Street criminals love unsupervised mass transit as it allows them access to a captive audience for theft and harassment.

Making mass transit safe involves following the example set by New York City and this article from City Journal gives a good look.

An excerpt.

At 10:20 PM on Sunday, September 2, 1990, 22-year-old Utah resident Brian Watkins, accompanied by his parents, brother, and sister-in-law, entered the New York City subway system in midtown Manhattan, intent on a short D-train trip uptown for dinner at Tavern on the Green in Central Park. They never got there. A group of teenagers surrounded Watkins and his family on the subway platform. They attacked Watkins’s parents, slashing his father’s pants open and hitting and kicking his mother. When Brian and his brother tried to defend them, the muggers plunged a knife into Brian’s chest, killing him. The murderers then fled to the nearby Roseland Ballroom, using money they had stolen from the Watkins family to buy tickets.

Watkins’s killing made national headlines. Time ran a cover story on “The Rotting of the Big Apple,” with its soon-to-be-famous image of the I ❤ NY logo with the heart split asunder. The event “summoned forth horror and soul-searching in a city that has already known too much of both,” People noted. Coming in the first year of David Dinkins’s mayoralty, the murder would help propel Rudolph Giuliani into the mayor’s office three years later, as Democratic voters turned to a Republican prosecutor to get a seemingly ungovernable city under control.

Yet Watkins’s death was not so unusual. His was the 18th killing in New York’s subways in 1990, and eight more would follow by the end of the year. The year before, underground assailants killed 20 people. Indeed, such violence was familiar already in 1981, when 14 lost their lives in the subways. Many considered these deaths an inevitable part of living in the big city. In 1985, for example, the New York Times blithely reported that the subways were safe enough, at least “for those who avoided the most dangerous stations, the ones with all the ramps and posts and connecting passageways in Midtown.”

By contrast, more than three decades later, New York really does have a safe subway system. Last year saw two subway murders, the same as the year before. Over the past 11 years, 26 people have been killed waiting for or riding on trains—matching the number killed just in 1990, the year of Watkins’s death. Today, few would worry that it might be unsafe to ride a train at 10:20 PM on the weekend. Trains at that time of night are packed with passengers.

Policing played a huge role in making Gotham’s subways safe, as it did in reducing crime throughout the city. In fact, the New York crime turnaround began in the subways, and what the police discovered about violence underground would prove essential to the broader battle for the city’s streets. The police could not have done it alone, though: in the decade before 1990, New York was already taking the first halting, yet critical, steps toward saving its subway system.

When I was eight years old, I used to ride the subway by myself,” recalls Ray Kelly, New York’s police commissioner under Dinkins and later again under Mayor Michael Bloomberg. That was just after World War II, when subway crime was negligible. Kelly remembers, too, the “feeling of danger and disorder” that set in during the early 1970s.

By then, the whole system seemed to be crumbling into ruin, as budget-crunched state and city officials slashed maintenance costs. In 1974, the state-run Metropolitan Transportation Authority, which operates the city subways, even stopped doing routine track inspections in an effort to save money—thus ensuring derailments, which began happening regularly. The trains were ever more decrepit, with 10 percent of the cars out of service every day, resulting in constant delays. “It was horrendous,” says David Gunn, who headed the subway system from 1984 to 1990. “The thing was a physical wreck,” he adds, with “each car breaking down every week.” In a recent speech to a Chicago audience, Tom Wright, president of New York’s Regional Plan Association, observed: “For folks who weren’t in New York back then, it’s hard to imagine today what the system was like. I was a kid in New York. Cars derailed on a daily basis, caught fire; you’d pull into the station and the doors wouldn’t open. Of course, everything was covered with graffiti.”

Violent crime began its seemingly inexorable rise. As late as the mid-1960s, subway murder was rare; during one stretch, only two people died over more than a year. In 1973, however, nine were killed. A year later, reacting to public alarm at higher violence, New York mayor Abe Beame decided to close the rear cars of subway trains, seeking to keep riders nearer to the conductor’s car, and presumably safer. Ceding space to robbers and killers proved an ineffective crime-fighting strategy, and the body count climbed. Most victims, like Watkins, were civilians, including Eric Kaminsky, a 22-year-old music student stabbed to death waiting for a train in Manhattan, and 32-year-old Jose Hugo Martinez, pushed to death from a platform in Queens. Transit workers and police lost their lives as well: in 1979, clerks Venezea Pendergast and Regina Reicherter burned to death when teens firebombed their Broad Channel (Queens) token booth; in separate incidents in 1980, transit cops Joseph Keegan and Seraphin Calabrese were murdered with their own guns at the busy Columbus Circle station when trying to apprehend lawbreakers.

