Compared with the aura of security offered by riding inside of an automobile, many people avoid transit because they feel vulnerable and threatened by other riders.

Crime, sexual harassment, and other invasions of privacy are common on metro systems throughout the world. Sexual harassment is especially bad on Tokyo subways, and a survey of 600 women transit riders in Paris found that 100 percent of them reported having been sexually harassed.

Such harassment often depends on the anonymity that comes with extreme crowding, but most American transit systems don’t get that crowded precisely because Americans won’t accept the invasions of personal space required for such crush conditions. Still, there are numerous complaints of sexual harassment on the New York City subway. Crime is rapidly rising on the DC Metro as well.

Crime, including thefts of smart phones, as well as violent crime, can be a big problem on light rail, partly because there is rarely anyone aboard to keep vehicles secure. Bus drivers presumably provide a modest deterrent to crime, but still there is the problem of bus-stop crime.

Some researchers argue that transit doesn’t really increase crime near transit stations. But for potential transit riders, perception trumps reality. A woman may only have to suffer one or two experiences with groping or other forms of sexual harassment before she decides to never ride transit again. A man who is beaten and robbed of his coat because the coat happened to match a particular gang’s colors is also going to avoid transit.

Some transit systems have designated women-only cars to protect women from harassment, but results have been mixed. Short of putting a guard on every bus and railcar, the issue of transit security cannot be easily solved.