ELMSFORD, N.Y. (CBSNewYork) — A wrong-way disaster was averted in Westchester County on Monday when a roadside emergency truck driver took quick action.

As CBS2’s Lou Young reported exclusively, the actions by the truck driver on Interstate 287 in Elmsford made the difference between a potential tragedy and a mere traffic inconvenience.

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If the wrong-way driver ever saw the sign, it did not register. The white car was headed east on the westbound side of I-287 near the Tappan Zee Bridge just after the morning rush.

As drivers scrambled to avoid the car, one semi-trailer truck sideswiped a sedan in the confusion. The drive of a New York State Department of Transportation help truck watched as danger approached.

The help truck driver, Dennis Vargas, said he was “a little bit” scared.

It has been seen plenty of times of times before – a confused or drunken driver crashing head-on into traffic in a wrong-way run. This time it was a medical emergency.

Vargas took a chance – using his emergency lights to position himself into the car’s path.

“I tried to stop the guy, because I know it’s going to be a disaster,” Vargas said

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It is about a mile and a half on I=287 from Exit 9 to the spot where the wrong-way driver finally stopped. Vargas was able to get him to slow down, but he was still moving along at a crawl — the car in gear, the engine running — and he had to get of the safety of his truck to finish the dangerous job,

“I got out of my truck, then I knock the window; and then finally open the door and put the car in parking and grab the keys,” Vargas said.

The driver never took his hands off the wheel, and never spoke.

People who have removed wrecks from the same stretch of highway following other wrong-way crashes know how bad it could have been.

“He did a wonderful job,” said Peter Dattino of Autobahn Towing. “He probably saved lives.”

Vargas’ bosses agree.

“Mr. Vargas went above and beyond to help the traveling public,” said state DOT spokeswoman Gina DiSarro. “He put himself in significant danger to prevent a potential catastrophe.”

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Vargas works both the morning and evening rush hours along the New York State Thruway and connection roadways.