver does brake in response to a warning, that crash is going to be less severe than it would have been otherwise," says David Zuby, senior researcher at IIHS. Because the effectiveness of FCW systems can vary from one model to the next, IIHS recently began testing cars equipped with them. It factors those results, along with its various crash tests, into whether vehicles earn its coveted Top Safety Pick+ designation. You can review its results by going to iihs.org. NHTSA does not evaluate individual systems, but it does list which models have FCW on its website, at safercar.gov, along with its own crash-test results.

    FCW is standard on many luxury cars, and it's beginning to show up as an available feature on some mainstream models, such as the Chevrolet Traverse, Ford Edge, and Honda Accord. Automatic braking isn't as widely available in lower-priced models, but it's an option in the redesigned Mazda3 s Grand Touring and Subaru Forester. The Jeep Cherokee also provides limited autonomous braking.

    An extra set of eyes. Many crashes occur when a car inadvertently runs into an unseen vehicle while changing lanes. A blind-spot monitoring system is designed to prevent that by monitoring the area next to and behind the car. If a vehicle is present, it will illuminate a warning light in or near the side-view mirror. If you activate a turn signal while a car is there, the system could send a stronger alert, such as a blinking light or an audible warning, to tell the driver that it's unsafe to move over.

    Though that feature is widely available and has worked well in vehicles we've tested, studies haven't been able to link it to a reduction in crashes.

    A rear cross-traffic alert system is often paired with blind-spot monitoring because they use the same sensors. That system helps detect approaching vehicles that are crossing behind your car as you're backing up. An alert sounds, and if the vehicle is equipped with a backup camera and display screen, a visual warning may also appear. It's a useful feature in parking lots or when backing out of your driveway. The Infiniti QX60 and Jeep Cherokee can even apply the brakes.

    Stay the course. Lane-departure warning (LDW) is designed to help prevent a sleepy or distracted driver from accidentally drifting out of his or her lane. It uses cameras and radar to detect lane markings and triggers a warning if the car starts to leave its lane without a turn signal being activated. Some advanced systems can take corrective steering action to help keep the vehicle on course. The Jeep Cherokee, for example, employs what feels like a tug on the steering wheel to direct the car back into the proper lane. The Mercedes-Benz S-Class uses a vibration in the steering wheel to alert the driver, and it can apply the brakes to individual wheels if necessary. We prefer the Jeep's gentle nudge back into the lane rather than having the car slow down.

    There are some limitations to those systems because they rely on well-marked lanes that cameras and sensors can see. So if it's dark or the road is snow-covered, the system may not work. In addition, getting frequent alerts on narrower secondary roads, where you often cross the center line, can be annoying.

    NHTSA lists the vehicles that have the feature on its website. The IIHS, however, has not found a link between that type of system and reduced crashes in its insurance claims data.

    Go with the flow. Adaptive cruise control helps your car automatically maintain a set distance behind one in front. Though it has been around for some time, newer systems have more capabilities. Some, for example, will disengage and require the driver to take over if the vehicle in front is traveling below a certain speed. The BMW X5's system will stop the car completely if the vehicle in front stops for a short time. It then starts moving the car when the other vehicle resumes speed.

    Combining adaptive cruise control with steering assist and lane-monitoring technologies is the key behind Mercedes' congested-traffic system. In our evaluations, the system has worked well so far. But it's not meant to be a completely autonomous system. The driver needs to keep his eyes on the road and be ready to take back control when needed. If you remove your hand from the steering wheel, the S-Class sounds an alert after a few seconds.

    Pedestrian detection. In 2012 pedestrian deaths from motor vehicle accidents accounted for 14 percent of all crash fatalities. Though Volvo was the first automaker to bring pedestrian detection to its vehicles, others offer it as well. The systems can recognize a person in front of the car and automatically apply the brakes, if needed, before an impact. They're a good investment if you spend a lot of time driving in crowded areas because they have the potential to help you avoid hitting a pedestrian or reduce the chance of serious injuries to one. Some newer systems can also detect bicyclists. The forthcoming Volvo XC90, which is due out at the end of 2014, will offer a system that can detect pedestrians in the dark.

