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Traffic Roundabouts : Caltrans Plans to Go in Circles

August 27, 1988|JESSE KATZ | Times Staff Writer

In a scene from the movie "National Lampoon's European Vacation," Chevy Chase gets a laugh when he finds himself trapped in a British traffic circle, whirling frantically, unable to exit, for hours.

But here in California, the state Department of Transportation is not amused.

The agency hopes the state's roads will someday be dotted with the doughnut-shaped intersections, called roundabouts, which, by eliminating stoplights and head-on traffic, have been credited with saving lives and easing gridlock throughout the United Kingdom.

Minimizing the possibility of head-on and broadside collisions, roundabouts have been credited with reducing accidents by 40% to 60%, and fatal accidents by as much as 85%, according to several studies in Britain and Australia.

Search Launched

Convinced that the roundabout can do the same for California's congested streets, Caltrans has launched a search in Los Angeles and Ventura counties for an intersection of two state highways to serve as a test site.

If constructed, the British-style circle--which differs from most existing American rotary intersections by assigning right-of-way to cars already traveling around the center island--would be the first of its kind in California.

"This is a great chance to do a service for humanity," said Al Maas, a senior Caltrans engineer who retired in July from the agency. "We have an obligation to try this thing out."

So far, that has not been an easy task. Caltrans spent the last two years trying to convince Ojai residents that the two state roads intersecting in the small Ventura County community would be an ideal spot to showcase the device.

Many of the town's 7,850 residents, however, balked, fearing that they would be guinea pigs in an experiment doomed to end in confusion, if not tragedy.

Shunned by Professionals

Skepticism is also shared by many of the nation's traffic professionals, who long ago shunned rotaries, such as those found in Long Beach, Bakersfield and spots throughout the East, for their tendency to bog down during peak hours.

Some worry, too, that timid drivers may panic, a la Chevy Chase, and get trapped by more aggressive motorists whizzing around the circle.

"To many people, it's a very uncomfortable experience," said Ernie Flores, senior traffic engineer for Long Beach, where a rotary marks the intersection of California 1 and California 19. "Although traffic circles may look pretty, they're really not that functional."

Caltrans hopes to prove them all wrong. While the British roundabout doesn't look much different from America's older, chaotic rotaries, which flourished in the 1920s and '30s, advocates say it keeps traffic flowing far more smoothly.

"The thing is to get the first one built," said Leif Ourston, a Santa Barbara engineer who was Caltrans' consultant on the Ojai proposal. "Once they catch on, you'll see people demanding them and cities requiring them."

Those benefits stem primarily from the British right-of-way rule, which calls for approaching motorists to yield until there is a gap in the circulating traffic, Ourston says. In most U.S. rotaries, entering motorists do not have to yield and often bring traffic screeching to a halt when they merge into the circle.

In addition, the roads feeding a roundabout intersect the circle at a nearly perpendicular angle, forcing motorists to slow down and yield to circulating traffic. By contrast, most American rotaries are designed so that motorists hit the circle at a less steep angle, allowing them to maintain their speed and cut off cars traveling around the island.

Finally, the feeder roads to a roundabout flare out to three or four lanes just before they meet the circle, permitting several cars to enter simultaneously at peak traffic hours.

Battling Inertia

"Those improvements mean the difference between a smooth-running pleasant situation and a white-knuckle situation," Ourston said. "The subtleties really matter."

While some U.S. traffic circles employ some of the same design features as roundabouts, none are exact copies of the British model and do not perform as well, Ourston said.

Some, for example, have no yield stripes on the highway, he said. Other minor deviations, such as pedestrian crossing islands and parking along the perimeter of the circle, add to confusion and hinder the smooth flow of traffic.

"What Caltrans is doing is absolutely unique," Ourston said. "We're trying to bring the state of the art and demonstrate it here in America."

But many traffic engineers, even if they accept the merits of the improved British version, say they are reluctant to experiment with such unfamiliar concepts, especially in today's litigious society.

Others point out that American drivers have grown accustomed to traffic signals and stop signs, tools that regiment the flow of cars and reduce the need for individual judgments on the roadways.

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