The Metro tunnel beneath Tysons Corner in September. (Nikki Kahn/The Washington Post)

The Dulles Metrorail project announced that the ramp from westbound Route 7 to southbound Route 123 is back in service as of today.

The ramp was closed in September 2010 to create a work zone on the west side of the short tunnel that will link the portion of the new rail line being built on the north side of Route 123 and the portion under construction along the median of Route 7. The grade would have been too steep to allow the trains to run on the surface in that area.

When completed in 2013, the new Metrorail route, known as the Silver Line, will connect Reston with the rest of the rail system via Tysons Corner. A second segment will eventually extend to Dulles International Airport and Loudoun County.