That's almost entirely just to pay the interest on the debt, they're not actually trying to reduce the debt itself.
See the first NYT article:
> Every second of every day, the M.T.A. pays $83 in interest. That’s $7.1 million in 24 hours; for the year, a total of $2.603 billion. Those costs consume 16 percent of the transit agency’s budget, nearly three times as much as in 2002, according to the state comptroller, Thomas P. DiNapoli.
See the first NYT article:
> Every second of every day, the M.T.A. pays $83 in interest. That’s $7.1 million in 24 hours; for the year, a total of $2.603 billion. Those costs consume 16 percent of the transit agency’s budget, nearly three times as much as in 2002, according to the state comptroller, Thomas P. DiNapoli.
https://mobile.nytimes.com/2017/11/16/nyregion/subway-new-yo...