Former TTC CEO Andy Byford has stepped down as the head of New York City's bus and subway agency after two years on the job.

The Metropolitan Transportation Authority (MTA) made the announcement Thursday.

"Andy Byford will be departing New York City Transit after a successful two years of service and we thank him for his work," MTA Chairman and CEO Patrick Foye said in a statement. "Andy was instrumental in moving the system forward, enacting the successful Subway Action Plan and securing record capital funding with the Governor and the Legislature, and we wish him well in his next chapter."

Byford did not say why he was leaving, but there had been tensions, notably with New York Gov. Andrew Cuomo, who largely controls the MTA, the agency that includes the subways Byford oversaw.

Byford said in a statement he was grateful for the opportunity to head up North America's largest transit system.

"I'm very proud of what we have achieved as a team over the past two years and I believe New York City Transit is well-placed to continue its forward progress now that the MTA has a record breaking $51.5 billion Capital Program in place," he said.

Byford was the CEO of the TTC for five years prior to his move to New York in 2018.

According to the New York Daily News, the city's crumbling subway system has seen drastic improvements since Byford's arrival.

His departure comes three months after Byford issued a letter of resignation that he later rescinded, the newspaper reported.

Byford also picked up the nickname "train daddy" during his time in New York — something he eventually embraced.

NYCT President Andy Byford is out wishing customers a happy, healthy 2020, and thanking our Transit colleagues for their hard work tonight.<br><br>From Train Daddy himself: "Have a great night and get home safely! Mind the gap." <a href="https://t.co/KxUIEosB1u">pic.twitter.com/KxUIEosB1u</a> —@NYCTSubway

Crown Heights has some big Andy Byford fans <a href="https://t.co/LHCX9QFvRU">pic.twitter.com/LHCX9QFvRU</a> —@lizabeth_baker

When he started at the TTC in 2011, Byford said he realized the transit system needed to get back to basics. That realization led to a five-year plan introduced in 2013.

Byford said his achievements in Toronto included more reliable vehicles, a smart card system, modernization of the TTC fleet, 50 new streetcars and four-year contracts negotiated with TTC unions in 2014.

Originally from Plymouth, England, Byford came to the TTC from Sydney, Australia, where he was chief operating officer for Rail Corporation New South Wales.

Before that, he held several positions with rail operators in the United Kingdom, including general manager of customer service for several lines of the London Underground.

adam.carter@cbc.ca