CHICAGO (CBS) – Amtrak has enhanced its security ahead of the 9/11 anniversary and officials say that, over the past decade, they’ve transformed their police force from a unit that largely responds to crime to one that anticipates it.

CBS 2′s Mike Puccinelli reports on how they are doing that with the help of highly trained dogs capable of checking hundreds of people almost simultaneously.

Officer Nick Vergis strapped phony C-4 plastic explosives to his ankle on Wednesday to show how the Amtrak Police K-9 units can find explosives by smell alone.

If it were real, the bomb belt used in the demonstration would be enough to take down a good portion of Union Station in Chicago.

K-9 trainer Alan Janda said a bomb that size could cause severe damage and take many lives, “without a doubt.”

But the portable bomb used in Wednesday’s demonstration only smells like the real thing.

Vergis wore it because he was putting Amtrak police dog Rider to the test. The Labrador Retriever is a “vapor wake” dog trained to smell vapors from explosives hidden on people who are moving. And in a busy train station, it’s important to allow people to move freely.

“We do this in a way that doesn’t cause you to take off your shoes and line up to get on each train,” Amtrak spokesman Marc Magliari said. “But still, you’re being checked and you’re being checked with these specially trained animals.”

In the past, most dogs were trained to smell explosives in packages and stationary objects hidden in areas, like under a bench. But vapor wake dogs can detect scents left in the wake of a passing suicide bomb or terrorist.

When Vergis walked into the Great Hall at Union Station, it didn’t take long for Rider to key in on him.

“He actually got the decoy before he came through the doors,” Amtrak Police Sgt. Mike Stoltz said. “He started showing change in behavior and stepping up his search and he got him before he came in the doors.”

While the dogs have been in use at Amtrak in Chicago for about a year, they are not in use at O’Hare International Airport.

“It doesn’t surprise me, because I haven’t seen them anywhere except when I leave the country. They have them at the airports in other countries,” said O’Hare traveler Tammy Shelley.

Amtrak uses the dogs, in part, to keep things moving. At O’Hare, security officials use dogs, but not vapor wake dogs. Many passengers at O’Hare said they’d welcome vapor wake dogs if they would speed up check-in times.

Transportation Security Administration officials said that three K-9 teams in the Chicago area are in the process of being trained and certified as “vapor wake” dogs. As soon as the training is completed, those dogs will be deployed at O’Hare. The date has yet to be determined.