More and more employers are adopting global positioning system technology to monitor mobile workforces, and many workers are rankled by Big Brother's satellite eyes, reports the Associated Press.

Using GPS to track workers and vehicles is catching on with a growing number of business and government employers. Why? The goal is to improve productivity and customer service, and keep tabs on labor costs.

"If you're not out there baby-sitting them, you don't know how long it takes to do the route," said the manager of a waste disposal operation. "Now there's literally no place for them to hide."

UPS Inc. will distribute new hand-held computers to its 100,000 U.S. delivery truck drivers early this year, each equipped with a GPS receiver. The company says the feature will not be used to monitor workers, but to alert them when they're at the wrong address or help them identify an unfamiliar location.

But many employers adopting the technology, including many smaller firms, want to keep closer track of workers.

This past summer, for example, managers at Metropolitan Lumber & Hardware in New York worried when a new driver dispatched to a delivery just six blocks away still hadn't arrived after 3-1/2 hours. But using GPS, dispatchers soon tracked him down, "goofing off" on the other side of Manhattan, said Larry Charity, the company's information technology manager.

GPS systems can tell bosses how long their employees and vehicles have been at a specific location, what direction they're heading and how fast they're moving. Most systems can be set to alert a company if their employee spends too much time at a given location, drives too fast or strays into an area that an employer designates off-limits.

In Boston, 200 snowplow operators staged a protest last winter after the Massachusetts Highway Department said it would require all such independent contractors to begin carrying cell phones with GPS, as a way to track their efficiency. The city's school bus drivers also objected to a plan to install the receivers after a spate of complaints about late pickups.

The Chicago local of the Teamsters union complained to the National Labor Relations Board in 2001, after trucking firm Roadway Express Inc. installed GPS in rigs manned by unionized drivers.

"These systems could be used to unfairly discipline drivers, for counting every minute that they might or might not be on or off duty and holding that against them," said Galen Munroe, a Teamsters spokesman.

"We're talking about monitoring employees in every facet of their lives, and monitoring behavior that is more often than not, personal and not business related," said Jeremy Gruber, legal director for the National Workrights Institute, an advocacy group.

He cites instances of employers who have reportedly required some workers to carry GPS-equipped cell phones at all times, even when off work.