Is cruise control dangerous?

One study says yes. Using cruise control on a highway may make your road trip more enjoyable, but it could also reduce your reaction time and hamper your ability to change lanes safely.

Josh Armstrong/The Christian Science Monitor/File
The 2005 Toyota Avalon, like many other cars, offers drivers the option of using cruise control. Is it safer not to use it?

For decades, cruise control has been a common feature on automobiles. It's beloved by many road-trippers, who say that it reduces fatigue and boosts fuel economy.

But others aren't so sold on the technology. When it debuted, for example, older drivers worried about their ability to deactivate it. That's not much of a concern nowadays, but a new study from the VINCI Autoroutes Foundation suggests that cruise control poses other dangers. 

The study employed 90 subjects, who were put into a driving simulator and challenged with four different scenarios: approaching a toll booth, encountering an 18-wheeler accident in the passing lane, encountering construction in the driving lane, and entering an area in which their speed was tracked by radar. 

Subjects went through each scenario three times -- once using cruise control (which sets a car's minimum speed), once using a speed-limiter (which sets a car's maximum speed and is uncommon in the U.S.), and once using neither device.

Researchers identified a number of problems among those using cruise control and speed-limiters:

  • Drivers frequently engaged in unsafe behavior when overtaking other vehicles. Those using cruise control stayed in the passing lane longer because they had difficulty modulating speed. In fact, they often remained in the passing lane long after they'd overtaken a vehicle. 
    • When cruise control-users did move back into the slow lane, they tended to do so without leaving a safe distance between their vehicle and the one they'd just passed. Moreover, cruise control caused those motorists to slow down once they'd settled into the driving lane, cutting distances even more.
    • Drivers in cruise control scenarios didn't correct their direction as often as other test subjects, meaning that they had a greater chance of slipping into another lane or drifting off the road entirely.
    • Reaction times of those using cruise control were slowed by an average of one second. At a speed of 70 mph, that one second translates to a stopping difference of over 100 feet.

    Researchers attribute some of these problems to a lack of attentiveness on the part of cruise control users. Though many proponents of the technology claim that it reduces driver fatigue, the motorist's lack of engagement when using cruise control could cause the opposite to be true.

    The Foundation's Bernadette Moreau notes that the study isn't meant to do away with cruise control altogether, but to make motorists aware of when it should -- and shouldn't -- be employed: "The idea is not to simply advise drivers to refrain from using these driving aids, which provide real benefits in terms of speed limit compliance and comfort.... However, these aids should not be used systematically, but rather advisedly, and a number of precautions should be taken."

    You can check out a summary PDF of the report here. Complete results should be released later this fall.

    [BBC via Marty Padgett]

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