Commuters make their way to and from the free shuttle buses at the Twinbrook Metro station on Saturday in Rockville. The Shady Grove and Rockville stations are closed because of SafeTrack work on the Red line. (Salwan Georges/The Washington Post)

As Metro’s final SafeTrack surge gets underway on the western end of the Red Line, regional leaders are tempering their celebrations with warnings that the embattled transit agency faces even more challenges in coming months.

Years of flagging ridership show no signs of an immediate turnaround. Political infighting over the prospect of a dedicated long-term revenue source threatens to send the agency into financial tumult next year.

And though the track overhaul program branded as SafeTrack officially wraps up with the surge beginning Saturday, Metro is already making plans for three more disruptive maintenance projects to take place over the next year.

“We have more work to do,” Montgomery County Council President Roger Berliner (D-Potomac-Bethesda) concluded Thursday as officials gathered to kick off the 16th and final surge.

But though the next year for Metro will probably be no easier than the last, General Manager Paul J. Wiedefeld says he is confident that the system is much safer today than it was more than a year ago, when chronic safety issues with the tracks prompted him to launch the intensive year-long maintenance program aimed at cramming three years of critical repair work into one.

“Put it this way,” Wiedefeld said earlier this month. “I’m sleeping a lot better now because I know the improvements that we’ve made.”

And though SafeTrack disruptions had a dramatic impact on the lives of the region’s Metro riders — many of whom have abandoned the system, exasperated with weeks of nonstop single-tracking on top of unexpected daily delays and breakdowns — Wiedefeld said he knows SafeTrack had one positive effect on the region. Now, he said, no one can say they are not aware of the urgency and magnitude of the agency’s problems.

“You see it internally. You see it at [Metropolitan Washington Council of Governments] meetings. You see it at board meetings. You see it in D.C., Richmond and Annapolis,” Wiedefeld said. “There’s nobody that’s saying, ‘No, we’re not going to deal with this,’ or ‘It’s not as bad as we thought.’ None of that. You don’t hear that anymore.”

Standing outside the Twinbrook Metro station Thursday, Metro Board Chairman Jack Evans was careful not to venture too far into celebratory tones. Recently, he’s taken to quoting Winston Churchill, describing SafeTrack’s closing salvo as “the end of the beginning.” But despite the looming problems, Evans said riders should cheer the completion of the program, which allowed Metro crews to replace more than 50,000 wooden rail ties and overhaul the 20 percent of the tracks in worst shape — at a cost of $150 million.

“For so long, Metro has been criticized for not doing what it was supposed to do,” Evans said. “Our workers worked overtime, they worked on nights, to get three years’ worth of work done in one year . . . for an organization that is roundly criticized as not being able to do anything.”

But SafeTrack is not over yet. Surge No. 16 began Saturday and is scheduled to last nine days. During that time, the Shady Grove and Rockville stations will be closed, with bus shuttles replacing rail service on the five-mile segment between Shady Grove and Twinbrook.

Metro recommends riders who normally use Shady Grove or Rockville consider starting their trip at Twinbrook, White Flint, Glenmont or Wheaton during the surge.

The same stretch of the Red Line was closed for 13 days in August during Surge No. 7, but Metro work crews managed to complete only 86 percent of the scheduled track work. Officials said workers were forced to proceed more slowly because of extreme heat and electrical storms. Now, they’re hoping to finish what was left off, and more.

“We learned things along the way,” Wiedefeld said, “and there were things we had to get back here and get on top of.”

As a result, Metro officials say they expect a 25 percent reduction in the frequency of service on the remainder of the Red Line. Typical rush-hour headways will be eight minutes, rather than the usual six minutes.

Closer to the core, between the ­Grosvenor-Strathmore and Silver Spring stations, the peak-period wait for trains will lengthen from three minutes to four minutes during the surge.

Metro says service should remain near normal on all other lines.

There will be express bus shuttles traveling directly between Shady Grove and Grosvenor-Strathmore stations during weekday peak periods, from 5 to 9:30 a.m. and 3 to 7:30 p.m.

There are also a slew of regular bus options for riders seeking to avoid the shuttles: The Q1, Q2, Q5 and Q6 all make stops at Shady Grove and Rockville before traveling to the Silver Spring station on the opposite end of the Red line. The T2 travels from Rockville to Friendship Heights, and the C4 starts at Twinbrook station and culminates at Prince George’s Plaza station.

Montgomery County’s RideOn service also serves the affected stations on routes 46 and 55. Riders may also opt to pick up the MARC train at Rockville station.

But mostly, transportation officials are hoping that Metro’s final surge comes to pass with little drama and few disruptions.

“We want our community to make the alternative arrangements, get on MARC, get on RideOn, get on all the alternatives you need to get to work on time,” Berliner said. “And then this piece hopefully will be over, and then we will get to work on the rest.”

Still, there may be commuting headaches, according to Lei Zhang, director of the University of Maryland’s National Transportation Center and a professor of civil and environmental engineering. Zhang and his team have been studying the traffic and congestion impacts of SafeTrack since Surge No. 1. Though the need for advanced planning and flexibility should not come as a surprise to experienced commuters after more than a year of SafeTrack, he warned that Montgomery County residents should not become complacent.

His advice: Avoid potential overcrowding at the Twinbrook parking lot, and travel further toward the center of the Red line before hunting down a parking spot and jumping on the train.

Zhang also warned that the most dramatic impact on traffic on Interstate 270 during the surge will probably come between 6 and 7 a.m., as routine drivers and displaced Metro riders opt to hit the roads early in an attempt to beat the traffic.

“Everybody tries to game the system by leaving a little early,” which only serves to hasten the gridlock, Zhang said. “The early birds should pay attention to this one and maybe even leave earlier than usual.”

One mitigating factor: Surge No. 16 began the day after the last day of school in Montgomery County.

“That certainly helps,” Zhang said.

But whether the disruptions are minor or Surge No. 16 goes out with a bang of traffic and chaos, Zhang and other researchers at the National Transportation Center will be taking careful notes. Over the 13 months of SafeTrack, they have amassed a huge set of data and observations about transportation network resiliency and the impact of transit disruptions on a dense urban area — research that will be shared with other scientists around the world.

SafeTrack, and the sacrifices made by the region’s riders, have made immense contributions to engineers’ and planners’ knowledge, Zhang said. Still, he’s not sad that it’s coming to an end.

“We’re not worried,” Zhang said. “We’re sure there will be some kind of service disruption that happens on Metro again.”