The 60-day probe, dubbed Operation Deep Dive, comes amid calls by two U.S. senators for expanded national railroad safety inspections.
Sen. Charles Schumer said safety inspections are "woefully underfunded" and that the FRA "simply doesn't have enough resources to fully inspect our rail lines, to sufficiently prepare implementation of safety measures or even do safety spot checks around the country."
The New York Democrat was joined by Sen. Richard Blumenthal, a Democrat from Connecticut, for a news conference at Grand Central Terminal, where the Metro-North train was headed before it crashed in Spuyten Duyvil in the Bronx.
More than 60 people were injured when the Metro-North train careened off the tracks as it approached a sharp curve. Federal investigators said the train was moving at 82 mph - more than twice the 30 mph speed limit at that point. The train engineer said he nodded at the controls, according to the investigators, his attorney and a union official.
Schumer and Blumenthal are asking Congress to meet the Obama administration's full request of $185 million for safety and operations for fiscal year 2014. That's an increase of about $15 million over this year's budget, which cut $9 million from the railroad administration.
The senators want the agency to hire at least 45 additional inspectors to bolster a staff of 347 devoted to safety. But the two Democrats say only 78 are actually checking tracks, and the government has only enough funds to inspect safety conditions, infrastructure and protocols at 1 percent of the nation's railroads.
"It's foolish to starve the nation's chief rail safety agency of resources," said Schumer.
Blumenthal said that, in general, "the Federal Railroad Administration has been AWOL on safety."
FRA spokesman Kevin Thompson said in a statement Sunday that the agency is committed to continuous safety improvements and that rail inspections are "one of many resources we rely on to ensure rail safety, including audits, reports, advancing risk reduction programs and furthering technology."
Thompson said 2012 was "the safest year in rail history" and accidents are down 43 percent over the past decade.
(Some information from the Associated Press)