Technology: As Workload Overwhelms, Cars Are Set to Intervene

The simple act of turning left on Allaire Road in Wall Township, for example, is confounded by a traffic circle, where an attempt to head east casts the driver into a ballet of choosing the proper lane, looking for the exit and maintaining a high alert in the crush of beach-seeking vehicles.

Now imagine that during this encounter a low-tire warning flashes on the dashboard. Next, a chime alerts the driver that a text message — maybe important — has landed. Then the cellphone rings.

The overload of inputs, perhaps amplified by foul weather or a demanding toddler, presents a real challenge to the driver — and a danger to all road users. The National Highway Traffic Safety Administration estimates that distraction and inattention contribute to 20 to 30 percent of reported crashes.

Much as regulators and automakers have rushed to deal with the flood of distractions that invade the automobile — GPS displays, Internet radio, e-mail and even Facebook apps — there is a growing effort by engineers to build cars that gauge the difficulty of situations and recognize a driver in distress. Then the car would react, delaying all but the most urgent alerts, sending phone calls to voicemail and freeing the driver to focus on the task.

The study of driver workload management — some would point to the irony in this reaction to a situation partly created by automakers themselves — is progressing alongside the efforts of the planners who dream up new generations of infotainment features. A foundation of workload study is the Yerkes-Dodson Law, a theory developed in the early 20th century that plots workload and performance on a bell curve.

There can be trouble at either end — an inattentive, underworked driver may be as much a risk as an overworked driver who cannot handle the combined sensory inputs and driving chores. In the middle is the ideal, a driver functioning at optimum level.

Systems that detect driver drowsiness, like the Mercedes-Benz Attention Assist feature, can prompt a driver to be more alert, but driver overload is harder to manage. N.H.T.S.A. has issued voluntary accessory-design guidelines in an effort to reduce distraction, but given consumers’ hunger for gadgets, managing those distractions to reduce workload may prove a better solution.

As safety groups press for restrictions on phone conversations and messaging in the car, the urgency to find a solution will only increase, experts say. Studies of driver workload have a long history, but a milestone came in 2003 when the John A. Volpe National Transportation Systems Center, a unit of the Transportation Department — in conjunction with Delphi, the giant parts supplier, Ford Motor and several universities — began a research project to quantify distractions and driving situations as a way to generate workload estimates.

Paul A. Green, a University of Michigan research professor, said in a telephone interview that the Volpe study stimulated research. Today, automakers and universities are developing technologies that will let them measure the level of driver stress and the response to the pressure. That data could be used by a management system that would delay calls, alerts, text messages and warning lights at the times when the driver’s workload was peaking and the stress level was high.

Because many cars are equipped with advanced electronics — radar, sensors and cameras developed to enable features like smart cruise control and lane-departure warning — some of the equipment needed to gauge workload is already in vehicles. Sensors that determine speed, throttle position, steering wheel angle and transmission gear selection, and even weather conditions, can be adapted to see traffic on the road and monitor driving situations.