On the streets of Manhattan, motorists dodged orange traffic cones the other day as a crew snaked a black cable into a manhole. In San Francisco, taxicabs rattled over streets recently sliced up to make way for a similar wire. Tourists in Washington plugged their ears as a high-pitched power saw sliced into the streets of the capital. In Hickory, N.C., local leaders contemplated routes for a cable of their own.

From coast to coast, the digital age has arrived in America -- in the form of workers digging up streets in the blazing summer sun. Dozens of communications companies are in the midst of an unprecedented building boom. They're spending billions, block by painful block, to install thin glass fibers that can carry extraordinary amounts of information on waves of light.

Freed by Congress three years ago from burdensome regulation, heartened by the explosion of Internet use, these companies are part of a digital gold rush. They're clawing one another for rights-of-way and fighting to hire subcontractors as they race to bring high-capacity communications cables -- "fat pipes" -- to the nation's business districts.

Call it the Great Dig of '99. It has begun so suddenly that local governments are scrambling to protect their citizens from traffic hazards and to keep the streets in some semblance of repair. Court fights are breaking out across the country as cities and counties try to impose new fees and regulations on the communications companies.

Here and there, the new cables are being run to homes -- Starpower, the all-in-one TV, telephone and Internet service, is laying residential wires in parts of the Washington area. But for the most part, the companies see dense business districts as the profitable place to start. As soon as it makes economic sense to go to homes, the companies say, they will -- though that could be years.

Even without a push into homes, "we may be in the throes of the largest public works project in the history of this country," said Nicholas Miller, a Washington lawyer who advises local governments in their fights with communications companies. "This has sort of dropped on people out of the sky."

At least nine companies have been digging up streets in the Washington area in recent months to install glass fibers. Some downtown streets look like the abdomen of a surgical patient. No sooner does one company finish installing a cable than another wants to come in behind it and dig another trench, a fact that has forced the city to slow down permanent repairs.

The temporary repairs done by the fiber companies don't last long, with the result that the city's streets, not exactly glistening ribbons of asphalt to begin with, have grown worse.

Gary Burch, the District's chief engineer, promises that things will get better. Many of the fiber companies are due to wrap up their work in Washington by this fall, and at that point lasting repairs can begin. "You'll see more and more permanent repairs in the next few months," Burch said.

Downtown Washington is by no means the only place in the region where fiber companies are at work. They're wiring suburban business districts with heavy concentrations of technology firms, such as Greenbelt, Reston, Herndon and others.

Gene Aldridge, an engineer from Texas who travels around the world from fiber dig to fiber dig, stood in worn cowboy boots and a white hard hat last week in a warehouse in Sterling, on his way to supervise a dig near Dulles International Airport for a company called E.spire Communications Inc. He wrapped his fingers around a bundle of glass fiber. "This stuff," he said, "is literally the future of the world."

He said that it's easier to run cables through the suburbs because there often is room beside the road. But there have been problems nonetheless. When companies laid fiber down Maryland's River Road toward the District recently, cutting up new pavement in the process, residents were dismayed at the mounds of debris that got dumped by the road. Montgomery County regulators are planning a big push to tell contractors how they're expected to behave -- and to crack down if they don't comply.

At the center of all this frenzy are flexible glass fibers not much thicker than a human hair. These fibers are wound into bundles and then coated with plastic to make them look like any other kind of wire. But they are exceptional. With the right lasers and other equipment at either end, a thin fiber can carry the equivalent of 3.1 million telephone calls at once. By next year that figure should hit 25 million.

Fibers of this sort have been in use for 20 years, and they have been available in major cities for more than a decade, but not on the scale they're now being deployed. Soon there will be hundreds, even thousands, of glass strands running up and down city blocks and suburban business districts all over the country. Moreover, companies are creating empty conduits as they go so that even more fiber can be installed later with minimal effort.

The fibers can and will carry telephone calls -- in the digital age, a human voice can easily be turned into the ones and zeroes of computer language, converted into pulses of laser light and turned back into a voice at the far end. But it is not voice traffic that's driving the gold rush. It is the boom in demand for high-capacity computer networks.

Businesses want fast Internet connections and speedy links to their far-flung offices and data centers. People want to send live video and other enormous files over networks. As online commerce skyrockets, companies that hope to compete need the ability to serve up millions of pieces of information at once.

This mushrooming demand coincides with a new era in telecommunications regulation. In 1996, Congress passed a law designed to sweep away the last vestiges of the old Bell System monopoly and bring competition to all kinds of communications services.

Bell Atlantic Corp., the region's dominant local phone company, has had fiber cables beneath the streets for years. What's happening now is that competitive companies, some small, some large, are stepping up construction of their own networks so they can compete with Bell Atlantic and with one another.