By the time Bernhard Goetz made national headlines in 1984 for shooting four teenagers whom he claimed were menacing him on a Manhattan subway train, the public was on his side: a grand jury at first refused to indict him for attempted murder. Yet the growing outrage didn’t translate into safety gains. Gunn remembers another token-booth clerk killed when he was in charge—Mona Pierre, burned to death in 1988, in the third robbery attempt at her Bushwick station that year.

New Yorkers started shunning the subways. Between 1970 and 1980, annual ridership fell from nearly 1.3 billion trips to just over 1 billion, a percentage drop more than double the city’s 10 percent population loss. With no safe way to get around a dense city via public transportation, the New Yorkers who stayed began using their cars more, increasing congestion and pollution in a city getting harsher by the day. Richard Ravitch, who chaired the MTA from 1979 until 1983, recalls telling a reporter in 1980 that he wouldn’t let his 12-year-old son ride the trains at night; he came home to the preteen complaining, “You humiliated me.”

Even as subway violence intensified, the city and state had been putting conditions in place that would later prove crucial in the fight against crime. In 1984, Gunn and his boss, MTA chief Bob Kiley, made the decision to go after graffiti, which they saw as a symptom of the city’s disorder. For years, Mayor Ed Koch had urged transit bosses to clean graffiti from their trains. In 1981, the MTA had even deployed two guard dogs to scare potential taggers away from a train yard. New York also launched a public-service campaign, telling would-be train defacers to “make your mark in society, not on it.” The MTA repainted some train cars white, Gunn says, but “it was a stupid idea.” Transit officials would mix the clean white cars with dirty cars on the same train, so “you would have a pair of clean cars in the middle. You might as well have a sign that says, ‘Paint me next.’ ”…

Subway managers came up with a strategy: start with just two lines—the Number 4 and the Number 7—and clean the trains on those lines. And then keep them clean, washing and repainting to get rid of any new graffiti before trains could go out again, even at the expense of delays. This sent a clear message to vandals: spraying trains would no longer be worth the effort, since the MTA would never let customers see new graffiti. “It took 40 cans of paint and as much as 12 hours to complete a mural,” the New York Times reported a graffiti expert as saying. “Now it is hard even to snap a photograph before the work is cleaned off.”

Police also began cracking down on the vandals. Steve Mona was a “train buff growing up,” he says. He took the police exam and fortuitously “wound up in transit” in 1985, and soon had a new beat: keep tabs on the subways and see which graffiti tags appeared most frequently. “I would stop kids, and ask, ‘What does that say? Who is Jon156?’ ” He also started subscribing to graffiti zines. The city’s transit police (a separate force from the NYPD until 1995) eventually learned who was responsible for a disproportionate amount of the tagging and went after those people. “The narcotics mentality of ‘grab everyone, shake the net’ ” didn’t work in this context, Mona says. Instead, the vandal squad that he headed “would stake out homes, art shows,” looking for specific targets.

As Mona explains, the MTA’s new interest in combating graffiti made the police effort more effective. The district attorney’s office now had a graffiti victim, willing to testify: the MTA regularly sent witnesses to court, tallying up the damage from vandals so that prosecutors could pursue felony charges. “We had a built-in complainant,” Mona says. “The court could not look away from it.”…

The turnaround in the transit system accelerated in 1990, the year that William J. Bratton came to New York to head the transit cops, armed with sensible ideas from criminologist George Kelling. At the time, Kelling recalls, Kiley and Gunn, fresh from their graffiti victory, wanted to make the subway a safer, more welcoming place. They were frustrated by disorderly behavior such as aggressive panhandling, turnstile-jumping, and public urination—and frustrated, too, that the police seemed uninterested in doing anything about it. “The police would say, ‘We tried this and this, it didn’t work,’ ” says Kelling, “and Kiley blew up. He said, ‘We just invested $8 billion’ in new train cars and tracks. He was just sick. He couldn’t get any answers.”

Kelling was worried that the police, without the right strategy, would resort to “dirty work”—overly aggressive and perhaps illegal action to kick undesirable people out of the subways. Bratton and Kelling, who was consulting with the transit police, made clear that the cops would take the moral high ground, focusing on reducing illegal behavior underground and not on conditions. Homelessness was not a crime; jumping over a turnstile to avoid paying fare was. Going after illegal disorderly acts—what came to be known as Broken Windows or quality-of-life policing—would improve the lives of all New Yorkers who had to ride the trains to get around the city.

But before the laws against disorder could be enforced again, the public had to be warned. Every day, 250,000 people were beating the fare, Kelling notes, and “there were not 250,000 criminals—good people had got into bad habits.” They thought that the ride was not worth the money or they had gotten used to broken turnstiles, frequently disabled by thieves trying to take the valuable tokens. “You don’t want to arrest people, but the thing is to get them to stop,” says Kelling. The MTA launched a PR campaign to “warn people, educate people,” he adds.