Officials are urging Washington-area residents to plan ahead to avoid nightmare commutes when the longest shutdown in Metro history begins Saturday, affecting six stations and an estimated 17,000 riders daily.

The 107-day shutdown of Blue and Yellow Line stations south of Reagan National Airport is the first phase of a three-year platform reconstruction project.

Braddock Road, King Street-Old Town, Eisenhower Avenue, Huntington, Van Dorn and Franconia-Springfield stations are scheduled to close at 1 a.m. Saturday and remain shuttered through Sept. 8. Metro will provide shuttle bus service, and area governments are beefing up their own bus services.

Officials also are encouraging commuters to seek other options such as carpooling and telework, lest large numbers of displaced Metro riders create a traffic nightmare on the region’s already gridlocked roads.

At a news conference Wednesday outlining the agency’s plans, Metro General Manager Paul J. Wiedefeld urged commuters to explore the options available and plan ahead for the return to work after the Memorial Day holiday — the first regular workday of the shutdown.

“To avoid confusion on Tuesday when everyone returns from the holiday weekend, please, please, please, make the plans now,” Wiedefeld said.

The work is scheduled for the summer, between Memorial Day and Labor Day, because ridership generally is lighter, officials said. But the platform work will continue during the remainder of the year, with some single-tracking and shorter shutdowns possible, the transit agency said.

The cost for the six-station project is about $200 million.

The shutdown is the most extensive Metro riders have had to endure since the disruptions of the year-long SafeTrack program, completed in mid-2017. And it’s only the beginning as the transit agency works to rebuild 20 station platforms by the end of 2021. Work next summer will affect the Green and Orange lines.

Transportation officials have been warning for months that this shutdown is a big one.

“This work will be hard on our riders and we are keenly aware of that,” said Metro board member Paul C. Smedberg, who represents Virginia. “But it is crucial to ensure the system’s reliability and more importantly to ensure customer safety.”

Said Alexandria transportation chief Yon Lambert: “This is definitely going to be a shock to the [transportation] system. It is going to take time for people to adjust to new routes and for the entire system to be able to absorb all of those commuters.”

This week, Metro staffers fanned out at Blue and Yellow Line stations to distribute fliers in English, Spanish and other languages, warning riders about the upcoming closures.

Starting Saturday, Metro employees will be outside affected stations directing commuters to shuttle buses that will ferry passengers from the six stations to other parts of the rail system. As many as 200 bus operators will be working on the massive plan to substitute buses for rail service.

Among other options are carpooling, a water taxi from Old Town Alexandria to the Wharf in the District, and biking. Capital Bikeshare, the region’s bike program, is offering discounted monthly passes.

Metro has created a trip planner at to help riders navigate the shutdown. The free shuttle buses available to commuters include express buses from the Huntington and Franconia-Springfield stations to the rail system and two shuttle routes with stops between affected stations. An express shuttle will take commuters from Landmark Mall to the Pentagon Metro station.

The best options, officials said, are telecommuting or traveling during ­off-peak hours. The Office of Personnel Management this week issued a memo urging federal agencies to allow more telework and alternative work schedules for their employees for the duration of the shutdown.

The worst option: driving.

“Do not get in your car and drive alone,” said alternate Metro board member Catherine M. Hudgins, who also is a Fairfax County supervisor. “This will only make things worse by creating gridlock on our roads and result in travel delays for all.”

Carolyn Mullen, a public health advocate who commutes by car from the Alexandria part of Fairfax County to Crystal City, worries that the shutdown, combined with construction at National and other road projects, could create traffic havoc. She worries about having a less predictable commute, where she might miss meetings or worse, be late to pick up her two children.

“Next week could be very difficult,” Mullen said. “This totally stresses me out.”

Madeleine Mitchell, a rug designer who runs a downtown D.C. gallery, lives in Old Town and boards the Blue line at King Street to get to McPherson Square daily. Pre-construction work at the King Street station has already made travel messy. It’s about to get worse.

“I am dreading it,” she said Wednesday at McPherson. “But we have no other choice, and I don’t want to drive.”

Virginia and transportation officials said their mitigation plans aim to discourage people from switching to driving by offering as many connections to public transit during the disruption as possible. But they warn riders to add at least 30 minutes to their trips, test a few commuting options to find the best one, and to be prepared for problems — especially in the first several days.

Metro’s experience during SafeTrack was that it takes a few days for commuters to adjust their travel patterns, and that those first days can bring operational challenges.

“We are prepared, but that does not mean it will be an easy week, as our experience has shown,” Wiedefeld said.

“Here is the good news: Awareness of the shutdown is very, very high,” Wiedefeld said. “But it is not enough to be aware. We need to make sure the customers understand their travel options and make plans now.”

By shutting down the system for several months, rather just on weekends, for example, “the disruptions, while acute,” are for as short a time as possible, Metro said.

The National Airport station will remain open, and travel north of the station should be normal. But officials are urging air travelers to add time to their trips to the airport. The shutdown, combined with major construction affecting the airport road network could create additional strains on National’s ground transportation. Airport officials are urging travelers to continue to use Metro.

“The airport expects to see a noticeable increase in passengers over the summer so it is important for travelers to familiarize themselves with the free shuttle bus options,” said Paul Malandrino, airport manager at National. “We encourage passengers to continue to take public transport to get to and from the airport. Normal train service will be available heading to the north, and shuttle bus service will be available heading to the south.”

The work is part of a three-year project to rebuild 20 of 45 outdoor platforms that Metro says are “structurally deficient” and pose safety risks to riders. Many of the platforms have been stabilized until the full reconstruction takes place, Metro said. But the reconstruction work is necessary, the agency said, to avoid an emergency shutdown.

This first phase affecting six stations will address other large-scale projects too, including the demolition of the unused south parking garage at Huntington, repairs of a rail bridge near the Van Dorn station, the installation of a new crossover near King Street, and the repair of another crossover at Huntington, according to Metro.

At Braddock Road, Metro plans to fix a problem known as the “Braddock hump” where the platform is out of alignment with train doors, resulting in a wheelchair impediment and a trip-and-fall hazard for exiting passengers.

“I exaggerate not by saying that the platforms that many of us crowd on as we access Metrorail, the terra from underneath, is not firm at all,” said Metro board member Christian Dorsey, who also is chair of the Arlington County Board. “With a finger, one can pick away the crumbling concrete.

“This is not an aesthetic issue. This is not just an issue that needs maintenance at some point in the future,” Dorsey said. “It is a risk each and every day that we have people crowding on those platforms. And while it can be very much said that the best time to have done this work would have been at some point in the past, the second best time to do it is absolutely right now.”