What to Do if Violence Breaks Out on Your Train or Bus

A recent shooting on an A train in Brooklyn left some subway riders feeling unsettled, and questioning how they might respond if such a violent clash took place on their train car, bus or other mode of public transportation.

Experts say that public transportation is not uniquely dangerous, and even in New York City, the perception of crime on the subway has eclipsed what the actual data reveals.

Still, it can be helpful to know what public safety experts believe to be the best ways to protect yourself while using transit.

Here’s what to know.

Be alert for dangerous situations.

Tracy Walder, who has worked for the C.I.A. and F.B.I., recommends being alert for people who appear to be “extremely anxious,” such as those who cannot sit still, and those who engage in verbal harassment, though she adds that many people who engage in those behaviors don’t harm others or commit crimes.

“Usually how these start is, it escalates,” she said. “It would start with a verbal harassment and then escalate into physical harassment.”

It’s also essential to focus on the right factors.

“If you monitor your surroundings, don’t judge the people by their appearance. Judge them by their behavior,” said Michal Cieslik, the chair of the security committee of the International Association of Public Transport.

Choosing where to sit, and other pointers.

Ms. Walder encourages starting with preparation. She said riders should always stay awake and alert on public transportation. She also suggests that riders try to sit in the operator or conductor cars — typically the first and middle cars on New York City trains — and avoid the doors, because she said transit users are more likely to be harassed near them.

Wary riders could also consider avoiding the end cars, especially at night when those areas might be less crowded, and they might want to avoid eye contact with strangers.

“If you are hearing verbal harassment, do not talk back because you are just going to escalate the situation 100 percent of the time,” she said.

Many train systems have intercoms that riders can use to contact the conductor. Riders can also contact other transit employees or immediately call 911 if they have cellular service underground.

When should you pull the emergency brake?

Ms. Walder cautioned against pulling the emergency brake, especially in big cities, because it can be faster to get help if you wait to arrive at the next stop, get off and contact emergency responders then. Pulling the emergency brake means the train could stop in a tunnel, and you would have to wait for help.

Consider moving to another car.

It can be a good idea to switch train cars if you feel uncomfortable, preferably by waiting for the next stop, Ms. Walder said. The Metropolitan Transportation Authority, for example, urges riders not to pass between moving cars because the practice can be deadly.

What about open carriages?

Open carriages, or long trains without separate cars, have become the norm globally, Mr. Cieslik said. He said the carriages make it easier to escape a situation because there is no door to slow people down.

“You’re much quicker in evasive actions in case of an attack,” he said.

However, the open-carriage system can also make it “more difficult to contain the carnage” in a violent scenario, Ms. Walder said.

Seeking help from bystanders.

What if you are being harassed and no one is helping you?

Sometimes people don’t step up to help because they believe others will, said Chandra Bhat, who is president of the Transportation and Development Institute of the American Society of Civil Engineers.

Bystanders may also not realize what is happening.

“One thing is to just be a little bit vociferous and ask for help to indicate a situation that is making you uncomfortable,” Mr. Bhat said, adding that this also sends a message to the aggressor.

It is best to be brief. “People get a little upset and then they start saying too many things that can actually escalate the situation,” he said.

Mr. Cieslik also encourages putting as much distance between yourself and the aggressor as possible, and using your phone to make a recording.

Knowing when to intervene.

Tsahi Shemesh, the founder and chief instructor of Krav Maga Experts, a New York City-based organization that teaches self-defense classes, said that ultimately “the answer is, do what you can,” adding that not everyone has the same capabilities and that every situation is different.

“In fact, if I don’t know what I’m doing, and if I don’t have the authority to stop it, I may just become another victim,” he said, adding that sometimes doing nothing is the best decision if you’re not trained.

But he said that “being unequipped is a dangerous decision,” and that people should learn self-defense.

Polly Hanson, a senior director for the American Public Transportation Association, said “the decision to intervene in a nonconfrontational way is a personal decision and the transit authority is going to encourage people to report things, not to intervene.”

If you witness an attack, Mr. Shemesh said that sometimes it is helpful to be loud and call attention to the situation or check later on the victim, if there is one, to make sure that they know someone is watching and cares.

“People tend to do absolutely nothing when they see an attack,” he said, adding that it’s not because they don’t want to help but “because they don’t know how to help.”

If you are a witness, should you record?

Passengers should record an incident with their phone cameras only if they are out of harm’s way. Law enforcement officials have used phone camera footage to secure convictions and to piece together crime scenes, Ms. Walder said.

Mr. Bhat noted that sometimes people change their behavior when they know they are on video.

“Sometimes it can be a way to diffuse, because most people, as soon as they realize that the recording is happening, they start getting into a little bit more of a softer tone,” he said.