The Washington, D.C., Metro subway system will stick to a planned reopening at 5 a.m. Thursday after an unprecedented 29-hour system-wide shutdown for emergency repairs that caused headaches for hundreds of thousands of commuters, the agency's general manager said Wednesday evening.

Capital-area highways were clogged with bumper-to-bumper traffic during rush hour Wednesday, inconveniencing hundreds of thousands of people, ranging from commuters to students.

The shutdown was announced so construction teams could make urgent inspections of electrical components.

"Before 5 a.m., we will finish the immediate repairs for all zones. We will open the system at 5 a.m.," Metro general manager Paul Wiederfeld said at an evening press conference.

In the event further issues were found overnight, Wiederfeld said the agency would institute single-tracking or bus shuttles localized to the area of attention.

Crews working underground since late Tuesday night found 26 areas where damaged "jumper cable" and "connector boot" electrical elements were found. 

The drastic actions were taken in the wake of two major equipment-related incidents in the underground.

One woman was killed and dozens sickened in 2015 after smoke from an electrical malfunction filled a train car at the busy L'Enfant Plaza station. On Monday, an electrical fire involving the same type of component as the 2015 incident stymied morning rush hour train traffic at the McPherson Square station near the White House.

Throughout the day, crews also came across three of what Wiederfeld called "showstoppers," or problems that would have required immediate attention if they were found on an average day.

Earlier Tuesday, Wiedefeld said the closure was necessary to ensure rider safety.

"While the risk to the public is very low, I cannot rule out a potential life and safety issue here, and this is why we must take this action immediately," he said.

Roads were even busier than usual during rush hour. District Department of Transportation Deputy Director Greer Gillis told The Associated Press that she was seeing heavier-than-normal volume, particularly traffic coming from Maryland. She expects more traffic and a longer-than-usual rush hour, but traffic was still flowing.

Highways into Washington from northern Virginia also were more choked with traffic than a normal weekday, with bumper-to-bumper traffic on interstates 95, 295 and 395. Drivers with navigation apps avoided some of the highways and snaked slowly through the narrow streets of Old Town Alexandria and the Crystal City commercial district.

Even while avoiding the worst traffic, the 18-mile drive from Springfield, Virginia, to Washington's Union Station took about 90 minutes, and some downtown parking garages were full.

The federal government encouraged employees to take the day off or telecommute, children were allowed to miss school and some workers woke up early to take bus after bus, hail pricey taxis or slog through traffic, resigning themselves to a long day.

Michaun Jordan, 51, usually takes a commuter train, then Metro rail lines and a bus to get to her job as a finance officer for the federal government. But on Wednesday, she took a $15 taxi after her train, then waited at Rosslyn station in Virginia for a bus.

"At first I was a bit disappointed. Then I thought about it — it's best to be safe," she said.

The nation's second-busiest transit system was shut down at midnight Tuesday for a system-wide safety inspection of its third-rail power cables, prompted by a series of electrical fires. It will reopen at 5 a.m. Thursday unless inspectors find an immediate threat to passenger safety, which the system's general manager said was unlikely.

Ridership on Metro has dipped as the system's reliability has deteriorated, and gripes on social media occur daily.

Still, riders take more than 700,000 trips on Metro trains every day because it's still the best way to get downtown from Maryland, Virginia and the city's outer neighborhoods. On Wednesday, they didn't have that option.

"It's always slow, always crowded," Bob Jones, 26, of Arlington, Virginia, said of Metro.

But on Wednesday, as he waited for his normal bus to work but planned a walk of more than an hour home without his usual option of the subway, he said he wasn't too upset with the decision to close.

"Better that than, like, a fiery inferno," he said.

Lester Broughton, 71, and Glorious Broughton, 68, spent the night at Ronald Reagan Washington National Airport rather than risk missing their Wednesday flight to Florida. They usually take Metro and considered Uber, a taxi or SuperShuttle but thought that could be expensive or crowded.

"I would've preferred to sleep in my bed last night," Glorious Broughton said. But she said she believes in the Serenity Prayer, which says "God, grant me the serenity to accept the things I cannot change."

Despite the announcement Tuesday, not all would-be Metro riders got the message that the system would close. At Metro's Rosslyn station in Virginia, just over the Potomac River from Washington, Derya Demirci, 27, looked disbelievingly at a sign announcing the shutdown. She had hoped to take her normal train to her childcare job.

"I don't know what to do," she said. She settled on taking a picture of the sign ("Your safety is our highest priority," it read in part) and asked her husband to drive her to work.

Metro wasn't yet hearing reports of overcrowding on buses, spokeswoman Morgan Dye said by phone Wednesday morning. But many people were planning several buses instead of their usual, easy subway rides.

"I've got to catch five buses to get to Alexandria," Leander Talley, 52, said. "... It's like three and a half hours. It's crazy."

Talley then loaded his bicycle onto a bus on the Springfield Metro station. It's normally one of the busiest in northern Virginia, but the massive parking garage — where parking was free Wednesday — was mostly empty, and only a handful of people waited for buses at 7:45 a.m.

On Monday, a fire on the Metro rail tracks led to major delays throughout the system. The fire was caused by the same kind of electrical component that malfunctioned last year and caused a train to fill with smoke inside a downtown Washington tunnel, killing one passenger and sickening dozens.

D.C. Council member Jack Evans, the chairman of Metro's board, said that while the system had previously been closed for days for weather, including earlier this year, Wednesday was believed to be the first time the system would be shut down for mechanical reasons.

U.S. Transportation Secretary Anthony Foxx said in a statement that putting safety first is the right choice but Metro needs to get serious about fixing issues.

"I've said it before, and I'll keep saying it until the region takes real ownership of its safety oversight responsibilities: D.C., Maryland and Virginia need to stand up a permanent Metro safety office with real teeth. What are folks waiting for?" Foxx said.

Late Wednesday, Sen. Barbara Mikulski, D-Md., called for an oversight meeting between Virginia and Maryland senators and Metro officials.

News of the closure exploded on social media, with some on Twitter dubbing the situation "#Metromageddon" or "#Metropocalypse."

Another population affected by the closure: students at the District's public schools. The city does not have traditional school buses and many students rely on Metro, which they are allowed to ride for free, to get to school. The school system announced that while schools would be open, absences and tardiness would be excused. D.C. Council member David Grosso said he was concerned about student safety.

"This is a significant disruption for many of our families," Grosso said.

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The Associated Press contributed to this report.