HARRISBURG, Pa. - Pennsylvania's first volunteer "trucking army" was deputized yesterday with orders to protect the state's infrastructure and nab terrorists who might be lurking on the highways.

After a concentrated course in counterterrorism, the state's first 50 trucker recruits were authorized under a federally funded program to report suspicious activity to authorities - regardless of where they are or whether they are on duty.

"Today there is no more important duty that our professional truck drivers can perform than to assist in providing both safety and security on America's highways," said state Homeland Security Director Earl Freilino.

The Highway Watch program, now under way in 13 states, began in 1998 as a safety system to alert authorities to dangerous road conditions and stranded motorists. The American Trucking Associations, which administers the program, added antiterrorism after Sept. 11.

"What better way to spot suspicious activity?" asked Jim Runk, president of the Pennsylvania Motor Truck Association, which is recruiting truckers to participate.

So far, 2,000 truckers nationwide are authorized to report activity to a toll-free number where dispatchers direct calls to the appropriate authorities.