Security was increased on Metro-North and other lines run by the Metropolitan Transportation Authority since shortly after bin Laden's death last weekend, according to Jay H. Walder, MTA chairman.

This included adding more police officers, implementing bag checks and deploying heavy weapons units and police dog teams, he said.

He said the MTA was informed Thursday by the Department of Homeland Security that intelligence recovered from bin Laden's residence in Pakistan included notes about potential attacks on transit targets as the 10th anniversary of the 9/11 attacks approached.

Walder, in a memo to employees, said that "while this intelligence is non-specific, and we currently have no information regarding imminent threats," it's a reminder that transit networks remain "a top target of global terrorists."

In talking with reporters during an event in Stamford on Friday, U.S. Sen. Joe Lieberman, I-Conn., said the handwritten notes found in bin Laden's compound contemplating an attack on a U.S. rail facility are just the latest and most tangible evidence of what he and others have assumed would be a target for years.

"That's simply because rail lines, metro systems and subway systems have been hit in Mumbai and Madrid and London, etc." Lieberman said. "It's part of why we're working to really strengthen security on rail systems, including here in Connecticut, some of which people can see, some of which they can't see."

Since trains have far less security than air travel, Lieberman said he worries terrorists will view them as a potential target.

"I think we've got to continue to try to beef up rail security, and, of course, we rely immensely on intelligence," Lieberman said. "When you're dealing with terrorists, intelligence is the most important asset you have because you want to see what's coming at you before it comes at you so you can stop it."

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If you see something ... Anyone who sees something suspicious is asked to speak to a uniformed officer or transit system official, such as a conductor or other employee, or call the Department of Emergency Management and Homeland Security 24-hour homeland security tip line at 1-866-HLS-TIPS. If immediate attention is necessary, call 911.

Even before the latest news of a potential terror plot, an aggressive security awareness campaign -- "If You See Something, Say Something" -- was launched. It aims to empower people to monitor their own environment for suspicious objects or behavior on trains or buses, at stations and other public places.

"This common-sense campaign is one of the most effective ways to keep authorities informed and protect us from potential threats," Gov. Dannel P. Malloy said in a news release. "As you go about your daily routines, make sure you are aware of your surroundings and recognize when something looks out of place or suspicious."

Metro North also began using the campaign, Walder said. He said it's a message "we all need to take to heart" as we ride the rail system.

The state also recently added a State Police Mass Security Unit that includes five canine explosive detection teams. The teams will be deployed to conduct proactive explosive detection sweeps at passenger rail and bus stations and terminals, according the state Department of Transportation.

"It is important to assure Connecticut residents that these units will be on patrol each and every day and that they represent an added layer of security," state Department of Public Safety Commissioner Reuben Bradford added.

"The appearance of these security units will become a part of everyday life on our trains and in and around our rail and bus stations," he said.

Back in Fairfield, a group of young teens were also heading to New York City Friday. They were going for a day of fun.

"I'm kinda nervous, kinda worried," said Shawn Rice, 17, of Trumbull. "But that's not going to stop me."

But his friend, Julia Bobbitt, 17, of Fairfield, was a little more apprehensive.

"I'm not really that concerned, but it's still a little nerve-wracking when you think about what might happen," she said.

Staff Writer John Nickerson contributed to this report.