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OAKLAND — Regional transit agencies boosted patrols after Monday’s pipe-bomb blast injured four people including the suspect in a subway at New York City’s Port Authority.

But BART authorities made it clear that commuters’ eyes and ears would be the keys to preventing a terrorist threat.

BART Police Chief Carlos Rojas joined a conference call with leaders of transit systems across the country to discuss efforts to prevent such attacks, BART Police Deputy Chief Edgar Alvarez said.

“This morning, we deployed our officers in an effort to be hyper-vigilant, and make sure that everything is where it’s supposed to be,” Alvarez said at a news conference at the Lake Merritt station. “But we’re letting our riders know that we can’t do this without them.”

In a system that carries up to 450,000 people per weekday and nearly 130 million riders a year, Alvarez said security tools like metal detectors “are not conducive to the movement of people we have,” and are less likely to be effective than riders’ use of the system’s BART Watch app to make anonymous reports of suspicious objects or people to station agents, train operators and dispatchers.

“Our district is unique that we intertwine with a lot of different allied agencies,” Alvarez said. “Our dogs are TSA-funded, and we have the VIPER team out there. We also go into SFO (San Francisco International Airport) and work in conjunction with San Francisco PD and their airport bureau.”

Other agencies across the Bay Area ramped up patrols.

In the South Bay, Santa Clara Valley Transportation Authority spokeswoman Linh Hoang vouched for VTA’s “purely precautionary” stepped-up efforts Monday.

“We want to assure our passengers that safety and security is VTA’s No. 1 priority. We have increased security patrols as is our standard protocol in these circumstances,” Hoang said.

“We continually evaluate our operations, security measures, and technologies to ensure that our transit system is safe for passengers and employees. In addition, the Santa Clara County Sheriff’s Transit Patrol, Allied Universal Security and VTA Fare Inspectors patrol our system to respond to incidents and suspicious activity.”

Hoang said system riders with smartphones should download and use the VTAlerts app to notify public-safety staff.

“We’re asking everyone to stay alert when you are traveling on our system,” Hoang said. “Passengers are usually the first to observe suspicious activities and medical emergencies.”

Other security measures added Monday included Homeland Security-trained officers from a VIPER — or visible intermodal prevention and response — team that is experienced in explosives and behavior-detection at airports and train stations.

Alvarez was accompanied by two of BART’s eight K-9 officers, whose animals must pass a six- to- eight-week-training program that tests their skill at picking out residue signatures for possible explosive materials.

“We’d take 50 dogs if we could,” Alvarez said. “With the number of people we move, we could probably handle 25 to 30, even 40 dogs. We’d take whatever we could get our hands on.”

Though that number would not allow officers to cost-effectively cover every station or checkpoint, Alvarez said BART was working with the Transportation Security Administration to see about acquiring more K-9s.

According to the Associated Press, the last bomb to go off in New York’s subway system was believed to be in December 1994, when an explosive made from mayonnaise jars and batteries wounded 48 people in a car in lower Manhattan. The Times Square subway station is the city’s busiest, with 64 million riders passing through every year. The subway system as a whole carried over 1.7 billion people last year.

Staff writer Jason Green contributed to this report. Contact George Kelly at 408-859-5180.