The Metro-North Railroad employee accused of a lewd act involving a female passenger pleaded not guilty Tuesday to the charges in Bridgeport Superior Court.

Manny Ramos, 35, of Brooklyn, N.Y., who police said confessed to masturbating on a sleeping pregnant woman on a New Haven Line train because he was under stress at work and home, pleaded not guilty to fourth-degree sexual assault, public indecency and second-degree breach of peace.

With his lawyer, Bruce Koffsky of Stamford, at his side in Bridgeport Superior Court he chose a trial by jury.

If convicted of fourth-degree sexual assault, a misdemeanor, Ramos will be listed on the state's sex offender registry, which is a way for the public to track predators and other sex criminals.

Witnesses said that a bag that Ramos carried with him in court held a towel, but it was unclear why he had it with him -- although court appearances can prove stressful.

Judge Earl Richards continued the case to March 11.

Koffsky and Ramos declined comment as they left the Golden Hill Street courthouse.

Assistant State's Attorney Tatiana Messina on Tuesday added the fourth-degree sexual assault charge to those already filed against Ramos, who was captured in Fairfield a short distance away from the downtown train station where he fled the train. "I believe it is the appropriate charge based on the evidence," she told the judge.

Ramos could face up to two years in prison if convicted of all the charges.

In training to become an engineer for Metro-North, Ramos is accused of masturbating on the napping woman at about 8 a.m. Jan. 28 on a train traveling from Grand Central Station to New Haven.

After she opened her eyes and saw Ramos with his pants unzipped, the 33-year-old medical researcher at Yale University told police she yelled and startled him. Police said the woman then screamed for other passengers to stop Ramos as he fled the train when it reached the Fairfield station, but no one helped.

Ramos was arrested by Fairfield police as he was walking from the station on the Unquowa Road overpass.

Prior to studying to become a train engineer, Ramos was a manual laborer who cleaned coaches for the railroad.

Ramos later gave a written confession, according to police reports, stating he was under a lot of stress because of problems with his wife and because he was about to take a final test to become an engineer for the railroad.

"I was studying for the test when I started to have unwanted thoughts," he told MTA police. "I began to touch myself when I felt ill with a headache and stressed, the next thing I knew I was masturbating."