Texting Can Double A Driver’s Reaction Time
October 6, 2011

Texting Can Double A Driver’s Reaction Time

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The Texas Transportation Institute (TTI) has determined that a driver´s reaction time is doubled when distracted by reading or sending a text message, according to results from a new study published Wednesday.

The study reveals how texting impairment is even greater than many experts previously believed, and also demonstrates how texting drivers are less able to react to sudden hazards.

“Essentially texting while driving doubles a driver's reaction time,” Christine Yager, who led the study at Texas A&M University´s Texas Transportation Institute, told Reuters. “That makes a driver less able to respond to sudden roadway dangers.”

The study, the first published work in the US on the dangers of texting while driving in an actual environment, consisted of three phases. In the first phase, participants were asked to type a simple story of their choice and then read and answer questions related to another story, both on their smartphone in a lab setting.

In the second phase, each participant navigated a test-track course involving both an open section and a section lined by construction barrels. Drivers first drove the course without texting, then repeated both lab tasks while driving through the course again. Through the course, a periodic flashing light recorded a participant´s reaction time.

The fact that the study was conducted in an actual driving environment is important, the researchers said. While simulators are useful, the dynamics of an actual vehicle are different, and some driver cues can´t be replicated in a simulator. By using a closed course, researchers can create an environment similar to real-world driving conditions while providing a high degree of safety for the participants.

The study consisted of 42 drivers between the ages of 16 and 54. The typical time it took a driver who was not texting to respond to the flashing light was one to two seconds. When texting while driving, however, reaction time extended to three to four seconds, and the texting driver was 11 times more likely to miss the flashing light altogether.

To put the findings in context, Yager said drivers going 30 mph travel 220 feet in five seconds. “If you´re on a freeway where the speed limit is 60 in rush hour and a vehicle suddenly stops in front of you, that´s not enough time to react if your eyes are glanced down at your phone,” said Yager.

“The act of reading and writing a text message are equally impairing and equally dangerous,” said Yager.

The 3-4 second lag time in the study is significant, said Yager, because in that period at highway speeds one can travel the length of a football field.

“Our findings suggest that response times are even slower than what we originally thought,” she said. She added that the new research differed from previous studies in that it involved participants driving actual vehicles, not simulators.

Also, the research community considers 40 drivers to be acceptable to produce meaningful findings in this type of study; previous research used as few as 20 drivers.

In addition to the reaction-time element, researchers also measured each driver´s ability to maintain proper lane position and constant speed. They found that drivers who were texting or reading messages were less able to safely maintain their lane position, swerving worse in the open sections of the course than in the barreled sections. They were also unable to maintain a constant speed while texting, tending to slow down in the process. By slowing down, a driver gains more time to correct for driving errors.

“Even though we had participants drive at 30 miles an hour with very wide lanes on the test track, we still had many close calls,” Yager noted. “We had participants strike barrels, and it is very scary to think that this is happening on our public roadways.”

Texting and driving has already been deemed dangerous, with 34 states enacting bans on texting while driving, according to the Governors Highway Safety Association. Texas approved a texting ban earlier this year, but Governor Rick Perry vetoed the measure, calling it an “overreach” and a “government effort to micromanage the behavior of adults.” Although, the state does ban cellphone use in school zones and includes restriction to drivers under age 18.

The US Transportation Department says distracted driving accounts for as much as 20 percent of all fatal crashes, and that cell phones are the primary source of driver distractions. In 2009, nearly 5,500 people died and half a million were injured in crashes involving a distracted driver, according to statistics from the National Highway Traffic Safety Administration (NHTSA).

Jonathan Adkins, a spokesman for the Governors Highway Safety Association, said the study reinforces the group´s push to get texting bans adopting all across the country. “Texting while driving is dangerous and drivers really don´t have any business texting while driving, no text is that important,” said Adkins.

The TTI study “gives more and more credibility to the fact that texting while driving is dangerous,” he added. “Maybe it´ll have some impact in Texas as well, maybe it´s the tipping point. We can hope at least.”

Researchers pointed to two numbers to illustrate the magnitude of the texting while driving problem: an estimated 5 billion text messages are sent each day in the United States, and at least 20 percent of all drivers have admitted to texting while driving.


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