    Self-parking. Parallel parking is a challenge for many drivers. And more cars are available with a park assist feature that can help. The feature debuted in the 2007 Lexus LS, but it wasn't always foolproof (see our video). A number of automakers currently offer such systems, with more advanced capabilities. The 2014 Jeep Cherokee, for example, can help with both perpendicular and parallel parking.

    Bosch is working on a smart-phone app that will allow the driver to get out of the car, which will park itself, although he'll need to hold down the button on a cell phone while he monitors the parking. Valeo recently showed off a system that will automatically park the car, shut off the engine, and lock the doors when it's securely in a spot. The Bosch and Valeo systems are not yet available to consumers, but they're small steps toward full automation.

    Vehicle-to-vehicle communication. Although the technology is not yet available in production cars, NHTSA recently announced that it was moving toward mandating that vehicles come equipped with wireless systems termed "V2V" that would allow cars to "talk" to each other, exchanging speed and location data so that they can avoid accidents. Some automakers see the technology as a way to enhance the capabilities of autonomous cars.

    The cost of safety

    In our testing, we've had the opportunity to try out dozens of safety systems. We think they provide real benefits to drivers, but the devil is often in the details. That's why automakers are working hard to make sure their systems are intuitive and foolproof, and that drivers will respond to the warnings with the correct action. "We put a lot of time and energy into making sure we don't have a system that people want to turn off because it annoys them more than they feel it benefits," says Steve Kenner, Ford's global director of automotive safety.

    An IIHS field test found that 72 percent of people who tried multiple crash-avoidance technologies said they would want them in their personal vehicle. However, the cost can be an obstacle. Most of the systems come only as part of a large options package or on a model's higher, more expensive trim versions. That can add an average of $2,000 to the cost of a vehicle. And not every model offers all of the features.

    As word gets out about the benefits of those types of systems, automakers say consumer acceptance will grow, which will help to bring down the cost and make the safety advances more affordable.

    Behind the wheel of a self-driving car

    No hands, no feet
    Audi’s A7 prototype can drive itself in rush-hour traffic.

    While the major automakers are developing autonomous vehicles behind closed doors, we were able to experience  Audi's latest prototype at Las Vegas' CES show in  January. California, Florida, Michigan, and Nevada are the only states, along with Washington, D.C., that currently allow companies to test such vehicles on public roads.

    Audi's  A7 test car is equipped with the company's traffic-jam assist feature, which uses an array of cameras, sensors, and radar to let the car take over the driving in highway traffic. In the driver's seat was Björn Giesler, Ph.D., project leader for development of piloted driving at  Audi  AG, and in the backseat was an engineer equipped with a laptop and radio to monitor the system and communicate with our police escorts and other  Audi vehicles.

    During rush-hour traffic, we headed out on Route 15, one of Las Vegas' major freeways. With the vehicle's speed under 40 mph, a notification appeared that the system's pilot mode was available. Then with the push of a button on the steering wheel, the car took control and the instrument cluster graphic changed to an illustration of the road with vehicles in the lanes.

    As Giesler took his hands off the wheel and his foot off the pedals, the vehicle seamlessly followed the car in front at a safe distance. When a vehicle cut into our lane, the  A7 automatically slowed down and adjusted the distance. When that car moved out of the lane, our car again closed the gap with the next car in front. The driver can turn off the system at any time by placing his hands on the steering wheel and foot back on the pedals.

