For many thousands of Metro commuters coping with a partial shutdown of the Orange, Silver and Blue lines Monday, summer’s first rush hours meant reduced train service and waiting for shuttle buses in the heat. Yet the disruption, although it caused plenty of griping, turned out to be manageable thanks to lower-than-normal rail ridership, officials said.

On the third full day — but the first workday — of Metro’s latest SafeTrack maintenance project, which will continue until July 3, the choke point stretches from the Eastern Market station, on the Orange, Silver and Blue lines, to the Orange Line’s Minnesota Avenue station and the Benning Road station on the Silver and Blue lines.

The Potomac Avenue and Stadium-Armory stations are closed; direct rail access between Prince George’s County and downtown Washington is cut off; Orange and Silver trains are running less frequently; and there is no Blue Line service in the city.

Still, the aggravation seemed under control, at least to start the week.

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

Metro had warned that shuttle buses would only be able to accommodate about 30 percent of the tens of the thousands of commuters who typically use that part of the system during rush hour. So, it needed about 70 percent of those riders, living in Prince George’s and the District’s eastern corner, to find other routes into and out of downtown.

“Fortunately, that’s exactly what happened,” Metro spokesman Dan Stessel said Monday afternoon. Inbound morning ridership from the New Carrollton station to Minnesota Avenue and from the Largo Town Center station to Benning Road was down about 65 percent compared with last Monday, and Stessel said Metro was confident that ridership in the work zone Monday evening would be similarly light.

“Now, we need everyone to do the same thing [Tuesday] and every day” until the track-work project ends July 3, he said.

Metro General Manager Paul J. Wiedefeld was at Benning Road early Monday and said he was pleased by what appeared to be lighter-than-normal commuter traffic.

“We’re right at the limit, I believe, of what we can handle,” Wiedefeld said, referring to the shuttle buses.

The current 16-day project, which began Saturday, is the second of 15 scheduled maintenance “surges,” including five that involve partial rail-line shutdowns. The projects are part of the transit agency’s nearly year-long SafeTrack program of infrastructure upgrades, designed to revitalize and improve safety in the 40-year-old, failure-prone subway system after decades of neglect.

Riders headed into the city from Prince George’s and the District’s eastern corner have to exit trains at Minnesota Avenue and Benning Road. From there, shuttles are ferrying them to Eastern Market, where they can reboard the subway.

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 morning of the SafeTrack surge unfolded without incident, as many potential users seemed to have heeded the message to plan ahead,” said Paulette Jones, spokeswoman for the Prince George’s County Department of Public Works and Transportation. “Many seem to have opted to telework or shift work schedules, and we have seen increased usage at Green Line stations for access into the District and other points.”

She said there were no long lines for shuttle buses, as officials had feared. But, she said Monday’s relatively smooth commute should not be “misinterpreted.”

“This is a Monday morning in early summer,” she said. “It is a day that a lot of people normally take off or use a flex day. We will probably have a better feel for the real impacts [Tuesday]. But in any case, it is important that the message taken from this is not that the SafeTrack surge has been mitigated and people can return to the system.”

At 8 a.m. Monday, commuters at Stadium-Armory encountered no lines and short waits for shuttles to Eastern Market, Benning Road and Minnesota Avenue. Jenny Devine, a federal worker who lives a block from Stadium-Armory, was surprised at how quiet it was. Headed to work, she had left home 15 minutes early to cover any delay.

“It doesn’t look that bad so far,” said Devine, who works at the Department of Agriculture. “I expected a lot more people here.”

When trains pulled into the Benning Road station early Monday, commuters rushed out, hurrying toward the buses parked nearby. The shuttles filled quickly. “No more room,” warned one driver, who directed a line of riders to the bus behind him.

Andre Shields, 23, was waiting in line for a shuttle bus to Eastern Market so he could eventually get to Woodley Park, where he works as a cook. He had boarded a Silver Line train at the Capitol Heights station. Even though the shutdown had been well publicized, Shields, like others in his rail car, was surprised when his ride terminated at Benning Road.

“They should have a better system than this,” he said. Because of the shuttle ride and a transfer to the Red Line at Metro Center, he knew he would be late for his 8 a.m. shift.

MARC commuter trains on the Penn Line from Baltimore to Washington Union Station on Monday picked up hundreds more commuters than on a normal Monday, the Maryland Transit Administration said.

