Why do people drive into flooded washes? - Tucson News Now

Why do people drive into flooded washes?

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Source: University of Arizona Source: University of Arizona

Ashley Coles' Master's thesis research question was "Why do people drive into flooded washes?".  With an interest in flood risk, I naturally picked up on her research.  This week the below news release came out from the University of Arizona.  Her research was already highlighted in the KOLD News 13 Monsoon 2010 special, which is the video accompanying this story. - Erin

TUCSON, AZ (UNIVERSITY OF ARIZONA) -Many of us have been there: Do I risk crossing this flooded roadway in my seemingly sprightly family sedan? That guy in front of me just made it.

But what are the psychological reasons why certain people take the chance at crossing, risking personal injury, vehicular damage or death? Ashley R. Coles conducted an investigation to find out.

It turns out that, for most people, it comes down to a calculated negotiation.

Coles, a University of Arizona doctoral student studying geography, surveyed more than 170 people in Tucson as part of her study, "Driving into Danger: Perception and Communication of Flash Flood Risk from a Cultural Perspective."

"It seems like an obvious thing you wouldn't do, so why do so many people do it? The assumption is that people have a misconception about the risk," said Coles, who has presented her research several times, once earning the Young Scientists Outstanding Poster Presentation award at the 2009 European Geosciences Union conference.

Coles is working to publish her results with Stephanie  Fryberg, a UA psychology professor, and her thesis adviser,  Katherine K. Hirschboeck, an associate professor of climatology who also has an appointment in the School of Geography and Development. Her work was funded by Climate Assessment for the Southwest.

Coles said the conundrum is that people will choose to cross despite ample warnings in public service announcements, news accounts and signage warning against driving through flooded roadways and washes.

In fact, the behavior of some motorists resulted in what is commonly termed the Stupid Motorist Law in Arizona. Individuals who must be rescued from floodwaters after having crossed a barricade are financially liable for some emergency response expenses. 

"The Stupid Motorist Law, which is designed to be a deterrent, is not the major deterrent at all," Coles said, adding that some also will cross despite the risk of injury or death.

The U.S. Natural Hazard Statistics reported in 2009 that 53 people died in flash and river floods with 57 percent of them having been caught in a vehicle. The agency also reported that, overall and consistently, nearly half of all flash-flood deaths involve a vehicle.

Coles also found that people tend to have a high level of trust in signage and barricades at flooded roadways.

"About 90 percent agree that the signs indicate the possibility of a flood occurring in that location," Coles said, adding however that "the signs do not reveal whether the situation is currently dangerous."

And she found some interesting variation when she considered a range of social and cultural factors such as individual trust, self-efficacy and perceptions about time.

"Cultural factors influence perceptions, which then influence behaviors," Coles said. "That behavior is going to become information for other people, and for yourself." 

Coles said signage and expert messages were not the only sources of information, but that people tended to rely on a range of sources to make a decision about whether or not to cross.

People said they tended to cross if it appeared that weather conditions were getting worse, if they could not find another route and if they saw that vehicles had successfully crossed.

Those who chose not to cross did so because they had children or other family members in the vehicle, they felt it was too dangerous or were worried that crossing might damage their vehicle. 

"It's not that people don't trust the signs or the information, it's just that the signs are ambiguous," she said. "So people feel they have to use some other information to decide whether it is dangerous or not right now." 

Coles noted that 78 percent of respondents said they relied on the advice of family, friends, neighbors and others about whether to cross, sometimes even making the call at the flooded roadway or wash to inquire. 

"People are making the decision to cross based on a huge assortment of information, not just a sign," she said. 

Yet Coles found that flood risk managers and others often believe that individuals who choose to cross are being irrational, overconfident, "stupid" drivers. 

"A lot of my findings contradict some of the major thinking of people, especially that they are being impulsive or that they don't know any better or that they are overconfident," Coles said.

"The main reason why this is important is because it challenges the belief that people drive through because they are being irrational," she said. 

Consequently, greater lessons must be learned.

Of note, Coles said the use of roadways as channels for floodwaters can be a risky practice.

"We have hundreds of low-water crossings in town," she said. "The flood risk managers are saying, 'Why are people driving through flooded streets?' and people are asking, ‘Why is there water in our streets? This is where we drive.'"

But the real problem, she said, is "that the best approach is not to drive at all when it is raining." Family or other responsibilities can make the decision not to drive a difficult one, she also noted.

"Education is important but limited in its ability to prevent risk-taking behavior," Coles said. 

"As shown by this research, people already know that they should not drive through flooded streets," she added. "What has not been considered is the possibility that the decision to do so is not always irrational."

In addition to drivers, flood risk managers also have much to learn, she said. "Understanding how culture influences risk perception and behavior is critical for effective risk management and communication."

(Copyright 2010 by the University of Arizona. All Rights Reserved.)

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