FORT LAUDERDALE, Fla. — Seniors often choose not to drive on the interstate, convinced they'll be safer out of high-speed traffic. But a new study shows the intersections they'll travel through on city streets are more dangerous.

Intersections are where 40 percent of the fatal collisions involving drivers age 70 and older and other vehicles happen, according to a report released Monday by the Insurance Institute for Highway Safety. That rate compared to 23 percent of fatal crashes involving those 35 to 54 years old, researchers found.

The new data gathered by the institute on 200 Connecticut intersection crashes found 58 percent of drivers age 80 and older had intersection crashes due to their failure to yield. The most common reason among youngest drivers was rear-ending another car.

Anne McCartt, the institute's senior vice president for research, said the results suggest age-related vision and depth-perception issues contribute to senior's problems at a crossroads, while younger drivers are impatient and distracted. Older adults also have less range of head movement and a lower ability to process multiple information cues simultaneously, making a four-way intersection's cacophony of signs and lights particularly confusing.

The report's suggestions for what might help: better designed intersections with green arrows controlling left turns and more traffic circles instead of signaled intersections. Circles tend to slow vehicles and funnel traffic in a single direction.

Seniors could be safer if they take to the highways, McCartt said — but not if they are uncomfortable with interstate congestion and high speeds. Instead, she advises older drivers to be aware of intersection dangers, approach cautiously and take their time.

That's the same advice Allen Kaplan, of Tamarac, Fla., gives students in his 55 Alive classes, defensive driving sessions sponsored by AARP. "I tell them please, do not make a left turn until you are sure there is no danger," said Kaplan, 75, a retired university professor. "If someone behind you is blowing their horn, ignore them."

South Florida, where sprawling, rapid growth has challenged roadways to keep up, is home to plenty of heavy city street traffic. A 2001 survey by State Farm looking at insurance claims and accident severity by location claimed the nation's most dangerous intersection was at Pines Boulevard and Flamingo Road in Pembroke Pines, home to an estimated 357 accidents in two years.

While some disputed State Farm's methodology, Kaplan agrees South Florida's roads are challenging. "I am scared silly when I go into an intersection," he said. "People don't stop, don't look, don't care."