D.C. Mayor Anthony Williams (D) today will announce new rules requiring telecommunications companies to finish installing fiber-optic cable under a street within 120 days of getting a permit, amid a growing chorus of complaints about the torn-up condition of city roads.

The utility work has carved wide swaths into road surfaces, blowing car tires, tossing messengers from their bicycles and rattling motorists' nerves like a jackhammer in bedrock. And city officials concede that the new deadlines won't spare motorists from the next blow: a winter of painful potholes.

The temporary patching that crews are putting on the two-foot-wide cuts is more vulnerable than permanent asphalt to the freezing-thawing conditions that cause potholes in cold weather, said Gary A. Burch, the city's chief engineer.

"The freezing and thawing will create some monster potholes," said Lon Anderson, spokesman for AAA Mid-Atlantic. "Given the amount of cable they're laying, if we have anything less than a mild winter, we're going to have potholes that will do some real damage to vehicles."

Street work around the city has increased sharply in recent weeks because of a rush to install underground cable for new telephone, cable television and Internet services. The disruption has been made worse by the unlimited time that telecommunications companies were given to complete repairs to a street they had dug up, Burch said.

"We've had a lot of temporary repairs around the city that could have moved faster but didn't," Burch said. "What we're trying to do now is to move things along, make the time lines tighter."

Burch acknowledged, however, that the city will grant waivers to companies that cannot meet the city's new 120-day timetable because their work is too complicated.

An official for Starpower Inc., which has the most ambitious construction plan of any of the telecommunications companies and plans to dig up every street in the District, said that 120 days is usually a realistic time frame.

"It's a reasonable amount of time, but it depends on the length of cable you're laying," said Tony Peduto, general manager for Starpower. The company expects to lay 900 miles of cable by 2001 and has 40 crews spread across the city.

In all, nine telecommunications companies hold about 145 permits to lay pipe and fiber-optic cable beneath city streets, Burch said. He said about half of that work is complete.

The work, which began slowly in the spring, has exploded and suddenly seems everywhere. First, the day-glo orange markings appear overnight on the pavement, declaring a street's future in a code indecipherable to lay people. Then the pylons pop up, street parking is banned and the demolition begins.

Often, competing companies will attack the same street in succession, and the road becomes a serial victim--sliced open, patched up and then sliced open again with the next work crew. Cars, trucks and taxis are continually bobbing and weaving, rolling over metal plates, around blinking message boards, over holes.

"It's like a war zone," said Steve Cohen, 44, who nosed his Jeep out of a parking garage onto L Street NW yesterday near 17th Street, where the asphalt was missing in large chunks and the manhole covers stuck up menacingly through the naked concrete.

The road work has not yet hurt Cohen's Jeep. "Just my psyche," he said. "You're driving, and you feel like any moment you're going to fall through a steel plate or lose a wheel."

Peter Abrahams, 34, said the utility work left his 1993 Honda Accord with chipped paint and damage to the axle assembly. "It's just been a nightmare," said Abrahams, who commutes to L Street NW from Vienna. "My car sounds like a bag of bolts--it rattles, it shakes." He said he paid for the paint to be fixed because he didn't know whether he could make a claim against the contractor.

Burch said motorists who suffer car damage because of construction can either file a claim with the contractor or alert the mayor's office.

At the Embassy Mobil station on P Street NW, which offers a $120 "D.C. Streets Special" that includes a realignment, brakes check and tire rotation, manager Jon Harvath said one woman rolled in this week with a two-inch gash in her tire from driving over a metal plate covering a utility trench on 22nd Street. "There's definitely been a noticeable surge in sales," he said.

The bike messengers who work at the Metropolitan Delivery Corp. on Pennsylvania Avenue NW, not far from the White House, are feeling every bump, said Jimmy Snyder, the service's general manager. One messenger hit a pothole last month and slid in front of a car, ending up in the hospital with cuts and bruises, Snyder said.

To install pipe or wire, utility companies typically break through a two-inch top layer of asphalt and about 10 inches of concrete until they reach soil. They bury the conduit, then backfill the trench with dirt and put a thin layer of asphalt on top. That is the temporary patch, which is often rough and bumpy. At 22nd and L streets NW yesterday, the patch had become a sinkhole large enough to swallow half a car tire.

Later, the company hires a construction firm to dig up the temporary patch, fill it with concrete and cover it with a permanent asphalt.

Under the plan that Williams will announce today, utility companies will have 60 days from the time of permitting to install their pipe or wire, then 15 days to begin permanent repairs and 45 more days to finish those repairs and return the street to the condition in which it was found, Burch said.

The mayor also has instructed the companies to finish all their work downtown by Thanksgiving.

Burch said the city cannot refuse requests from competing companies to bury cable on the same street.

"Every jurisdiction is having the same problem," said Burch, who just attended a national conference called "Peaceful Coexistence Between the Communications Industry and the Department of Public Works."

Some jurisdictions have been more aggressive than the District in trying to impose new fees and rules on the companies, and courts have split on how far local governments can go.

When will the utility work calm down? "The answer is, we don't know," Burch said. "No one knows the size of the market. The mayor is concerned about it; we're all struggling. We acknowledge the rights of these companies to be in public space. And we're happy they're here, because it's an indication of economic vitality. But we have to find a way to control it in some way."

Staff writer Allan Lengel contributed to this report.

CAPTION: Workers install fiber-optic cable at 16th Street and New York Avenue NE. The work by telecommunications companies is hard on tires and nerves.