Prior to his appointment supervising the transportation, urban development and public works of the city of Taipei, Huel-Sheng Tsay served as chairman and president of Taipei Rapid Transit Corporation for nine years. Under his leadership, Taipei Metro was ranked number one for system reliability among the 25 members of the NOVA and CoMET consortiums from 2004 to 2008.

Tsay is a former director general of the Taipei Water Department, which provides drinking water for the 4 million residents of the Taipei Metropolitan Area. With a specialty in directing policy for rapid transit systems and the computerization of traffic signal controls, metro operations and maintenance, he is often invited to deliver professional presentations at regional, national and international conferences.

Tsay holds the Past President Award from the Institute of Transportation Engineers (ITE) and the Annual Transportation Medal from the Chinese Institute of Transportation. He was chairman of the Nova International Railway Benchmarking Group from 2006 to 2007, and vice chairman of the Asia-Pacific Division of the International Association of Public Transportation from 2002 to 2010. He has authored books and more than 50 papers in journals and conferences. He received the 1990 Best Book Award of the Chia-Hsin Cultural Foundation for his book, Theory and Applications of Traffic Control.

Tsay is a professor at National Taiwan University of Science and Technology and an active member of several professional associations.