A truck plunges into a flooded wash on Snyder Rd. just west of Soldier Trail despite signs warning that the road is closed following rains that left portions of northeastern Tucson flooded Mon., Jan. 28, 2008. KELLY PRESNELL/Arizona Daily Star 2008

The monsoon always brings a flood of stories about "stupid motorists" who drive through flowing washes - but the really stupid practice is paving dips and washes and calling them streets, says a UA researcher.

Most motorists who drive through washes have very rational reasons for doing so, said University of Arizona researcher Ashley Coles.

"The irrational ones are the ones who designed the streets," said Coles, a Ph.D. candidate in geography who conducted a survey of monsoon driving habits for her master's thesis and is finishing a scientific paper on the results.

In a survey of 160 Pima County residents, 61 percent admitted to driving through a flooded wash, despite knowing the dangers and despite being aware of the "stupid motorist" law that provides heavy fines for disregarding a barrier.

To be clear: Coles does not advocate the practice of driving through flooded washes. She notes that half the 100 flood fatalities in the nation each year involve vehicles.

She has discovered, however, that making the decision to drive through a wash is not necessarily stupid.

Most motorists who responded to her mailed survey said they know that driving into flooded washes is dangerous, with 80 percent saying they trust signs that say, "Do not enter when flooded" and 90 percent saying they trust temporary barricades.

The signs, though, are just one piece of information among many used to make the decision to drive through or not, Coles said.

Other factors include familiarity with the road, existence of a convenient alternative and timetable.

The clincher, though, is seeing another motorist make it through safely.

"They said they'll watch other cars go through and compare - 'That car's smaller than mine.' "

Such calculations can be deadly, said Ken Drozd of the National Weather Service Office in Tucson.

Conditions change quickly in a flowing wash and the size of your vehicle doesn't necessarily mean you are better able to go through, he said. You also might drive in a slightly different spot that has been undermined by the rushing water.

Drozd organizes the annual Monsoon Safety program that includes the Weather Service's "Turn Around, Don't Drown" warning.

Coles said the community has done a good job of publicizing the danger and her survey found that motorists are aware of it.

She also doesn't fault contemporary road engineers for the historical problem of paved washes.

Current engineering standards require all-weather crossings - either culverts or bridges - over washes, said Andy McGovern, transportation administrator for the city of Tucson.

It's been that way for 30 years, he said.

The city has 150 to 200 street dips, McGovern said, each of which would cost a half million dollars to fix.

That would add up to $75 million to $100 million, he said - and that's just not happening with the road money currently available.

It's a lot cheaper to activate "Operation Splash" 8-10 times a year, putting up barricades that have been conveniently stashed at known trouble spots.

In addition to the dips, many city streets were designed to carry water, though the city has added storm sewers to its major arteries over time. "There is no more of this using Alvernon or Speedway to convey water," McGovern said.

The dips and the washes that serve as streets are remnants of a simpler time in Tucson, when it wasn't a metropolitan area of nearly a million people. It didn't rain that much and people just tended to wait things out.

When it rains, we would be smart to take a lesson from those Tucsonans who came before us, said Karen Rahn, transportation program coordinator for Pima County.

"If it's really flooded," she said, "pull into a restaurant, get a cup of coffee, call home and say, 'I'm going to wait until the water goes down.'"

Contact reporter Tom Beal at tbeal@azstarnet.com or 573-4158