A multibillion-dollar reinvention of LaGuardia Airport into a 21st-century transit hub is causing travel pain on the ground — and it could last for years.

Any given day at LaGuardia — which Vice President Joe Biden has compared to an airport in “some Third World country” — can become a navigational nightmare. Drivers must contend with constantly changing traffic lanes as hundreds of construction workers and heavy equipment labor behind chain-link fences. Exasperated travelers sometimes get out of their bumper-to-bumper taxis and just walk to the terminals.

The project began amid fanfare as Gov. Andrew M. Cuomo symbolically broke ground for a new Central Terminal Building at a June 14 ceremony attended by Biden.

“It’s going to be a whole new airport — one unified, contiguous, state-of-the-art airport for the first time,” Cuomo had said.

But until the work is done, traveler Elmira Bayrasli of Brooklyn, an author and lecturer on emerging markets, said she will try to avoid LaGuardia altogether.

“It’s just one big, angry parking lot,” she said.

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Earlier this year, Patrick Foye, executive director of the Port Authority, which operates LaGuardia, acknowledged the summer traffic problems and called the prospect of essentially building a new airport while the current one is in operation “challenging.”

“This is LaGuardia,” he said. “We can’t shut it down.”

A second phase of renovations, set to begin in 2018, could mean the travel hassle won’t end anytime soon.

The new Central Terminal Building, also known as Terminal B, and its nine airlines eventually will be linked to a new Delta terminal next door after the airline demolishes its two existing terminals.

Elmira Bayrasli, co-founder of Foreign Policy Interrupted and the author of From the Other Side of the World: Extraordinary Entrepreneurs, pictured at her Brooklyn home, on Dec. 5, 2016, said she tries to avoid LaGuardia Airport, which she described as "one big, angry parking lot." Photo Credit: Yeong-Ung Yang

Some parts of the new central terminal will be open to the public by 2018 and it will be fully open by 2021, Cuomo said in June. Officials have given no target date for completion of the entire project, which is expected to cost nearly $8 billion.

But since construction began, complaints on social media have been constant — mostly about the handling of automobile traffic leading into and out of the airport.

“Hell is probably very similar to LaGuardia Airport traffic,” Twitter user @Hall_OrNothin tweeted on Dec. 4.

“LaGuardia Airport. 45 minute wait for bags, traffic jam outside,” tweeted @saidnickfox on Nov. 30.

“I know they’re trying to fix LaGuardia, but unless they do a serious overhaul of all the buildings and refigure traffic patterns, it won’t help,” Bayrasli said. “It’s an awful experience to fly in and out of. Just awful.”

Attorney Robert Calica, pictured at his office in Garden City on Dec. 6, 2016, said he's ruling out LaGuardia Airport after trouble with traffic there on a recent trip. Photo Credit: Raychel Brightman

The Port Authority conceded that there were problems with traffic flow last summer but said things have gotten better.

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“Traffic issues that we experienced in early August . . . have not been replicated,” Foye said after a meeting of the agency’s board last month.

That’s news to Garden City attorney Robert Calica, who flew out of LaGuardia to Florida on Dec. 1 and said “traffic was a mess.”

“LaGuardia is out of contention for me for the next couple of years,” said Calica, who flies to the Sunshine State about six times a year.

“It’s even affected my commute into Manhattan when I see clients,” Calica said. His traffic app directs him away from the Grand Central Parkway next to the airport and reroutes him through the Bronx, he said.

Jason Gantt, a Connecticut resident and frequent business traveler, tows his luggage after arriving on a flight that landed at the Westchester County Airport Thursday, Nov. 17, 2016. Gantt braved the traffic during the first few months after construction began in June, then gave up. Photo Credit: Craig Ruttle

When Calica called a car service to take him to the airport for his Dec. 1 trip, the company emailed him a notice that officials have been warning travelers to get to LaGuardia two to 2 1/2 hours before their scheduled departure time.

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“Traffic patterns within the airport often change without notice and the roads inside and around LGA get very congested,” the email read.

Frequent business traveler Jason Gantt of Fairfield, Connecticut, braved the traffic during the first few months after construction began in June, then gave up.

“For the time being, I just can’t use LaGuardia,” said Gantt, who works in financial services. On most recent trips he has been flying out of smaller airports near Hartford, Connecticut, and in Westchester County that have fewer flights to fewer destinations.

“After construction is finished, out of necessity I’ll come back to LaGuardia,” he said. “The economics are better. The choices [of flights] are better.”

A passenger hoofs it on Aug. 24, 2016, to a temporary taxi stand outside Terminal B at LaGuardia Airport. Photo Credit: AP / Kathy Willens

The construction activity, however, does not seem to have deterred most travelers from using LaGuardia. It handled 10.6 million customers from July through October — about 375,000 more than the same four months last year, the Port Authority said.

Airline operations also have shown no significant impact.

