Thomas F. Prendergast, the former head of the Long Island Rail Road and a three-decade veteran of public transit work, will begin as president of New York City Transit on Dec. 1. He replaces Howard H. Roberts Jr., who was forced out Wednesday after a change in leadership at the Metropolitan Transportation Authority.

Mr. Prendergast will be charged with carrying out the highest priorities on the ambitious agenda of Jay H. Walder, the authority's new chairman who has pledged a new era of transparency and innovation in the nation's biggest transit system.

Computer-chip enabled fare cards, G.P.S. devices in buses, and digital arrival-time clocks are among the new features Mr. Walder hopes to bring to the city's buses and subways.

Implementing those changes will be a prime responsibility of Mr. Prendergast, who is currently the chief executive of s TransLink in Vancouver, British Columbia, a position he has held since July 2008. The system oversees commuter rail, automobile traffic, buses, light rail, and bicycling in one of Canada's largest cities.

Mr. Prendergast formerly served as a top official at New York City Transit from 1990 to 1994, working under Alan F. Kiepper at a time when the system was still emerging from decades of neglect and decay. He began working in New York in 1982 and led the Long Island Rail Road from 1994 to 2000.

"Tom was a guy who had great operating experience, who knew how to make things work," said Peter Stangl, the former chairman of the transportation authority who appointed Mr. Prendergast to his position at the Long Island Rail Road.

Mr. Prendergast said in a statement: "Running New York City Transit is one of the great challenges and honors in the profession, and I will bring all of my energy and passion to the job."

"Tom is a leader who brings an extraordinary variety of experiences from around the world to a system that he already knows extremely well," Mr. Walder said in the same statement.