OAKLAND -- Public transit agencies can do little to prevent the kind of violent crime that happened on a BART train Saturday night when a gunman killed a passenger and escaped.
The killer and his victim remain unidentified early Tuesday, but the slaying at the West Oakland station had rippled through the BART rider community Monday.
"You've just got to take a chance on the people you see on BART," said an Oakland man who rides the train to his job at a noodle restaurant in San Francisco.
The man's comment reflects what experts say about public safety on mass transit: The fact that people riding the system are largely strangers makes crime easier, and safety is a matter of perception.
And, the experts seem to agree that there's not much a public transit agency can do to prevent a lone attacker such as the killer on the Saturday night BART train.
The gunman apparently waited until just before the train stopped at West Oakland, shot a seated passenger and ran out as the doors opened.
Witnesses to Saturday's attack had only a sketchy description of the assailant. Most threw themselves to the floor when they heard the gunfire, and BART released no information on whether the attack was captured on a train car video camera.
The best that can be done, studies say, is employ good surveillance equipment, and personnel and station design that limit opportunities for attacks.
"It is the same issue as in all public places," said Tom Radulovich, president of the BART board of directors.
New York City does random bag checks, but "nobody knows how effective that is," Radulovich said, adding that trying to screen BART's huge volume of riders "would really change the way we do business."
Riders on Monday had various reactions, but all said they were on higher alert.
"I ain't really safe in Oakland period, but I watch my surroundings," said Josh Heard, who boarded at San Leandro's Bay Fair station Monday morning.
"I would say ultimately I still feel it's safe overall," said Donald Munson, of Oakland.
The public's elevation of fear is a concern for transit agencies.
Even if the chances of violence are very low, Radulovich said, "the chances that it might happen is going to be in everybody's head."
Rod Diridon Sr., emeritus executive director of the Mineta Transportation Institute, said one of the better actions would be to put more trained security officers in stations where they can watch over and reassure passengers and deter crime.
But that would be costly and BART, like other public transit agencies, has for years been struggling with less financial support from the federal government, he said.
Diridon said major transit systems are installing "multiple levels of security," the details of which he couldn't discuss "but obviously they didn't work in this case."
"An individual attack is very hard to stop," he said.
The many studies of transit safety since the 9/11 attacks have a common thread. Researchers say it is impossible to fully protect transit systems that depend on concentrating large numbers of riders where the need for quick access prevents blanket security.
For instance, metal detectors that might deter riders with guns aren't economically or practically feasible in a system with so many gates -- BART has 46 stations and needs to move more than 400,000 people a day quickly to and from trains and stations.
The kind of security needed to detect an individual threat, Diridon and others say, would defeat the purpose of public transit.
"If you begin applying security like on airlines, transit would shut down," he said. "You can't have people walking through security checks that take time and block the flow."
Staff writer George Kelly contributed to this story. Contact Andrew McGall at 925-945-4703. Follow him at twitter.com/AndrewMcGall.