New York City subway chief makes resignation official

The chairman of New York City's Metropolitan Transportation Authority (MTA) Chairman officially announced his resignation Wednesday that is widely expected to be a precursor to a run for mayor of the city.

The MTA tweeted that its chairman, Joe Lhota, will be stepping down on Dec. 31 after a little more than a year on the job at the helm of the agency that runs the largest public transportation system in the U.S. The MTA said Lhota, who has run the the transit agency since November 2011, will be replaced by MTA Vice Chairman Fernando Ferrer on an interim basis.

Lhota is a former aide to New York City Mayor Rudy Guiliani (R). He is thought by New York political observers to be considering a run to replace outgoing New York Mayor Michael Bloomberg (I). 

Bloomberg has maintained a high national profile during his tenure as New York mayor. He is leaving office next year after serving a twelve-year term.

Lhota potential bid to replace him follows him winning widespread acclaim for swiftly restarting subway service in New York City after the system sustained widespread damage during Hurricane Sandy.

The New York subway system is the most extensive and heavily used transit system in the U.S. It carries more than 2 billion each year on 24 subway lines that cover 659 miles of track and service 468 stations.

By comparison, the second largest public transit system in the U.S. is Washington, D.C.'s Metrorail system, which carries more than 200 million passengers per year. The DC Metro system has 103 miles and 86 stations.