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Metal panels dampen train noise

Metal roof panels were installed on an acoustically designed sound cover box to reduce wheel squeal noise from trains on a portion of loop track during phase one of the Dulles Corridor Metrorail Project, completed in 2014.Metal roof panels were installed on an acoustically designed sound cover box to reduce wheel squeal noise from trains on a portion of loop track during phase one of the Dulles Corridor Metrorail Project, completed in 2014. The project includes a new 23-mile Metrorail line that extends service from the existing Orange Line at East Falls Church station in Fairfax County, Va., to Route 772/Ryan Road in Loudoun County, Va.

The 1,096-foot-long sound cover box's envelope consists entirely of metal panels. It was clad with Englert Inc.'s 22-gauge Galvalume Series 1300 mechanically seamed roof system. Of the 850 total panels, 722 are tapered and 128 are straight; the longest tapered panel is 84 feet. The straight panels were installed on top of eight 24-foot by 27-foot penthouses. Most of the panels were rollformed on-site and the remainder at Englert. Seam spacing is 20 inches wide at the eave and the roof slope is 1/8:12.

The inside and outside walls of the sound cover box curve follow the rail tracks. The first segment of the structure has exterior walls constructed to curve on arcs laid out with two different center points. All 200 panels in this section have different tapers and lengths. Additionally, Englert's Metalman HT-60 Underlayment with a 3-inch Rigid Insulation Board was mechanically fastened to the steel deck.

The Dulles Corridor Metrorail Project includes five new stations and improvements to the existing West Falls Church Yard. The expanded facilities at West Falls Church Yard are intended to provide operational support of the Silver Line Metrorail extension to Washington Dulles International Airport and Loudoun County. The yard connects to the Silver Line tracks via a tunnel running under the eastbound lanes of the Dulles Access Road extension to a surface portal in the median.

Owner: Metropolitan Washington Airports Authority, Washington, D.C.
Design-builder: Dulles Transit Partners LLC, Vienna, Va.
Metal roof panels/underlayment: Englert Inc., Perth Amboy, N.J., www.englertinc.com