Metro is boosting night bus service on 16th Street NW, one of the busiest corridors in the region’s bus system and a vitalone among late-night service workers.

The transit agency says that starting Dec. 31, limited-stop bus service will run until 9:30 p.m. on weekdays, a move to address crowding on the lines that serve 16th Street between downtown and Silver Spring .

The additional service on the limited-stop S9 would help ease the commute for workers whose shifts end after the traditional evening rush. But it would not aid the many service-industry workers whose shifts end between 10 p.m. and midnight, and who have endured crowded buses, unreliable timetables and long waits.

Metro officials say the additional two hours of S9 bus service on weekday nights will add 21 bus trips on the corridor, relieving congestion on the S2 and S4 buses. The schedules for the S2 and S4, which generally run between the Federal Triangle and Silver Spring Metro stations, will not change.

The new service will give riders an option for faster service from downtown to Silver Spring, Metro spokesman Dan Stessel said. The S9 serves limited stops between McPherson Square and the Silver Spring Metro station. It runs during the morning and evening rush hours. Under the new timetable, service will continue after 7 p.m. and run every 15 minutes in both directions — the last northbound trip leaving McPherson Square at 9:30 p.m.

This summer Metro made some improvements to the 16th Street bus lines after an article in The Washington Post highlighted the commuting struggles of janitors, restaurant employees and other low-wage workers who take the 16th Street bus routes after10 p.m.

Metro added longer buses to the lines and said it increased supervision of the routes to try to keep the buses on time and avoid bus bunching. Bus riders said they often waited more than 30 minutes for a bus. At some stops, buses would arrive too crowded to add passengers and would leave dozens of people behind.

“Our goal here is to expand service and provide more capacity for as many customers as possible,” Stessel said. “We are gratified that we can do that on the busy 16th Street corridor.”

He said the agency continues to study other options to improve service for night workers, but the agency is limited by its budget.

“We are always looking at ways to further improve service, and looking at additional capacity on 16th Street is part of the discussion,” he said.

The additional service is one of several changes in bus service going into effect at the end of the month, as part of Metro’s Better Bus initiative— a $5 million investment in service to improve on-time performance and reliability.

Another significant change is the launch of Maryland’s first limited-stop, or “MetroExtra ,” bus route. The K9 will serve New Hampshire Avenue between the Northwest Park Apartments in Montgomery County and the Fort Totten Metro station in the District. The K9 buses will run every 15 to 20 minutes during the morning and evening rush hours, and are also expected to address capacity issues in that corridor.