Metrorail testing may sound like small explosion

Contractors working on a Metrorail extension in Virginia will conduct testing that may sound like a small explosion.

Contractors working on the Dulles Metrorail Project are planning to test the structural integrity of a support pillar on Thursday around 1 p.m., weather permitting. The location of the test is near the interchange between Dolley Madison Boulevard and the Dulles Toll Road.

The test is routine and will be used to gather data about the load capacity of caissons, the foundations of the piers that will support aboveground tracks.

The first phase of the Metrorail extension, which will eventually go out to Dulles International Airport, is expected to be completed in 2013.