With heavy volume anticipated at New York City’s airports, bridges and tunnels during the pre-Christmas rush on Friday, the Port Authority is urging travelers to leave extra travel time.

Most transportation hubs will be busy during the holiday season, but traffic on LaGuardia Airport’s access roads has been difficult for the past six months during the initial stages of a multibillion-dollar reconstruction of the entire airport.

The Port Authority on Friday morning reported moderate traffic on LaGuardia roadways.

Travelers using LaGuardia can get a free bus ride or free parking Friday as officials try to ease the expected congestion.

The Metropolitan Transportation Authority said it is offering free rides Friday on its Q70 express bus to LaGuardia from the Long Island Rail Road station at Woodside and the subway station at 74th Street in Jackson Heights.

The Port Authority said it is providing free parking Friday at Lot P10, which connects to the passenger terminals by free shuttle buses. The free parking is on a first-come basis.

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“The holiday season is upon us, and we expect LaGuardia Central Terminal B and the entire airport to be busy — especially as our multibillion-dollar redevelopment project is underway,” an advisory from the developer said.

More than 103 million Americans are expected to travel during the holidays, up by 1.5 million from last year and the eighth straight year of year-end travel growth, AAA Northeast predicted.

That means about 32 percent of the population is expected to take a trip of 50 miles or more between Friday and Jan. 2, the auto club said.

Travel by automobile will account for 91 percent of trips, as usual for the Christmas and New Year’s holidays, AAA said.

For those hitting the roads on Long Island Friday afternoon there was at least one alert: Nassau County police reported at about 3:30 p.m. that the eastbound lanes of Sunrise Highway at Wantagh Avenue were closed due to a four-car accident. By 4:15 p.m. the lanes were reopen, police said.

For those who fly, the Transportation Security Administration advised arriving at the airport two hours before their flight.

AAA estimated that 6 million people will fly during the holidays, an increase of 2.5 percent from last year. “This will be the fifth consecutive year of rising air travel and the highest air travel volume since 2004,” AAA predicts.

For those getting an early start to the holiday, the Long Island Rail Road will operate 13 additional eastbound trains from Penn Station from 12:42 p.m. to 3:48 p.m. on Friday.

New York State said temporary lane closures for road and bridge construction projects will be suspended until 6 a.m. Tuesday this weekend and from 6 a.m. Friday, Dec. 30, to 6 a.m. Tuesday, Jan. 3. Some work may continue behind permanent concrete barriers or for emergency repairs, the state said.