Investigators say many people could have been killed because the train was carrying flammable liquid, which could have burned for a long time.
The incident prompted Amtrak to take additional security measures that are sure to be seen in Chicago.
The FBI is investigating an incident that someone tried to derail a 130-car train just west of Des Moines, Iowa.
On Sunday, train operators noticed a lock had been cut off a track switch box. Authorities say someone also created a two-inch gap in the tracks, and a black bag was used to cover the switch signal so tampering would be harder to notice. No trains were affected.
The incident is being looked at as criminal activity rather than terrorism. But Amtrak officials and federal authorities aren't taking any chances in the wake of recent terrorist threats against America's rail system mentioned in journals found in Osama bin Laden's compound after he was killed.
After meeting with Transportation Security Administration officials, Amtrak says it will expand its security. The new steps were announced Monday at a congressional hearing in Washington.
"There are layers of security that can be applied in the transit environment that reduce the vulnerability. And we're doing that by training our police officers and behavioral assessment, training our employees how to spot suspicious behavior and activity," said John O'Connor, VP and chief of police, Amtrak Police Dept.
Amtrak officials have used a variety of different security strategies. They have used high security fencing, blast curtains and technology-driven initiatives to protect stations, bridges and tunnels. Now, they are looking at expanding the use of those strategies for right of way protection. Amtrak says the threats are all still very real.