The NYPD is urging the use of public transportation Wednesday afternoon as street closures and parking restrictions go into effect before the New Year's Eve celebration in Times Square.

Effective at 3 p.m. Times Square will be closed to vehicular traffic, the NYPD said in a news release.

"Attendees will be directed by police officers to gather in separate viewing sections," the NYPD said in a statement. "When one section reaches capacity, people will be directed to the next viewing section. As the evening progresses, revelers will continue to populate Times Square along Broadway and Seventh Avenue moving uptown from 43rd Street to Central Park."

The NYPD reminds revelers that alcoholic beverages, backpacks and large bags will be prohibited and "property may not be abandoned at checkpoints."

Those who leave before the ball drops "will not be able to gain entry to their original viewing area," the NYPD says.

Thousands of uniformed and plainclothes cops -- including all the recruits who graduated Monday -- are to police the event, expected to attract more than 1 million celebrants.

Asked about protesters joining the world's premier New Year's celebration, NYPD Chief of Department James P. O'Neill said Tuesday: "The pens fill up early. I mean, this is a long day. You know, people start getting there very early in the morning, so, unless you get there real early, you're probably not going to get close to the stage."

The NYPD's counterterrorism boss, John Miller, added, "Once they're closed, they're closed. People are free to leave. It's going to be hard to get back in, and I think the protesters will have to deal with that."

O'Neill said the NYPD would have additional personnel in case of protests.

Protesters would be subject to the same restrictions as everyone else, such as a limit on the size of bags and coolers, though placards aren't banned, O'Neill said.

The city has been beset with protests this month over a grand jury's decision not to indict a cop in the chokehold death of Eric Garner.

"Our policing philosophy is going to remain consistent," O'Neill said. "People have an absolute right to protest still, and as long as they do it peacefully and laws aren't broken, that's the way we're going to police the event."

The evening is to be monitored by choppers, chemical and radiological detectors, mounted units, scooters and foot patrol.

Those heading into the city to welcome the new year should bundle up tightly as the National Weather Service says wind chill values will make it feel like the mid to high teens when the ball drops.

And to help Long Islanders celebrate New Year's Eve and New Year's Day, the Long Island Rail Road is adding dozens of extra trains. But, officials warn, don't even think about bringing alcohol aboard.

As the railroad has done in prior years, alcohol will be banned from all trains, stations and railroad platforms beginning at noon on New Year's Eve until noon on New Year's Day.

Officials said the railroad will add 12 extra early afternoon eastbound trains on New Year's Eve on the Babylon, Ronkonkoma, Port Jefferson-Huntington, Port Washington and Far Rockaway branches.

There also will be 20 extra westbound trains systemwide on New Year's Eve.

Eighteen extra early morning eastbound trains have been added on New Year's Day.

With John Valenti and Gary Dymski