Last Sunday, someone tried to derail a train carrying highly flammable ethanol in the town of Menlo, Iowa.
Officials said someone intentionally tampered with a track switchbox and gapped the track by two inches in hopes of causing derailment and possibly a collision. Fortunately, crew members with Union Pacific noticed the abnormality and notified authorities in time.
The close call has yet to be tied to a terror group but materials found at Osama bin Laden's compound provide evidence that U.S. trains and subways are likely terror targets.
"We are very concerned about the recent events and we will continue to work with the federal government to do all we can to protect America's rails," Amtrak Police Chief John O'Connor said while testifying on Capitol Hill this week.
He said they have expanded patrols and bolstered security along thousands of miles of roadway to increase right-of-way protection.
While there have been no known threats in Los Angeles recently, the L.A. County Sheriff's Department says it's staying vigilant, and commuters are taking notice.
"I see a lot of the anti-terrorist police that are involved...but I see them as a welcomed presence, and I feel safe," said Gordon Carle of Burbank.
But officials say vigilance on the commuter's part is just as important. They continue to encourage riders to come forward if they see anything suspicious.