Safety officials have supported what's known as positive train control technology for decades, but the railroad industry has postponed installing it due to the high cost and technological issues.
The train was traveling at 82 mph as it entered a 30 mph turn Sunday morning and ran off the track, according to the National Transportation Safety Board member Earl Weener. Four people were killed and more than 60 others were injured.
Investigators have not determined whether the wreck was the result of human error or mechanical trouble. However, some safety experts say the tragedy might not have happened if Metro-North Railroad had the technology, and a lawmaker said the derailment underscored the need for it.
"This incident, if anything, heightens the importance of additional safety measures, like that one," said U.S. Sen. Richard Blumenthal, a Democrat from Connecticut, which also is served by Metro-North. "I'd be very loath to be more flexible or grant more time."
The New York Police Department is conducting its own investigation with assistance from the Bronx district attorney's office in the event the derailment becomes a criminal case.
Weener said it's possible that the throttle was let up and the brakes were fully applied way too late to prevent the crash.
He said the throttle went to idle six seconds before the derailed train came to a complete stop - "very late in the game" for a train going that fast - and the brakes were fully engaged five seconds before the train stopped.
It takes about a quarter-mile to a half-mile to stop a train going 82 mph, according to Kevin Thompson, a Federal Railroad Administration spokesman.
Investigators are not aware of any problems with the brakes during the nine stops the train made before the derailment.
Weener did not disclose what investigators know about the engineer's version of events, and he said the results of drug and alcohol tests were not yet available. Investigators are also examining the engineer's cellphone; engineers are allowed to carry cellphones but prohibited from using them during a train's run.
Positive train control, or PTC, is designed to forestall the human errors that cause about 40 percent of train accidents, and uses GPS, wireless radio and computers to monitor trains and stop them from colliding, derailing or going the wrong way. The transportation safety board has urged railroads to install PTC in some form since 1970, and after a 2005 head-on collision killed 25 people near Los Angeles, Congress in 2008 ordered rail lines to adopt the technology by December 2015.
Metro-North has taken steps toward acquiring it but, like many rail lines, has advocated for a few more years to implement a costly system that railroads say presents technological and other hurdles.
The Associated Press contributed to this report.