Following eight years of construction, an extension is opening on the Washington, D.C., subway’s Silver Line, connecting the downtown of the nation's capital with the region’s largest airport for the first time and promising to spur development in burgeoning Northern Virginia.

Set to open Tuesday, the second phase of the Silver Line project adds 11 miles in Northern Virginia to a line that runs from Largo, Maryland, to Ashburn, Virginia. The line cuts through the center of D.C., and one of the new stops is Washington Dulles International Airport, which will join the Ronald Reagan Washington National Airport on a Metro line.

It comes as elected officials across the United States have been looking to encourage more building near public transportation to ease traffic congestion in fast-growing areas. Public rail usage, though, has been reduced by the pandemic, and for this line, lower ridership could translate to slower investment in the neighborhoods surrounding six new stops.

Even so, by connecting commuting areas and the heart of D.C., Metro has helped bring transit-oriented developments with millions of square feet of office and residential space to areas outside the city. Now, the additional stops push the Metro sytem farther into Virginia and creates more development potential.

“What it means for us is more work to do,” said Christopher Clemente, chairman and CEO of Comstock Holding Cos., a Reston, Virginia-based developer that’s heading several large-scale projects along the Silver Line.

Comstock began developing Reston Station at the Wiehle-Reston East stop, where the first phase of the Silver Line was completed in 2014. The 80-acre Reston Station is centered on the existing Metro station and will eventually include 6 million square feet of commercial and residential space, a third of which is already built, Clemente said. It’s now home to companies such as Google, Spotify, Rolls Royce and Comstock itself.

As the Silver Line neared completion, Comstock expanded its plans around other stations. It has also been joined by other developers.

Since 2014, "there’s been nearly 50 rezonings in Fairfax County between Tysons, Reston and Herndon, all brought about as a result of the Silver Line coming through the area,” Clemente told CoStar News.

These rezonings have paved the way for multifamily, office and industrial properties all along the Silver Line extension, which follows Route 267, also known as Dulles Toll Road. Similar to Comstock’s Reston Station at Wiehle-Reston East, Boston Properties is leading a 5 million-square-foot development anchored by the new Reston Town Center Metro station, which is the next stop. At another stop up the line, at the Herndon Metro entrance, Lerner Enterprises is planning a 1 million-square-foot development that was approved in August.

“The Silver Line is creating the kind of economic development that it was hoped to do,” Clemente said. “In time, the character of the Dulles Corridor will change from the low-rise and mid-rise buildings that were built many years ago at a much lower density to high-rise development.”

Comstock is also extending its plans along the line. In February, it filed plans with Fairfax County to develop 16 acres along the Silver Line between Sunset Hills Road and Sunrise Valley Drive. The plans call for six towers and 2 million square feet of development.

At the northern most stop of the Silver Line extension, Comstock also has Loudoun Station, a 3 million-square-foot development that is currently about half-finished. It centers on the Ashburn Metro station but has been in the works since 2013.

While developers are ready and raring to go, it’s been a long wait and the Metro’s promise might be somewhat dulled compared to what it was eight years ago. The Silver Line extension was originally scheduled to open in 2018 and suffered a number of delays, which could be attributed to various construction and regulation complications, a $1 million lawsuit regarding falsified testing of concrete panels and, most recently, supply chain and pandemic-related restrictions.

The Metro’s daily average ridership fell nearly 72% from 2019 to 2020 as COVID-19 kept people at home and essentially halted commuting, according to WMATA’s ridership database. Two years later, even as a chunk of the workforce has returned to the office, average ridership was at 219,000 per day in 2022, compared with 694,000 in 2014 when the Silver Line extension project began.

“I do think it’ll take a little while for it to get up to capacity,” said Clemente, adding that the offices at Reston Station are fully leased, but not fully used. “The companies are either hybrid or they have not come back to work. … I think that’s what’s going to keep [the Silver Line] from being an instant success.”

The line will bring workers and residents in Virginia to L’Enfante Plaza in the center of D.C., which connects with all the other Metro lines except the Red Line and currently has about 5,600 riders a day. The Silver Line also meets up with the Blue Line before getting to L’Enfante, which allows riders to travel south to Amazon’s planned second headquarters at National Landing and Reagan airport. Dulles airport, which is about 25 miles outside of D.C., will now be about an hour’s ride from L’Enfante Plaza.

Starting from the Silver Line’s former terminus at Wiehle-Reston East, the stations are: Reston Town Center, Herndon, Innovation Center, Washington Dulles International Airport, Loudoun Gateway and Ashburn.