Tens of thousands of subway riders will soon feel the brunt of Metro’s long-term maintenance overhaul as the transit agency, starting Saturday, closes a heavily traveled stretch of three rail lines for 16 days. The shutdown will result in major service reductions in downtown Washington and force Blue Line commuters from Virginia to take more cumbersome routes into and out of the city.

“I would stress very strongly that people telework or carpool into their jobs,” Metro General Manager Paul J. Wiedefeld said at a Thursday news conference.

Like D.C. Mayor Muriel E. Bowser (D) and Prince George’s County Executive Rushern L. Baker III (D), who appeared with him, Wiedefeld implored commuters in the shutdown area, near the D.C.-Prince George’s border, to refrain from using Metro if possible.

“This is going to put a tremendous stress on residents coming into the District” from Prince George’s, Baker said. “So we want people to start thinking now. . . . We want people to start making plans for other alternatives for coming into the city.”

The 16-day project is the second of 15 maintenance “surges” scheduled to be carried out in Metro’s months-long SafeTrack rebuilding effort. Officials are trying to revitalize a subway that has fallen into dangerous disrepair because of decades of maintenance neglect, resulting in chronic breakdowns and safety problems.

Here's what Blue Line riders need to know about how the second phase of Metro's maintenance plan, known as SafeTrack will affect them. The second phase runs June 18-July 3 on the Blue Line. (Claritza Jimenez,Danielle Kunitz/The Washington Post)

The first SafeTrack project, scheduled to be finished Thursday, caused service delays on the Orange and Silver lines for two weeks, with trains traveling in both directions forced to share one track between the East Falls Church and Ballston stations.

But that single-tracking on the subway’s western side was a relatively small aggravation compared with the next disruption, which will be centered on the system’s eastern side. From Saturday through July 3, rail service will be halted from the Eastern Market station, on the Orange, Silver and Blue lines, to the Orange Line’s Minnesota Avenue station and to the Benning Road station on the Silver and Blue lines.

For people who have no choice but to use the subway, Metro will provide shuttle buses to ferry them past the Stadium-Armory and Potomac Avenue stations, which will be shuttered for 16 days. However, there will not be nearly enough buses to carry the tens of thousands of rail commuters who normally ride in that area, transit officials warned.

“They should allow well over an hour of additional travel time,” Metro spokesman Dan Stessel said of shuttle bus riders. “Expect crowding. Expect it to be hot. Expect it to be frustrating. It’s not going to be a pleasant experience.”

Four partial rail-line shutdowns in other areas of the system — two in July and one each in October and December — also are scheduled as part of the SafeTrack effort.

The year-long Metrorail rehabilitation plan includes 15 projects that will require the longest stretches of single-tracking and station shutdowns.

While Metro riders who live in Prince George’s or in the District’s eastern corner and work downtown will bear the worst of this month’s inconvenience, the ripple effects of the shutdown will be felt all along the Orange, Silver and Blue lines, especially by Blue Line commuters who travel into the city from the Alexandria area.

For example, to ease train traffic in downtown Washington, Blue Line trains will run only between the Franconia-Springfield station and Arlington National Cemetery, “and only during the hours that the cemetery is open,” Wiedefeld said. From April to September, the cemetery is open to the public from 8 a.m. to 7 p.m., according to its website.

Riders headed downtown on Orange Line trains that originate at the New Carrollton station will have to get off at Minnesota Avenue. On the Silver Line, trains that start at the Largo Town Center station will terminate at Benning Road.

From Minnesota Avenue and Benning Road, shuttle buses will carry riders to Eastern Market, where they can board trains again and head downtown. For eastbound riders headed out of downtown, shuttle buses will be available from Eastern Market to Minnesota Avenue and to Benning Road.

But Metro warned that the buses will be able to accommodate only about 30 percent of the tens of thousands of riders who normally use that part of the system in rush hours.

“For this to be successful, we need 7 out of 10 people east of Eastern Market to do something different, or crowding [on shuttle buses] is going to be quite severe,” Stessel said. “The message is, if you live east of Eastern Market, and you don’t have a plan yet, then you need to get one now. . . . The reason for the bus service is for customers who have absolutely no other option.”

He said: “There’s no way for buses to replicate the capacity of three rail lines. In rush hours, trains move through this section every two minutes and 20 seconds, and the trains have up to 800 people on them. So do the math. A bus holds roughly 50 people. So every two minutes and 20 seconds, you’d need 16 buses, and that’s only one direction. And there aren’t enough buses in the region to handle that.”

Riders who get off trains at Minnesota Avenue or Benning Road and get back on at Eastern Market, or vice versa, will be charged for “a single continuous trip” and not assessed the added fare associated with leaving and reentering the system, Metro said.

Between the Rosslyn and Stadium-Armory stations, the Orange, Blue and Silver lines share tracks across downtown Washington. Normally, trains arrive at stations along that stretch at a rate of about 26 per hour during the morning and evening rush hours and about 16 per hour during the midday periods, according to Metro.

With no Blue Line service beyond Arlington Cemetery during the 16-day surge, and Orange and Silver line service reduced, trains will arrive at a rate of about 11 per hour at the stations from Rosslyn to Stadium-Armory, the transit agency said. That translates to a rush-hour service reduction of more than 50 percent.

All told, Metro said, closing the Stadium-Armory and Potomac Avenue stations, reducing service along the rest of the Orange and Silver lines and limiting the Blue Line to a short route in Virginia will disrupt about 293,000 rush-hour train trips per day.

And that will make for crowded platforms and trains. How crowded they will be depends on how many people heed Metro’s warning to avoid the subway.

“We’re just asking everybody to think about their commutes ahead of time and think about alternatives,” Bowser said. “We want people to carpool if you’re going to be in a vehicle to get to work. And there are many options for telework certainly.”

Wiedefeld and other officials also urged people to stay away from the subway and shuttle buses by commuting on regular Metrobuses or smaller bus services.

With Blue Line trains from Franconia-Springfield running only as far as Arlington Cemetery, and not running at all when the cemetery is closed, riders headed downtown will have to take a route that will be much less convenient for many of them.

Yellow Line service will be expanded to include the Franconia-Springfield station, in place of Blue Line trains. But the Yellow Line, after crossing the Potomac River well south of Rosslyn, makes its first stop in the District at the L’Enfant Plaza station, There, commuters who normally have a single-seat ride on the Blue Line will have to switch to the Orange or Silver lines to travel east or west to their destinations.

Metro said it plans a massive overhaul in the shutdown area, including replacing rails, rail ties, electrical insulators, cables and cable connector assemblies, as well as clearing trash, cleaning drains, upgrading lights and fixing water leaks.

In addition to the five partial rail-line shutdowns that are part of SafeTrack, the months-long effort includes 10 projects, somewhat less disruptive, that will require single-tracking so that crew will have space in which to work. The first of those 10 projects, between Ballston and East Falls Church, was due to wrap up Thursday night.

And no SafeTrack work is scheduled for Friday.

“There will be normal service,” Stessel said, calling it “a one-day reprieve” before the shutdown starts Saturday and riders truly feel the pain in the Monday morning rush hour.