Blue Line riders had maybe the best T commute. Now, speed restrictions have trains crawling and riders bawling.

People rode a Blue Line subway train, Friday, March 24, 2023, in Boston.David L. Ryan/Globe Staff

The Blue Line, long considered by riders as the most reliable subway track in the MBTA system, has been hit hard by recent speed restrictions, with 77 percent of its tracks now covered by slow zones, according to T data released this week.

Trains that used to travel at 40 miles per hour for much of the stretch from downtown Boston to Revere now crawl between 10 and 25 miles per hour. MBTA travel time data analyzed by TransitMatters, a public transportation advocacy group, shows that a round trip on the Blue Line is now around 20 minutes slower than it would be if trains were traveling at full speed.

The dramatic changes have shocked and frustrated riders who shared their experiences of recent delays with the Globe on Friday.

Sophia, 15, is clear-eyed about the cascading impacts of new speed restrictions practically doubling commutes on the Blue Line. The delays, she said while waiting to board a train at Orient Heights Station, are causing fights between her parents.

“My dad makes dinner some nights, and so when he’s late and doesn’t make dinner, my mom gets mad,” said the teenager, who declined to provide her last name because she was not authorized to discuss her parents’ marriage.

She said her dad’s typical 30 to 45 minute commute home has started taking up to an hour.

“He’s always mentioning the delays are really inconvenient and are in the way of our schedule,” Sophia said.

Once the fastest and most dependable, the Blue Line now has more of its tracks covered by speed restrictions than any other MBTA subway line.

“I’ve taken the Green, Red, and Orange Line, and Blue was always the one that was on time and reliable,” said Exo Asmah, a 29-year-old rider getting off at Orient Heights. While she understood the MBTA’s rationale behind the speed restrictions, she said it was frustrating that longer trips could cause her to be late to work.

So how did the only subway line without any speed restrictions become this slow in just two months? So far the T has said very little.

On March 9, the agency slowed down the entire subway system to 25 miles per hour after its state oversight agency, the Department of Public Utilities, identified track defects on the Red Line that the T couldn’t account for. Since then, the agency has hired several consulting firms to review the results of machine inspections from February and March to make sure that all serious defects have corresponding restrictions.

MBTA spokesperson Joe Pesaturo and MassDOT spokesperson Jacqueline Goddard did not provide information Friday about whether the MBTA ever verified the machine inspections, the name of the person or firm the state is hiring to investigate the failure, or the number of serious track defects that the agency has discovered so far that did not have speed restrictions before March 9.

Last May, the MBTA shut down much of the Blue Line — from Bowdoin Station to Airport Station — for more than three weeks to replace the tracks, among other repairs. Now, that stretch of track in both directions is covered in speed restrictions related to track defects, the T’s slow zone dashboard shows.

Pesaturo and Goddard said the process of validating Blue Line defects found by machine tests is ongoing.

“While that validation process takes place to unequivocally determine the presence of any defect, speed restrictions remain in place as a precaution to continue the safe operation of Blue Line service,” the spokespeople said in a statement.

But as the agency sorts out its many issues, some riders are abandoning the trains.

Ryan Sherman recently switched to driving to work after his Blue Line commute got 10 to 15 minutes longer. On Friday, he was forced to take the subway because of an issue with his car and reminisced about better days.

“The Blue Line felt more reliable, and other lines were kind of iffy,” he said.

Now, the speed restrictions on the Blue Line tracks are some of the worst Frank Tino said he has ever experienced. The 82-year-old usually rides the Blue Line every week to get to Massachusetts General Hospital.

“I used to use it for school, I used it to go to work, I’ve used it all my life,” Tino said. “I totally disapprove of this. A ride that’s 10 minutes is now 30 minutes.”

Tino said restricting the speed of Blue Line trains makes it difficult for both elderly and young people who are trying to go to work or return home to their families.

Riders expressed their frustrations online as well, with many describing their slow commutes as “ridiculous,” “annoying,” and “absolutely destroying the morning commute.”

One rider, 34-year-old Alex Defronzo, even posted a video on Twitter showing himself outpacing the train on his bike on the East Boston Greenway.

Ouchie 👴 @MBTA @transitmatters pic.twitter.com/olyErg0oPP

— Alex D (@alex_defronzo) March 21, 2023

“I ride my bike home from work, and usually the train is going at full speed,” Defronzo said in an interview.

Sophia, the teen from East Boston, also said wait times between trains have increased due to how slow the Blue Line trains are. She said she usually waited around 5 minutes for the next train, but now has to wait at least 10 minutes.

“It was a lot faster to get to places, and you didn’t have to wait too long for the train, even if it’s the middle of the day on Thursday,” Sophia said.

Tino said the platforms are starting to get crowded as well because of how long it takes for a train to arrive, and it can make it difficult for many to hop onto already-full trains.

“Just imagine a mother with an infant going on the train,” Tino said. “If I had to speak with the person in charge of the MBTA, I would.”

Defronzo said it was particularly frustrating as the Blue Line serves communities with high populations of immigrants and frontline workers who use the T to get to downtown Boston.

“We’re lucky to have public transit, and [that’s] why I love living in East Boston,” Defronzo said. “But all of the suffering from decades of underinvestment and not giving the MBTA what it needs is frustrating.”