Officials in Alexandria are preparing for lengthy service disruptions on Metro’s Yellow Line that are expected to start in September.

The closures are due to two major construction and maintenance projects. Connecting the new Potomac Yard station to the current rail line will require a closure of all service south of National Airport from Sept. 10 – Oct. 6. Also starting in September, maintenance and rehabilitation on the Yellow Line’s bridge over the Potomac River and tunnel into D.C. will stop service between Pentagon station and L’Enfant Plaza for seven or eight months.

The Yellow Line is one of the primary rail links from Alexandria to the District. The last major shutdown on the line was in 2019, when Metro closed parts of the Blue and Yellow lines to restore the platforms on outdoor stations. Alexandria and Metro officials said Tuesday night that the 2019 experience — which featured its fair share of chaos and frustrated commuters — would inform their response this time around.

“These projects will have a significant impact on the community,” said Alexandria Mayor Justin Wilson. “The good news is that this is something that we’ve been through before, so we have some experience in what works.”

The City Council received a briefing on Tuesday night from city transportation staff and Metro leaders, which provides a first look at how Metro and the city will seek to mitigate the impacts of the service disruptions. The plans will be finalized in June.

A combination of buses and shortened Metrorail train routes will attempt to help riders navigate the system from Alexandria to D.C. during the fall and winter.

The most disruptive period will be in September and early October, when both closures — south of the airport and between the Pentagon and L’Enfant Plaza — will overlap.

During that time, Metro will run Blue Line trains from National Airport to Largo Town Center (the usual Blue Line route) as well as from National Airport to New Carrollton (the Blue Line route toward Largo Town Center, but shifting to the Orange Line after Stadium Armory and ending at the Orange line’s eastern terminus).

Metro will also run free local and express shuttle buses to replace closures, plus free downtown connector shuttles, airport shuttles, and other bus alternatives. The exact routes of those are yet to be determined.

For the rest of the time starting in October, the Pentagon to L’Enfant portion of the line will be closed, but the Yellow Line south of the airport will be open again, with Potomac Yard station newly open too, between the National Airport and Braddock Road stops.

During those months, the Yellow Line will be entirely closed, but additional Blue Line trains will operate from Huntington (usually the southern end of the Yellow line) to New Carrollton (the Orange Line’s eastern terminus), as well as on their usual route. Metro will also run a free downtown shuttle.

Alexandria officials are pushing Metro to add more trains to the standard Blue Line route, and to restore it on the 11Y bus line, a commuter express bus in to D.C. from the Mount Vernon area which was cut back during the pandemic.

“The one thing that even up to the very end of the [2019] shutdown I got complaints about was capacity on the 11Y,” said Mayor Justin Wilson. “That was a critical linkage for a lot of residents.”

Councilmember Sarah Bagley suggested Metro should consider bringing the service back permanently, not just during the coming shutdown. “Something we’ve observed throughout the pandemic is that bus ridership remained strong and has come back stronger,” she said.

Metro officials said they were still evaluating the options for bus service, including the 11Y route.

The looming shutdown comes at a highly uncertain time for Metro, which has been forced to sideline the 7000-series railcars that make up 60% of its rail fleet due to safety issues. This caused a severe cut to service at the exact moment the agency is trying to lure riders back two years into the pandemic.

“I think our ability to withstand this depends on you guys getting the 7000 series back,” said the mayor, who commutes by public transit to his day job at Amtrak. “We can’t further degrade the service. That’s just unacceptable.”

“You don’t do a major systemic upgrade when you’re not even running your service the way it’s supposed to run,” Wilson added.

Metro officials said they were working hard to get the cars operational. The agency recently had its plans to do so approved by the Washington Metrorail Safety Commission, the oversight group that initially ordered the trains to be removed from service.

But they made no promises of fast, dependable service during the shutdown. The presentation given to the City Council recommends adding an extra 15 minutes in travel time for the closure between Pentagon and L’Enfant stations — and it notes that train service may be even less frequent if the 7000-series railcars are not reintroduced to the system before then.

Wilson also had questions about Metro’s plan to run Yellow Line replacement trains along the Blue line route through the Rosslyn tunnel, a longtime bottleneck in the system where the Orange line, Silver line, and regular Blue line already converge to go into D.C.

Metro planners said they were looking at running each of the four lines — the Orange, Silver, Blue, and Yellow replacement trains — on 12-minute headways, which would translate to a slightly reduced volume compared to the number and frequency of trains running through Rosslyn before the pandemic.

The city of Alexandria is planning to implement other strategies to help people through the closures, including HOV lane conversions, city-provided bike classes, Capital Bikeshare programs, the Water Taxi, possible additional shuttle routes, and possible additional service from the Virginia Railway Express. All that is happening with help from the Virginia Department of Rail and Public Transportation, which is funding 80% of Alexandria’s costs on the project.

Alexandria Transportation and Environmental Services director Yon Lambert said he expects the city’s 20% share of the cost may run around $120,000.

In 2019, a key part of the city’s strategy to mitigate the impacts of the closure was running shuttles using its own DASH bus service. That won’t be the case this time, Lambert said, as DASH is already running more extensive, frequent service. But the buses could be deployed to help address issues in a small way this fall.

During the 2019 closure, 60% of people used the shuttle buses that replaced rail, 29% drove alone, 19% used Capital Bikeshare, 15% used the DASH bus, and 5% used water taxis, Lambert said.