Metro officials are making an aggressive push to repair the transit system’s rails and stations, and this weekend four stations will be closed through Memorial Day so crews can work around the clock.

The shutdowns are an extreme Metro has used with more frequency to catch up on a backlog of repairs and maintenance across the aging rail network, much of which turned 35 this year.

Metro has launched a $5 billion capital improvement effort, but it leaves riders with late-night delays and longer weekend waits.

“The system wasn’t maintained the way it should be, and we have to make up for that now,” said Richard Sarles, Metro’s general manager and chief executive. “That’s why we’re doing this intensive work.”

Overall plans call for replacing ventilation and exhaust fans; repairing platforms; redoing elevators, escalators and tiles at stations; fixing cracks in tunnels; and repairing signals, circuits and equipment along tracks.

Unlike other systems, which have multiple tracks and can often isolate their work, Metro has only two tracks, so it often has to do single-tracking to complete work. At times, it’s easiest to shut down stations on weekends to do the more complex jobs, officials said. Metrorail registers about 750,000 rider trips on weekdays, but the number drops by more than half on weekends.

Crews also work three-day weekends because it allows them more time to move heavy equipment into stations, officials said.

This weekend, more than 1,100 Metro employees and contractors are scheduled to work on repairs and maintenance. Metro is shutting down four stations on the Orange Line, including the one closest to RFK Stadium, which is the site of a four-day motorcycle festival.

The closure of Capitol South, Eastern Market, Potomac Avenue and Stadium-Armory stations will also affect access to restaurants, hotels, monuments and other Memorial Day weekend attractions. Metro is offering free bus shuttles for riders to navigate among the closed stations.

Officials said Metro is also trying to move faster on implementing recommendations from the National Transportation Safety Board, which has sharply criticized the system for its poor safety record.

Last year, the investigative agency said Metro wasn’t moving fast enough on replacing some track switches, which guide trains from one track to another. Metro officials promised to replace 178 switches by the middle of 2012. Crews have completed 148. To meet the goal, Sarles said, “requires us to take advantage of every one of these three-day weekends.”

Work delays riders

Doing the work is no easy task.

“You have to go in the tunnels, disconnect everything, bring in cranes, take out all the electrical, all the switches, put in a new set of equipment and put it all back in, plus get it tested” all between the Friday night shutdown and the system’s opening Tuesday, Sarles said.

“We’re trying to meet the safety recommendations, and we’re trying to get this operation back to where it operates reliably and it is more comfortable,” he said.

For riders, weekend work has meant more headaches.

Michelle McHugh, 44, of Houston abandoned her plans Saturday to take Metro to Reagan National Airport for a flight home. Instead, she caught the Red Line from Grosvenor-Strathmore to Woodley Park, where she was meeting friends for a quick meal. Afterward, she planned to take a cab to the airport.

“I’m worried about the train delays,” she said as she waited at the Grosvenor stop, glancing at her watch and at the signs above the platform that warned of potential delays because of track work.

Nearby at the Grosvenor platform, Serena Welch of Bethesda waited with a friend for a downtown-bound train to take them to a fundraiser.

“We hadn’t planned to wait 14 minutes,” Welch said as she looked at her watch.

Her friend, Caroline Rushby of Gaithersburg, said: “Metro used to be the best thing to have, especially on weekends, because you didn’t have to spend so much on gas. But now weekends are becoming the worst. It can take up to three hours to get somewhere because of the delays.”

Rushby and Welch gave up after waiting 30 minutes. They said the screens on the platform went blank, and then the screens said only one line was working. The pair hailed a cab and paid $32 to get to their destination.

An issue for rail systems

Metro is not alone in trying to find the time to squeeze in its repair work.

In San Francisco, the Bay Area Rapid Transit agency (BART) has up to $20 billion worth of capital improvement projects underway to improve its nearly 40-year-old system. BART, which does about 350,000 daily rider trips, conducts evening and weekend shutdowns on some of its rail services to allow crews enough time to do the work.

“By the time you shut down the power, get all the clearances done, get crews in there and be safe while doing it, you’ve got about an hour of actual wrench time to do work during the week and about three hours on weekends,” said Jim Allison, a BART spokesman.

Over Memorial Day, BART plans to shut down one of its tracks, connecting Oakland to San Francisco, so crews can do electrical work along the line. Some riders will probably have to wait an extra 20 to 40 minutes for trains, officials said.

New York City’s subway, which does 5.3 million rider trips each weekday, faces difficult challenges in maintaining and upgrading its 100-year-old subway system because it operates 24 hours a day, seven days a week. The system is in the second year of a $23.8 billion, five-year capital improvement plan. Over Memorial Day weekend, 17 of its 26 train lines will be affected by work.

“There’s a level of frustration by riders, but they also understand that this work is essential to maintain our infrastructure and upgrade our signals,” said Kevin Ortiz, a spokesman for New York’s Metropolitan Transportation Authority. “A system in disrepair that transports more than 5 million riders daily is simply not an option.”

In the Washington area, the weekend shutdowns will continue beyond Memorial Day, Metro officials said. Work is planned for the first weekend of June and over the Labor Day weekend. On the Saturday and Sunday of the Fourth of July weekend, work will occur outside the downtown core that will require single-tracking.

Sarles said the capital work is “going to go on for years.”

“We’re taking the worst right now and moving from there,” he said, “but we’ll have to continue to make improvements.”