How Traffic Jam Assistance Systems Work

Trust the Car, Not Your Instincts
Radar sensors and a camera give input to the system, which automatically controls the speed, the brakes and the steering in order to follow the vehicle in front.
Radar sensors and a camera give input to the system, which automatically controls the speed, the brakes and the steering in order to follow the vehicle in front.
Courtesy of Volvo Car Group

Volvo, eager to determine if the traffic jam assistance system had more widespread potential, ran a few tests to see if it actually could alleviate traffic jams.

The SARTRE (Safe Road Trains for the Environment) project sounds like it was researching the safety of the super-long semitrailer trucks that are known as "road trains" in some areas (namely Australia). But in Volvo-speak, a road train is a pre-coordinated stream of cars that use advanced cruise control-type technologies to follow each other in a planned path of travel, with established safe following distances between each vehicle. A touch screen lets the driver input commands, such as joining or exiting the road train, or communicating with other vehicles in the road train, but beyond that, the driver of each individual car in the road train is largely relieved of the burden of driving.

The technology used in the SARTRE program, similar to the suite of tools that makes up traffic jam assist, was already in the cars used for the test -- it was composed of other safety features that have (in comparison) stood the test of time, like adaptive cruise control, blind spot monitoring and park assist. Since the cars' onboard diagnostics are so sensitive and precise, Volvo says that, at times, the road train traveled safely with less than 13 feet (3.9 meters) from bumper to bumper.

Volvo sees this technology as a plausible alternative to public transportation, providing a combination of an individual's own comfort with automated travel. It also offers moderate energy savings over regular driving, and takes up less space on the road than the same number of vehicles would occupy if each were driving independently. However, it's not as simple as just joining a line of cars that happens to be heading in the same direction. The road train must be scheduled and coordinated ahead of time, and led by a professional driver. There are too many questions that need to be answered, such as how well a road train can cope with an unforeseen road disaster. And, so far, all of Volvo's tests have been focused on potential for the European market -- whether or not this will fly in the United States is completely unknown.

There are reasons other than the home-court advantage that convinced Volvo to test in Europe. From an automaker's perspective, the United States' safety regulations are an absolute mess [source: Lavrinc]. In addition to the nationwide federal regulations, a handful of states have their own standards and restrictions that go above and beyond the national benchmark, which must be met for every car sold within that state. It's really difficult for automakers to develop new technology when these standards are constantly changing. Sometimes, it's nearly impossible for a new innovation to meet the most restrictive demands of a specific market -- even if it passes muster almost anywhere else. Europe, however, is a lot easier for a European carmaker to navigate. In other words, Volvo needed to ensure its tools worked as intended before custom-calibrating them became part of the plan.

If this seems like it's going somewhere else, it is. Volvo's ultimate objective is autonomous driving -- a car that can move with minimal input from the driver. The automaker says studies show that about half of all drivers would be comfortable in a self-driving car and part of the push for autonomous driving technology comes from an increase in potential distractions -- namely, texting [source: Volvo]. Widespread use of this technology could potentially cut down on accidents. Volvo is quick to point out that this shouldn't be a substitute for the driver's judgment -- any input from the driver's controls will override the automatic motions. (That's assuming, of course, that the driver is still awake.)

The progress that's been made in just the last few years eclipses the previous several decades, and at times, it seems like automakers are closer to their goals than they let on. But it's important to note that it's all happening gradually, at a controlled and deliberate pace. It helps everyone -- consumers and government safety regulators -- adjust to the changes slowly, so they don't become overwhelming or dangerous, which would threaten long-term acceptance and future development. If we went from something as simple as cruise control to fully-self-driving cars, without a steady flurry of new tech rollouts in between, people would probably be terrified and unwilling to give it a try. But by the time traffic jam assistance rolls out in 2014, consumers should be pretty well prepared.

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