The TWU's three-year contract with the MTA, which covers about 38, 000 workers on the city's bus and subway system, expired on Sunday.

WSJ: Union Terms MTA Tactics 'An Outrage'

TWU, meanwhile, knew the US Airways management team because it represented workers at both America West and US Airways, which merged in 2005.

FORBES: How Labor Made US Airways, AMR Merger Happen

Because it's illegal for public employee unions in New York state to strike, the 2005 work stoppage led to a range of sanctions from which the TWU is still recovering.

WSJ: Union Terms MTA Tactics 'An Outrage'

In fact, last year TWU Local 100 ran a YouTube video noting that for every rat subway riders saw, there were 8-10 more in hidden areas throughout the subway system.

FORBES: UPDATED: Rat Invasion? Will Subway Rodents Move Into Flooded NYC Neighborhoods?

Recent TWU contracts have been for five years.

WSJ: Union Terms MTA Tactics 'An Outrage'