Photo by billkoplitz.

As you drive out of D.C. along I-66, massive concrete pillars that will soon support Metro’s Silver Line out to Tysons Corner and Reston—and eventually Dulles Airport and Loudoun County—rise from the ground.

Today, WTOP reports, the infrastructure for the Silver Line’s first phase made a huge leap, quite literally: a final segment of the 380-ton span that will carry trains over the Beltway was lowered into place:

The 380-ton span made up of 12 custom-cast concrete segments fits into place to complete the aerial guideway that will carry Metro subway trains through Tysons.

The first leg of the Silver Line, expected to open late next year, will have four stops in Tysons Corner.

In all, more than 2,700 reinforced, precast concrete segments, each weighing between 25 tons to 40 tons, have gone into the aerial structure.

Trains connecting the Orange Line out to Reston should begin running by December 2013, while Phase 2 extending out to Dulles and beyond should be ready by 2018.