CHICAGO -- News that a dozen railroad spikes disappeared from a section of commuter rail highlighted a fear familiar to many train passengers: Sabotaging the tracks that crisscross the nation would be frighteningly simple.
Employees of the Metra suburban rail system discovered the damage Monday on Chicago's South Side, where the spikes normally hold down metal plates that bind the rails to wooden ties.
"The tracks themselves are generally open and unguarded," said David Heyman, director of the homeland security program at the Center for Strategic and International Studies, a Washington, D.C., think tank. "Thousands of miles of tracks are not fenced, and they're not watched."
Those tracks "remain vulnerable to anyone who wishes to do something malicious."
The FBI is investigating whether the tracks were sabotaged. A Federal Railroad Administration spokesman said if enough spikes were removed, the tracks could shift and cause a train to derail.
The United States has more than 140,000 miles of track that carry millions of rail passengers every year and scores of freight trains hauling hazardous materials. Potential sabotage also poses a risk to the untold number of people who live near tracks, experts say.
Some recent examples serve as reminders that trains are vulnerable.
In 2005, 11 people were killed and nearly 200 more injured when a train in Southern California derailed after plowing into an SUV that had been intentionally parked on the tracks. Ten years earlier, in the Arizona desert, one person was killed when a train ran into a dry stream bed after saboteurs yanked the spikes from the track.
"You need a good crowbar, a spike crowbar," and a strong person probably could do the job alone, said Robert Gallamore, who recently retired as the director of Northwestern University's transportation center.
What's more, experts say, trains are a favorite target for terrorists. Three years ago, train bombings in Madrid, Spain, killed 191 people and injured more than 1,800.
"All over the world, Spain, Columbia, Pakistan, India, Russia ... in the last 10 years there have been 200 incidents of terrorist attacks on train and rail," Heyman said.
At Chicago's Union Station, some passengers said they weren't concerned. But Leonard Webb worries - particularly when he thinks how easy it is to tamper with a train track in the middle of nowhere.
"All you have to do is know the train schedule (and) you would always know how long you have to do a job," said Webb, 24, as he waited to board a train to his Maryland home.
Steps are being taken - and more are in the planning stage - to beef up rail security. According to the Transportation Security Administration, about $110 million will be awarded to major rail systems this year.
Also, in 2005 the TSA added 100 rail inspectors, who are deployed around the country as part of a security inspection program, said TSA spokeswoman Lara Uselding.
But little is spent on railroad security, compared with the amount spent on air travel, said John Bentley of the Brotherhood of Local Engineers and Trainmen.
Even so, one train traveler in Chicago said he's against increasing rail security because he fears the costs will be passed on to passengers.
"We take (the train) because of the cost," said Gordon Schleicher, who was waiting to take a train back home to Michigan. "If you add to the cost, we wouldn't be able to take the train."