The F train, which runs between Brooklyn and Queens by way of Manhattan, was headed into Manhattan when six of its eight cars left the tracks near 65th Street and Broadway.
Nineteen people were hurt, four of whom were taken to the hospital with more serious injuries.
The area where the train derailed was labeled a "critical rail break" corridor by the MTA and was scheduled for replacement in the future. Between 2005 and 2012, there had been 205 broken rails between 50th Street and 71st Street/Continental Avenue on the line. That the second-highest concentration of rail breaks of the entire subway system, the New York Daily News reported.
The line of track and four other areas were slated for a multimillion-dollar replacement project set to begin in 2015 at the earliest. The existing rails, which are bolted together, would instead be welded together for greater strength.
“You have got to ask about this near rush-hour derailment on one of the busiest lines in the subways: Are transit officials replacing track fast enough and in the right places?” said Gene Russianoff, executive director of the Straphangers Campaign, an advocacy group. “We look to the national and state safety monitors to get us independent answers.”
The cause of the derailment is under investigation, though it's believed defective rails were to blame.