By the time the latest expansion of the Washington Metropolitan Area Transit Authority (WMATA) system, known locally as Metro and which opened in 1976, is completed in 2020, the system will serve 97 stations and operate on 188 kilometers (117 miles) of track on six interconnecting lines. Metro provides a critical transportation link to a population of approximately six million people within the 3,900-square-kilometer (1,500-square-mile) Washington Metropolitan area and has allowed job growth to expand to all corners of the region.

In the 1950s and 1960s, when the system was first conceived and construction began, most jobs were centered in downtown Washington, and most of the workforce commuted by bus or car. Today, transit-oriented development has increased residential, commercial and government facilities near most of the existing 91 stations, increasing the importance of the Metro system as a critical transportation link for the region. According to recent American Public Transportation Association (APTA) data, Metro is the second busiest transit system in the United States, after New York City’s transit system.

Brian Zelenko, Harald Cordes and William H. Hansmire co-authored "The Future of Transit Tunneling in Washington, D.C.," published in the June 2018 edition of Tunneling & Underground Construction. Zelenko presented the article at the North American Tunneling Conference on Tuesday, June 26 at 1:30 pm. View the complete article here.