Metro’s General Manager Paul J. Wiedefeld is set to announce on May 6 a massive overhaul of Metro’s rail system. (WUSA)

The commutes of hundreds of thousands of Washington-area residents will be upended when Metro General Manager Paul J. Wiedefeld on Friday unveils his long-awaited plan for a massive overhaul of the struggling rail system.

Wiedefeld will make the announcement at a mid-morning news conference at the agency’s downtown headquarters after he briefs Metro board members.

Although he declined to publicly disclose details of the plan before Friday, Wiedefeld said in an interview that the scope of the year-long maintenance overhaul will be unprecedented for the transit agency. He described it as painful medicine needed to cure subway infrastructure woes stemming from decades of maintenance neglect.

Much of that neglect, under previous generations of Metro leadership, resulted from public pressure to keep the subway operating at full capacity, for economic and convenience reasons. Wiedefeld, who became general manager in late November, has decided to impose months of aggravation on commuters in order to give work crews the time and space they need to restore the system’s long-lost safety and reliability.

“It’s definitely a significant change from the way that we’ve managed this in the past,” he said. “It’s going to take some sacrifice from all of us. But we have all seen how this has played out over the past few years, and that’s why I think the sacrifice is necessary.”

As if to underscore the point, officials on Thursday closed two stations and suspended service at four in the middle of the evening commute after a second smoke incident — this one caused by debris in the same area where an arcing insulator caused smoke and delays earlier in the day. Footage of that earlier incident — a dramatic explosion near the platform at Federal Center SW,  was caught on security cameras and widely circulated. 

In a memo this week to members of the region’s congressional delegation, Wiedefeld hinted that there will be major disruptions that will require not only patience from riders but cooperation from local governments and employers.

The plan is expected to impact all of the system’s lines, including weeks-long shutdowns of parts of lines, long-term single tracking and station closings. How much the effort will cost and how Metro will pay for it is still to be determined. A report from the Federal Transit Administration said Metro had a backlog of maintenance dating to at least 2012.

“The region will need to come together to provide traffic mitigation and alternative travel options to help reduce the impact on customers and businesses,” Wiedefeld wrote. “The business community has already offered support to identify major employers that will be impacted.”

He said Metro’s current service levels do not give crews enough time to complete the massive amount of work needed to restore the system.

“The hard truth is that 33 hours a week is not enough to dig out of the deferred maintenance hole, and at this rate, we will not reach an acceptable state of safety and reliability for several years,” Wiedefeld said in the memo to the delegation.

Wiedefeld’s plan will be the most ambitious effort ever to repair the aging system, which has suffered from years of neglect and inattention and a lack of a reliable funding stream. Wiedefeld said Metro’s past attempts to repair the system were too fragmented to truly address the system’s problems.

His announcement comes the same week that the National Transportation Safety Board released its report into the cause of the fatal 2015 smoke incident, which killed one train rider and sickened more than 90 others. Congress also said this week that it will hold its second oversight hearing in less than two months on the state of the Metro system.

The NTSB investigation into the fatal Yellow Line incident and examinations of at least a half-dozen other incidents that followed have painted a picture of an agency in turmoil — one that for years prioritized service over safety, failed to heed repeated warnings that it was putting its passengers and workers at risk and is now paying the price.

Wiedefeld has been tasked with turning around the 40-year-old system’s slide.

In just a few months on the job, the former airport chief and transportation executive has shown a willingness to take unpopular steps, even if it means angering riders and the officials who help fund his system.

In January, he shut down the entire system — bus, rail and MetroAccess — in anticipation of a massive snowstorm that blanketed the region.

And in March, after an electrical fire that bore eerie similarities to the deadly smoke calamity that led to the death of Carol Glover, 61, he took the unprecedented step of shutting down the entire subway for a day. The goal was to give crews time to conduct emergency inspections and repairs. Wiedefeld was criticized for not giving the public more notice, but he said that he couldn’t risk another death.

Wiedefeld this week also warned current employees of a coming staff shake-up.

He said that he sent a memo to more than 650 Metro managers, designating them at-will employees and “reminding them of our shared responsibility to properly lead this agency,”

Other systems have or are considering similar actions to repair damaged and aging infrastructure. New York’s Metropolitan Transit Agency is contemplating a plan that would shutter a subway tunnel between Manhattan and Brooklyn that runs under the East River, according to the New York Times. The L train tunnel was damaged by Hurricane Sandy, and officials concluded that they would be unable to make repairs during nights and weekends because of the complexity of the work.

The Chicago Transit Authority spent a year developing a plan to handle service before it shut down a portion of its subway system for five months in 2013. As part of that plan, it hired more than 400 bus drivers and added shuttles and new routes to areas affected by the closure. It also spent months educating riders about the shift. The closure affected nine stations.

Metro riders and regional officials won’t have a year to prepare, but Wiedefeld has pledged to be as transparent as possible about the anticipated effects.