The Americans with Disabilities Act (ADA) became law in 1990 and now, a quarter century later, the federal government—specifically the Federal Transit Administration—wants the 
to make more of its 469 subway stations accessible. The FTA has recommended adding more elevators, which could mean an additional $1.7 billion expense, according to the Wall Street Journal. Right now, only 22 percent of the stations are accessible. Compare that to San Francisco's BART system, which is 100 percent accessible (but has far fewer stations than the New York City subway), or Chicago's transit system, which has 145 stations, more than half of which are accessible. On top of that, the 's previous efforts at accessibility may have been a mistake. Instead of adding elevators throughout the subway system, which are both costly and complicated to install, the focused on making buses accessible (they all now accommodate wheelchairs) and adding paratransit automobile rides for the disabled. "It turns out that was a horrendously bad decision," Howard Roberts, who used to run NYC's transit system, told the WSJ. "It probably has turned out to be…100 times more expensive to go with buses and paratransit than it would have been to bite the bullet and simply rehabilitate the stations and put elevators in." Under the current plan, the number of stations with elevators will go from 111 to 144 by 2020, but the feds are pushing for more. WSJ reports there has been suggestion that subway station staircase repairs should be accompanied by elevator installation, a suggestion the has not taken kindly to. All of this makes the 's budget situation even more precarious, as the agency's slightly trimmed $26 billion capital plan is already in limbo.
Source: http://ny.curbed.com/archives/2016/02/01/nyc_subway_needs_17_billion_in_new_elevators_feds_say.php