Robert T. Jones fidgeted as he stood before Prince George's Circuit Judge Robert H. Mason, wondering what the judge would say about him being five hours late for his arraignment on a traffic charge.

"Where were you at 8:30 this morning?" Mason asked the 37-year-old man Friday.

Jones started explaining, as he had on other occasions to different judges, about the difficulty in getting the more than 12 miles from his home in Southeast Washington to court in Upper Marlboro -- especially when his pending charge prevented him from driving a car.

Jones' predicament is not uncommon around the courthouse in Upper Marlboro. Familiar with the problem, the county transportation department will try to remedy the situation by beginning a shuttle bus service today to link Upper Marlboro with the end of the bus and Metrorail lines about a dozen miles away.

Citing his own problems getting to the courthouse, Jones said that his friends and relatives who drive cars hesitate to take time off from jobs to take him eight miles beyond the Beltway to Upper Marlboro, an almost rustic town that is home to the Prince George's County government.

Jones has tried a cab. But a note in his court file said that two weeks ago Jones had waited at home all day for a cab to take him to the courthouse. The cab never showed.

Buses are not the answer, Jones said. Metrobuses stop about 10 miles from the courthouse along Pennsylvania Avenue -- the main route between Jones' home and Upper Marlboro -- and long before the road's scenery changes from apartment buildings to grazing horses.

But Judge Mason had heard enough of the excuses. "If you don't come the next time," Mason told Jones, "I will issue a bench warrant for your arrest."

Jones left the courtroom, frustrated but relieved to have the court session behind him.

"They don't seem to understand," he said in an interview. "If you call up the court, they tell you to hitchhike. Court is important, but what decent woman or man is going to hitchhike up Pennsylvania Avenue?"

"It's as simple as this," said Jones, who had to give a friend money for gasoline and to pay for the hours she missed at work when she took him to the courthouse. "If you don't have access to a car, you can't find a way out here."

The shuttle, which will run Monday through Friday from 7 a.m. to 11 a.m. and 1 p.m. to 6 p.m., will pick up passengers from the Landover and Addison Road Metro stations and in front of the Penn Mar Shopping Center on Donnell Drive in Forestville. One-way fare is $1.

The county tried a shuttle service in 1974, running buses from Pennsylvania and Alabama avenues and Mount Rainier to Upper Marlboro.

The service ended after several months, said assistant chief of transportation John Johnson, "because we had no ridership at all."

But the court caseload has increased since then.

Now, five district courts operate in Upper Marlboro, compared withone in 1974, according to Patricia Platt, administrative clerk of District Court. And 12 years ago, there was no Metrorail service to the county. Officials say the rail system will be a feeder route for the bus system.

"There's no doubt that people will use the shuttle bus," Platt said. "They usually wait until the last minute to call us. First, they call Greyhound, then they call us. But they always wait until the morning of their court date."

Court personnel, who have had to make do without public transportation to their jobs, are ecstatic about the prospects.

"It will make my job easier," said Mary O'Dell, the jury commissioner who sometimes spends half a day each week arranging car pools for about 10 of the 80 new jurors who are without cars. "Sometimes I have to go begging."

The District Court has distributed about 2,000 brochures about the shuttle service to the five District Court Commissioners around the county. And the state's attorney's office, which has paid $887 in cab fares for victims and witnesses to go to court in the past nine months, is handing out the brochures.

"We spend a lot of time asking [victims and witnesses] to please, please ask a relative, friend or neighbor to give them a ride," said Sondra Ricks, coordinator of the state's attorney's Victims Assistance Program.

The isolation of Upper Marlboro has caused some touchy situations for attorneys, who do not want to be accused of tampering with witnesses, for example, in arranging transportation to the courthouse.

Attorney Steven P. Lemmey, a former assistant state's attorney, remembers once giving rides to the New Carrollton Metro Station to an 18-year-old woman he had just prosecuted and the district court judge who had given her probation. He had to give them a ride, Lemmey said, because the case was finished after darkness fell and he did not want the woman hitchhiking then.

"We were riding down Rte. 202," Lemmey said, "and I was thinking to myself, 'Please don't get in a head-on collision. It just wouldn't look right for us to be in the car together.' "

But some people are not sure that the new bus system will solve the problems of getting to court. Circuit Judge Vincent J. Femia thinks the shuttle service "will really screw up one of the classic excuses about being late or absent" for court dates.

Femia said defendants now will likely use the second-most heard excuse when they are late or absent: that a relative in North Carolina has died.

"The way I see this," Femia surmised, "the roads in North Carolina are going to be clogged with funeral processions. The people there are in for a helluva year."