    With the  A7 in control, the driver could do other things, although sleeping was not one of them. The vehicle was equipped with two cameras with facial recognition that monitored the driver's eyes. Giesler showed off that feature in an unnerving moment. "I don't want to lie to you, this is still pretty scary for me," he said as he pretended to sleep. After about 10 seconds the vehicle noticed. An audible alert sounded and, when he still didn't open his eyes, the vehicle shut down in the middle of the highway and activated the hazard lights. That is a safeguard on the prototype  A7 in case the driver is ill or incapacitated. But production cars will be designed so that they can make autonomous lane changes, which will allow the vehicle to safely pull off the road.

    During the demonstration, Giesler pointed out an eye-opening reminder of how quickly the technology is advancing. The previous year the test car's trunk was filled with three desktop-sized computers to make the system work. This year the hardware had been reduced to the size of a small box, which was tucked away in the trunk's side storage compartment.

    Overall we were quite impressed with the  Audi's capabilities. The company expects the technology to be available in a production car within five years.

    Roadblocks to autonomous cars

    Making connections
    Many of the building blocks for self-driving cars are already available.

    Over the coming years, the advanced safety features that are being developed will increasingly be linked into larger systems that will eventually allow cars to drive themselves. The benefits in terms of safety and convenience could be significant. Autonomous vehicles could help reduce crashes caused by human error, ease congestion, extend the driving years of the aging boomer population, and allow those who are visually or physically impaired to have greater mobility. But are we ready for them?

    "It's all about the T word—trust," says John Hanson, Toyota's national manager, advanced technology and business communications. "There has to be a level of trust that you have that the vehicle is going to perform the way you think it's going to perform."

    "Getting a car that can operate with the reliability that today's cars do is a staggering challenge," says Bryant Walker Smith, fellow at the center for automotive research at Stamford University. Even if autonomous cars save countless lives, "one headline, ‘Machine Kills a Child,' trumps 30,000 obituaries," he adds.

    "People shouldn't think that there will never be an accident," says Ron Medford, Google's director of safety for self-driving cars. Autonomous cars will be  "much, much better than a human," he says, but they won't be perfect.

    Volvo is planning a test of 100 autonomous cars on public roads in 2017. Nissan has said it will have an autonomous vehicle in production by 2020. But pinning down a firm date can be difficult. Some automakers such as Mercedes-Benz and Toyota say they can't give firm dates until the crash-avoidance technologies that are the building blocks of the cars are accepted and trusted, and that they prove they can reduce accidents.

    Even then, approval of autonomous vehicles may be challenging in our legal and regulatory climate. One critical issue: Who is ultimately responsible for the driving, the driver or the vehicle? The answer will be developed over time, as will the impact on insurance liability, and it may depend on the situation. An initial concern is how to pass control back and forth between human and machine, and what is the appropriate timing of that transition. Audi says 10 seconds is reasonable, based on its testing, and it will need to guarantee that a driver won't have to take control in an emergency.

    Despite the challenges, using leading-edge technology to replace our current system that  "consists of old, poorly maintained vehicles operated by poorly trained, easily distracted, unsupervised individuals has a lot of potential for safety gains," Smith says.

    We asked our Facebook followers what they think about the possibility of cars driving themselves. We received dozens of responses and a wide range of opinions at facebook.com/consumerreports, including these:

    Chuck: "The end of distracted driving and DUI."

    Emily: "I question an automated vehicle's ability to make safety judgments."

    James: "I do NOT want a car that drives itself. I don't even like cars that shift themselves! I still ENJOY driving and improving my skills."

    "Would love one for my husband, who is blind. This represents a lot of independence for the visually impaired."

    William: "Given that so many people have everything but driving to do while behind the steering wheel, it's great that at least something will be doing the driving."

    2014 Autos Spotlight

    Visit our Autos Spotlight special section to find all of our new and updated articles, plus see the latest Best & worst new cars, Best & worst used cars, Used car reliability, and New car Ratings & road tests.

    From 2014: Top Picks, Who makes the best cars, and Extended warranties.

    Editor's Note:

    This article also appears in the April 2014 issue of Consumer Reports magazine.

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