When some city of Pittsburgh employees tried to check the Internet Tuesday, they got an unusual message.

Up popped a note saying the site where they were headed was "filtered." If they wanted to proceed, they had to click on a button that said "Use Quota Time." They'd then get 10 minutes to browse -- one of three such sessions they'd get that day.

It was the same for any Web site they checked. Turns out the message reflects a new city policy restricting many employees' Internet access, for any purpose, to 30 minutes a day.

Announced in a memo Tuesday, the policy has been rolled out in the Public Works Department, which handles street repair, engineering, trash collection and building maintenance.

The policy has provoked grumbling in the halls of the City-County Building, but this is just the beginning.

Eventually, the city hopes to restrict Internet use for nearly all of its 1,300 employees with Web access, said Howard Stern, the city's chief information officer. Exceptions would be few.

"This is part of professionalizing city government," he said, adding that the city could shave its $1,500-a-month Internet service bill and keep employees from surfing the day away.

Experts say restrictions on employee Internet use are increasingly common in private industry and government. Companies and governments want to keep workers on task and prevent legal problems that can occur when employees visit potentially offensive Web sites.

The city's approach, though, is unusual, and could have a down side.

Pradeep Khosla, dean of Carnegie Mellon University's College of Engineering, said it was the first time he had heard of an employer imposing time limits on Internet access. A city employee, he noted, might want to use the Internet to "look at what other cities are doing or what the federal government is doing, and that takes time."

Even saving money by booking city-related air travel online could burn 30 minutes, he said.

Mr. Stern said the city does not keep statistics on how much time workers spend online, but the 30-minute limit could cut deeply into the gigabytes flowing through the city's high-speed data lines. He said just 30 percent of the city's Internet use is related to management functions.

Last year, the city had to upgrade from three to four data lines, he said, which added several hundred dollars a month to its telecommunications bill. Even with the fourth line, he said, worker Web surfing sometimes clogs the data line so much that it takes employees a long time to download legitimate, work-related information.

"By [employees] not being on the Internet, we'll have more room in our pipe, so to speak, to allow work-related searches to be done faster," said Mr. Stern.

It doesn't cost the city anything to limit Web surfing, he said. The city already uses a program by San Diego-based Websense Inc. that prevents employees from visiting pornographic or gambling Web sites. A free update included the time-limit option.

He said employees can still check personal e-mail accounts, though the memo said personal e-mail eventually "will be restricted, if not eliminated altogether."

Allegheny County's software keeps its employees from checking personal e-mail on county time and blocks access to many Web sites. County spokesman Kevin Evanto said he recently was foiled in his efforts to visit the Super Bowl Web site.

All county employees sign an Internet access policy, which bars all but minimal personal use. There is no online time limit, Mr. Evanto said.

Similarly, at PNC Financial Services Group, employees can make very limited personal use of the Internet, but aren't timed.

At the county and PNC, employees are told to assume their Internet use and e-mail may be monitored.

Such policies are becoming common, said Garen E. Dodge, an attorney specializing in Internet law at Washington, D.C.-based Wiley Rein & Fielding. Time limits are less common.

"Is it reasonable to limit to 30 minutes a day?" he asked. "I don't see anything wrong with that. ... It's well within their rights" as an employer.

At the city, it's an issue of productivity.

"Do you want people doing political work on [city] computers?" asked Dick Skrinjar, spokesman for Mayor Bob O'Connor. "If we have 1,300 people reading the newspaper for 30 minutes a day, that's 650 hours."