Eve R. Meyer, executive director of San Francisco Suicide Prevention, said the popular argument was based on ignorance. “Scientific evidence says a barrier reduces suicides, because thoughts of suicide are transient,” she said. For years, she said, when she raised the issue of a barrier before the board, she was shunned.

Dr. Mel Blaustein, medical director of psychiatry at St. Francis Memorial Hospital in San Francisco and an early proponent of a barrier, said, “Young people think the bridge is a perfect place to go.”

People see jumping off the bridge as an easy way to die, he said. “There is a misconception that it’s painless.”

Those who jump plummet 220 feet and typically suffer rib collapse on impact, lacerating lungs and other internal organs, said Ken Holmes, the retired Marin County coroner who saw so many bodies of bridge suicides that he became a major crusader for a barrier. He said they die of internal bleeding or drowning.

Dr. Blaustein said, “The most common myth to explode is that people will go elsewhere.”

In a 1978 study, “Where Are They Now?” Richard H. Seiden, a former professor at the University of California, Berkeley, School of Public Health, looked at the question of whether someone prevented from committing suicide in one place would go somewhere else. He studied people who attempted suicide off the Golden Gate Bridge from 1937 to 1971 and found that more than 90 percent were still alive in 1978 or had died of natural causes.

Mr. Mulligan believes that the board “has become more informed” and that the stories parents tell about the loss of their children have made a difference.