Purple Line Tunnel Halfway Complete in Silver Spring

Transportation Secretary Pete Rahn tours Arliss Street site Tuesday

Maryland Transportation Secretary Pete Rahn, center, was on a tour of the Purple Line's Arliss Street tunnel construction site Tuesday. Dan Schere

The tunnel being built under Arliss Street in Silver Spring, part of the 16-mile planned light-rail Purple Line that will connect Montgomery and Prince George’s counties, is halfway complete.

Secretary of Transportation Pete Rahn and other state officials got a look at the tunnel construction during a tour Tuesday conducted by the Maryland Department of Transportation.

The tunnel is expected to be completed by 2020, said Nick Tabor, a project engineer with Traylor Bros., which is under the umbrella organization of the Purple Line Transit Partners, the public-private partnership building the light-rail line that will run from Bethesda to New Carollton. The line, which will have 21 stops, is expected to open in 2022. So far, about 500 feet of the 1,020-foot long tunnel have been dug. The tunnel is located 40 to 60 feet below the Long Branch neighborhood.

On Tuesday, crews were placing wire mesh on the walls of the tunnel as a reinforcement material.

Tabor said an average of 12 to 15 workers are at the site on a given day. Crews work 24 hours a day over six days each week, rain or shine.

The tunnel is adjacent to a Giant grocery store and close to residents who live along Arliss and Plymouth streets. The project has closed Arliss Street between Flower Avenue and Walden Road until 2020. Tabor said crews have attempted to minimize the effects of the construction by placing a sound wall outside the construction site and placing devices inside the tunnel that muffle the noise of the ventilation system, which typically generates 120 decibels of sound. Residents are also notified 24 hours in advance of any blasting, he said.

Purple Line Transit Partners spokesman John Undeland said so far neighbors have taken the construction in stride, but concerns about the project are understandable.

“We are doing our absolute best to have no surprises,” he said.

Dan Schere can be reached at Daniel.schere@bethesdamagazine.com