Icy road conditions and the remnants of last week's snowstorm delayed thousands of metropolitan area commuters yesterday and slowed the morning rush hour to a caterpillar-like pace in some areas.

Because of the delays, many commuters did not reach Washington until after 9:30 a.m., the time the official rush hour ends and traffic signals are adjusted to handle the normal midday traffic volume. As a result, some traffic lanes were quickly filled with parked cars and other in-bound lanes were changed to direct traffic out of the city.

Among the commuters who arrived late for work were several members of the U.S. Supreme Court, including Chief Justice Warren E. Burger. The court, which prides itself on starting punctually at 10 a.m!, did not convene until 10:18 a.m., the latest starting time in 22 years, according to Michael Rodak Jr., the court's clerk.

Commuters and traffic officials reported particularly heavy traffic on Pennsylvania Avenue, MacArthur Boulevard, Key Bridge, Shirley Highway and the Whitehurst Freeway.

Jack Hartley, assistant director of the D.C. Department of Transportation, said salt trucks had been sent out at 6:30 a.m. to spread salt on streets where isolated ice spots had developed because of a heavy dew in the early morning hours. But Hartley described the rush hour as normal for the most part.

For Fairfax County School Superintendent S. John Davis, however, the morning was anything but normal. Davis said some county school buses encountered difficulties getting through unplowed subdivision roads and were delayed by as long as two hours. Other bus runs had to be canceled altogether, Davis said.

"It's my understanding that there were some roads which could have been sanded or plowed over the weekend but were not," Davis said.

The Clifton and Reston sections of Fairfax County were reported to be in particularly bad shape. "We seem to be in a little pocket that has had no salting or sanding on anything," remarked Marie Koneczny of 7313 Blue Dan La. in Clifton.

Koneczny said one roads were in such poor shape that school buses had not been able to pick up students in some instances.

Metro officials reported two train breakdowns during the heart of the morning rush hour causing delays of half an hour or more and creating the worst morning for Metro in several months.

A train stalled in the Foggy Bottom station at 8:02 a.m. and caused a delay of about 10 minutes on the Blue Line.

A second breakdown occurred at 8:33 a.m. in Metro Center on the track heading for the Stadium-Armory Station. Passengers were evacuated and the train was taken to a cross-over track, but the train broke down again in the middle of the crossover and blocked the tracks in both directions for several minutes.

"This is the worst one we've had in a long time," said Anthony J. Stefanac, Metro's general rail superintendent.