The lead author of a recent study on suicidal and accidental deaths on Caltrain tracks identifying time and location patterns, Jan Botha, hopes the study’s results can be applied to other commuter rail quarters around the country.

The study comes as a prerequisite to determining the causes of some railroad suicides. Botha, a transportation engineering professor at San Jose State University, used data from August 1992 to December 2009 in an effort to ensure that the sample was large enough to be statistically significant and also to account for inevitable changes in the train system and surrounding environment over time.

“The reason why we picked such a long period is because if you divide the number of years into the number of deaths, they are still very rare events,” Botha said, adding, “Our results wouldn’t be too meaningful if we did it over a period [of] 10 years, because things change, like the roads, traffic flow and population. All of that changes.”

Botha’s research is part of a larger study conducted by the Mineta Transportation Institute, according to Mineta executive director Rod Diridon. It will contribute to the first phase of the Mineta study, which focuses on the causes of these incidents.

“We’ll be doing a whole panel of additional studies leading to a study that will recommend remedial action, not only for Caltrain, but other systems around the nation,” Diridon said. “We’ll look at the issue from every perspective imaginable, from physical structures, barriers, warning signals, lights, signs, and all the way to psychological issues.”

While the study cannot evaluate the success of current suicide prevention methods, it recommends that “Caltrain continue to monitor suicides to detect patterns and attempt to mitigate the circumstances where the suicides could be prevented, if such prevention methods would be feasible from economic and other viewpoints.”

Botha said that while the study provides analysis of the historical range of Caltrain deaths, it cannot provide explanations of the causes for suicides.

“At no point did we attempt to speculate or make conclusions about the cause of the suicide, because we are not experts in that,” Botha said. “We only made conclusions about the patterns, what we can see.”

Results show that the peak periods of suicides correlate with high-operating periods on the train and that they tend to cluster at the beginning of the month. While researchers couldn’t find a distinctive trend for the month or year that the deaths occurred, the study determined that most occur on weekdays, especially Mondays and Fridays.

Botha’s team, which consists of two graduate students from San Jose State, also found that some deaths tend to occur more frequently in certain areas over others.

“Very few deaths were close to San Francisco because the system is in a tunnel there,” Botha said. “There was a uniform suicide frequency in the area north of San Jose, simply because it’s older and denser. But if you look at what happens south of San Jose, there are very few suicides and deaths because of the smaller population.”

Suicides were concentrated at the 25-mile distance between Burlingame and Sunnyvale stations, while only one suicide occurred south of San Jose. This could be explained by these areas’ older neighborhoods, which suggests a stronger integration of the railroad with the community in these areas.

Additionally, both suicides and unintended deaths tended to occur farther away from stations. Twenty percent of the total suicides occurred at Caltrain stations and two-thirds of the suicides occurred within one half of a mile from stations. On the other hand, a larger number of suicides occurred near a road crossing, as 43 percent occurred within one tenth of a mile away and almost two-thirds occurred within three tenths of a mile.

Not all Caltrain deaths can be categorized as “suicides.”

“Suicides are relatively uniform pattern, whereas the unintended deaths have spikes, which means that there may be ongoing problems,” Botha said. “This may be because there are more people crossing there, or there might be a site obstruction.”

In some cases of unintended deaths, these spikes were eliminated as improvements were made on the problems causing these accidents, Botha said.

But Botha’s study is only the beginning.

We have to find the causes first,” Diridon said. “I think [Botha] has done a good job of getting started in that direction.”

Caltrain spokeswoman Christine Dunn said prevention efforts remain a top priority, an endeavor that gained even more importance after the 19 incidents last year. New methods include more signs around stations that display a suicide hotline.

Moreover, Diridon emphasized that suicide is a community-based issue that is not limited to this particular case study.

“This issue is a concern all across the nation, not just here at Caltrain,” Diridon said. “In fact, we sometimes forget that Caltrain is one of the best-run train systems in the country, in terms of performance, passengers carried and other measures.”