Fiber is by no means the only technology competing to supply high-capacity data links -- wireless ground transmitters and satellites are being deployed to do the same thing. But in this season of backhoes and fuming motorists, fiber is certainly the most visible.

Court battles have erupted in Florida, Texas, Michigan and other states as local governments try to impose new fees and regulations on the companies. Courts around the country have split on how far the governments can go.

One of the key battles was fought in Prince George's County, where the county government tried to collect a percentage of gross revenue from the communications companies as compensation for letting them use public rights-of-way to run their cables. A federal judge rejected that plan, but the county plans to appeal.

"Local public rights-of-way are being used all over this country to make profits for these companies, and the local jurisdictions are not even being considered," said Prince George's County Council Chairman M.H. Jim Estepp (D-Upper Marlboro). "It's akin to confiscation of public property without compensation. Who cares about the average public if you are making that kind of money?"

Many jurisdictions, including Washington, have laws that say companies that dig up the streets must pay to repair them. But critics say the ordinances are often outmoded and don't recover the full cost of repairs. Moreover, few cities have laws on the books that allow them to receive continuing compensation for companies' use of their property.

Other cities, notably San Francisco, have recently adopted ordinances encouraging companies to work together to minimize disruption. "Hopefully, we inconvenience people once, not six times," said Cynthia Chono, street coordinator construction manager for the city of San Francisco, where this month alone about 100 of the city's 12,000 blocks are being worked on.

Miller, the lawyer who works with local governments and helped defend Prince George's in the court fight there, warns that the sudden boom has outstripped the ability of cities and counties to control it.

"Where this is going to hit the fan is when all these cities are faced with enormous reconstruction bills to rebuild their streets," he said. "It's going to show up in the next three or four years as a huge hit on the local taxpayer. This is a living, breathing example of why people are so cynical about their government."

Not so fast, say the communications companies. They acknowledge that this year's construction has been an inconvenience, but they say the long-term gain will be worth the pain. And they argue that letting local governments milk them will only slow the arrival of the digital era.

"Cities have, unfortunately, seen the influx of telecommunications carriers as a revenue opportunity," said Charles Kallenbach, vice president for regulatory affairs at E.spire, an Annapolis Junction, Md., company that is building new fiber links around the country. "Our feeling is that it greatly benefits the business and residential users to have more telecommunications facilities. Cities should be making that easier rather than more difficult."

Some of them are, in fact. They are smaller towns that see attracting a fiber company as a critical step for their future economic development. With fast fiber links, they are less isolated and better able to compete with the big cities for new jobs and companies. Without such links, they fear being left behind as the digital economy zooms forward.

In Hickory, N.C., a town of 35,000 in the midst of a booming area an hour northwest of Charlotte, local leaders were so keen to bring in a fiber company that they flew to New Jersey 18 months ago to meet with one, towing fancy slides and a sales pitch.

"They showed up with a wonderful presentation," said Michael A. Sternberg, president and chief executive of KMC Telecom Inc. of Bedminster, N.J. "They sold us on the city. We expect to have Hickory in service by the end of the year."

His company has specifically targeted smaller communities, not least because everybody else has rushed into the big cities. In smaller places, fiber can usually be strung on light poles instead of buried, a less disruptive procedure. Sternberg sympathizes with people in the big cities. "One guy comes in and tears up the street, then another guy comes in and tears up the street," he said. "Pretty soon the citizens say, `Enough. We'd like to be able to drive to work in the morning.' "

On the corner of 55th Street and First Avenue in Manhattan the other day, Kevin Cotter watched fiber coiling down an open manhole. The 38-year-old worker for Hylan Electrical Contracting lamented the dirty stares he got from motorists as they negotiated their way around the company's orange construction cones. His employer has tripled the number of crews laying cable for various fiber companies in the past year, and Cotter is working six days a week to help his crew keep pace.

"I've been laying fiber all over the world for years," he said. "In Hawaii for a Japanese company, in the Caribbean after the hurricanes. But right now is unbelievable. There's more fiber than you can imagine, on every corner you look. Everybody I know is going crazy over it, putting all their money into the stock. I'm putting in every last dime, too."

Staff writers Liz Leyden in New York, David Streitfeld in San Francisco and Cassandra Stern in Los Angeles contributed to this report.

Under Expansion

Telecommunications traffic is projected to grow more than 11-fold by 2002, fueled by explosive growth in Internet use.

1998

Voice 55%

Internet 3%

Other data 42%

2002 (projected)

Internet 64%

Voice 7%

Other data 29%

SOURCE: Ryan Hankin Kent Inc.

CAPTION: Major Loads (This graphic was not available)

CAPTION: Construction worker Lorenzo Ford helps guide piping for fiber-optic cables into a trench in Reston.