Data from the U.S. Department of Transportation show an on-time rate of 83 percent for arrivals this October — the last month for which data are available — compared with 81.4 percent in October 2015.

Departures were on schedule 82.6 percent of the time this October, compared with 83.6 percent of the time during the same month last year, according to the federal agency.

Although many travelers are angry about the traffic congestion on airport roadways, the taxi and car service drivers who navigate the roads daily seem mostly resigned to the need for short-term pain to modernize the aging airport, which opened in 1939.

“It’s all construction. I don’t know what you could do about construction,” driver Pierre Medor, 62, said after dropping off a fare at the curb of the main terminal.

Yellow taxi driver Kevin Franklin, 49, said there was little that could be done to improve his daily drives to LaGuardia. “It narrows to one lane there,” he said, pointing to the exit road from the main terminal. “Maybe they could make it two lanes.”

One LaGuardia advisory on social media occasionally tells motorists: “Think opposite. Use arrival levels for drop-off & departure level for pickup.”

That’s a soft spot that some car-service drivers have used, parking in departures on outer lanes supposedly reserved for airport shuttles that has minimal traffic enforcement.

The Port Authority would not directly address whether last summer’s traffic problems are continuing, instead saying in a statement that it had taken “dozens of proactive and aggressive measures to reduce congestion.” They include deploying more police officers, reconfiguring traffic patterns and creating a traffic command center.

Stewart Steeves, head of LaGuardia Gateway Partners, the private consortium reconstructing the terminal, said in an interview that “there have been a couple of traffic situations that have been unacceptable to all of us.”

For the past six months, the Port Authority and the consortium have been issuing separate traffic advisories, not always at the same time or about the same conditions.

“We’re working very closely with Port Authority to ensure the flow of traffic is maintained to the extent possible,” Steeves said.

In an effort to limit the number of motorists who drive to the main terminals, the Port Authority said on Dec. 7 that it would permanently hike daily parking rates in lots closest to the main terminal, while temporarily reducing them during the holiday season at the remote, long-term lot — a 10-minute shuttle ride away from the terminal.

“We initiated a discount parking fee to encourage better use of our remote, long-term parking lot,” the agency said in a statement.

There are about 4,200 parking spots at the airport, down from 6,400 because of the demolition of the main parking garage and a change in the location of parking areas. That should be remedied when a new garage opens in 2018, officials said.

The Port Authority also is urging travelers to use express buses and local bus routes that serve the airport, and says that the planned construction of a train link to the Queens subway system eventually will lessen traffic. However, the train proposal is bogged down in a dispute between New York and New Jersey on how the Port Authority allocates billions of dollars on major projects in each state.

LaGuardia has been handling about 25 million passengers annually in recent years, and that is projected to grow by 6 million within 20 years.

The Port Authority says the only way to handle the increase is to modernize the terminals so they can accommodate larger planes.

Lengthening the runways — the shortest of any major American airport — was ruled out because LaGuardia is bracketed by the Grand Central Parkway and housing on the south, and Flushing Bay and the East River on the north.

The new main terminal will be built closer to the Grand Central Parkway, creating more space on taxiway areas and improving the flow between runways and terminals, the Port Authority said.

In addition to a new terminal, LaGuardia Gateway Partners is building access roads for the entire airport. While the consortium will operate its terminal, the access roads will remain under control of the Port Authority.

Traffic isn’t the only concern. The Global Gateway Alliance, a corporate group advocating airport development, said it appeared that automobile traffic had gotten better recently, but more should be done to clean up the main terminal before the new one opens.

The developers “should focus on relatively [simple] fixes to the current terminal, like stopping water leaks in the ceiling, to improve quality of life for passengers during a yearslong construction period,” Joe Sitt, the alliance chairman, said in a statement.

Steeves said that work has begun and $5 million has been set aside for it.

When Terminal B opened in 1964, it was designed to handle 8 million passengers a year — but now handles more than 13 million annually, with up to 50,000 on any given day, Steeves said.

“The challenge that exists for us is that the airport has twice the demand of capacity,” he said.

All of these woes came during just the first phase of construction. The second phase of the LaGuardia renovation will be the creation of a new home for Delta Air Lines where Terminals C and D now stand, just to the east of the main terminal.

Some of the Delta work can proceed at the same time as construction on the main terminal, officials said, but the Delta portion must undergo a separate environmental review and get permits from the Federal Aviation Administration.

Each phase of the project is expected to cost about $4 billion under provisions of 35-year leases with Delta and the consortium for the terminals. The bulk of the $8 billion will come from private investments that will be recouped through fees from passengers and airlines, and revenue from food and other concessions, the Port Authority said.

The cost does not include work the Port Authority has done in recent years in preparation for the project.

There is no construction schedule for the Delta phase of the project, but Port Authority chairman John Degnan at the September board meeting raised the possibility of a new round of traffic headaches when that happens.

“Are we going to create a traffic Armageddon?” he asked.