Inside the District’s Joint All-Hazards Operations Center, where officials are stationed to respond to blizzards, tanker spills or terrorist attacks, extra eyes were on 15 traffic-monitoring screens showing jerky images of traffic many had feared would be massive gridlock.

But the day that unfolded was pretty normal.

Officials said a combination of increased police presence at dozens of intersections, moves to lengthen green lights in hot spots, and thousands of individual decisions by drivers combined to keep cars flowing – or inching along – on balance as they would on a typical day.

Many factors — including District schools being out and people vacationing or working from home — may have lessened the pressure.

“It’s a Monday in the summertime. I still would have expected to see more,” said Nicole A. Chapple, an assistant director at the District’s Homeland Security and Emergency Management Agency. But “this may look very different” as the week unfolds.

One outlier Monday was, perhaps not surprisingly, a stretch of Pennsylvania Avenue SE running from Independence Avenue to the Anacostia River — and right past the shuttered Potomac Avenue Metro station. Westbound traffic there on recent Mondays at 8 a.m. moved about 20 mph, according to the traffic data firm Inrix. On Monday, the average speed dropped to 8.6 mph.

“So far, many roads don’t show signs of significantly increased congestion over previous Mondays,” said Inrix senior economist Bob Pishue, citing early data from New York Avenue, Benning Road and Interstate 695, three key commuter routes. “Pennsylvania Avenue is the exception.”

But, Pishue cautioned, Mondays aren’t necessarily representative, given they are generally lighter traffic days. There can also be a circular nature to driver behavior. “They see it’s not as bad, then they head out tomorrow, and then it gets bad,” he said.

While traffic on Pennsylvania Avenue moved slower than usual, it moved faster than normal in other places.

“That’s normally gridlocked when people block the box,” said D.C. Police Capt. Robert Glover, peering at images from Benning Road and East Capitol Street NE, near the Benning Road Metro station. But police and traffic control officers from the District Department of Transportation were out in force. “That intersection is flowing reasonably well,” Glover said.

Three Metro workers were at the Potomac Avenue Metro station, directing commuters to shuttle buses. Teyonka Hodge, 32, who lives a few blocks from the Potomac station, said she wasn’t aware of the shutdown before she arrived there Monday. She was trying to get to the National Institutes of Health in Bethesda for the start of her 7 a.m. shift.

“Where have you been the past few weeks?” a Metro worker asked Hodge, surprised that she hadn’t heard about SafeTrack.

“I haven’t been watching the news,” Hodge replied. “I didn’t realize this was going on. I’ll need to get up earlier. I can’t afford to be late.”

Stephon Heyer, who lives in Southeast Washington and begins his daily commute at Potomac Avenue, said he was not aware of the shutdown until Sunday, when he saw signs at the station on his way to pick up his son for Father’s Day.

“I didn’t expect it to be so soon; I thought it would happen later in the summer,” said Heyer, who works near the Van Ness station, a trip that normally takes him about 30 minutes. It will take longer, though, during the surge.

“I have to wait for the shuttle, and I don’t even know what the trains will be like yet,” he said. “It’ll probably take an hour, an hour and 15 minutes, to get to work.”

To ease train congestion through downtown Washington during the 16-day project, Blue Line trains are running only in the Alexandria area, and only during certain hours. To reach the city from there, commuters have to take Yellow Line trains to L’Enfant Plaza.

D.C.-bound Yellow Line trains are running not only from the Huntington station, as they normally do, but also from the Blue Line’s Franconia-Springfield station.

This led to more crowding than normal on the L’Enfant Plaza station platforms, where many people who usually ride the Blue Line had to switch trains — from the Yellow to the Orange or Silver — to reach their destinations.

This caused some confusion Monday, at least initially.

“Oh, my God! Oh, my God!” said Lutgarda O’Campo, 65, of Dumfries, Va., as she awaited a train at the King Street-Old Town station in Alexandria.

She normally rides the Blue Line from there to Rosslyn, then switches to an Orange or Silver train to get to work at a bank in Ballston. But like some other commuters Monday, she was in the dark about the shutdown and surprised that no Blue Line trains were going to Rosslyn. “I didn’t know this changed,” she said.

Out of desperation, she boarded a Yellow train to L’Enfant. From there, she would take an Orange or Silver train back to Virginia, eventually to Ballston. It was not a happy morning for her. “I watch TV,” she said, “but I wasn’t aware that it would affect this.”

Mary Hui, Josh Hicks, Michael Laris, Luz Lazo and Elise Schmelzer contributed to this report.