The dire predictions of heavy traffic yesterday turned out to be true for many people returning from Fourth of July getaways, according to transportation officials and travelers.

Traffic in the Washington area moved smoothly for much of the day, but by late afternoon, cars heading north on Interstate 95 in Virginia were backed up for 18 miles, from south of Dumfries to Springfield. In Maryland, travelers experienced stop-and-go traffic near Ocean City and as they made their way west across the Chesapeake Bay Bridge.

"It looks like everyone is coming back at the same time," said Marilynn Alexander, operations supervisor at the Virginia Department of Transportation's Smart Traffic Center.

Officials at AAA Mid-Atlantic had said it would be so, warning that late afternoon and early evening would be crunch time. About 634,000 Washington area residents had been expected to hit the beach and other destinations during the Fourth of July weekend, AAA said. Eighty-seven percent of area vacationers planned to travel by car.

Police did not report any major accidents by early evening. Some fender benders occurred along I-95 and elsewhere, and cars were abandoned on the side of some highways, possibly because they had been done in by the heat, police said.

The traffic alone was enough to make for a rough ride for many travelers. Lon Anderson, spokesman for AAA Mid-Atlantic, said backups such as the one on I-95 were especially difficult for drivers returning from vacations.

"Eighteen miles is tough," Anderson said. "One of the things that makes it worse is that people are usually very tired. They've had a long holiday weekend."

Adam Fletcher, 32, of Martinsburg, W.Va., was among the hordes of travelers making his way west over the Bay Bridge. He stopped his Jeep in Annapolis at 5 p.m. to get gas and to give his wife and two children a bathroom break. They had been driving since 2:30 from Easton.

"We sat in traffic, stop-and-go, from Easton," Fletcher said. "We just crept really slow at about 20 miles an hour. It's been really heavy."

"It's been a nightmare," said his wife, Melissa, 32.

Earlier in the day, traffic was relatively light, travelers said.

Arlene Robinson, 36, was returning to Newark, N.J., from Atlanta with her four daughters. She pulled off at a rest stop near Dale City, where she described most of the trip as "smooth sailing." Still, the congestion started to build farther north.

"I can always tell when we're near Washington," she said.

To the east, it was slow going as well.

Albert Mejia, 24, of Germantown described a slow-moving trip west over the Bay Bridge. He said he left Ocean City about 12:30 p.m.

"We left early, because everyone who goes to Ocean City leaves and goes in the evening," Mejia said. "We thought we'd miss the traffic, but no such luck. It was slow." He said driving the length of the Bay Bridge took about 15 minutes.

In the end, traffic was often in the eye of the beholder.

Barbara Shamp, who was heading back to Olney after a weekend in Raleigh, N.C., said the traffic was heavy. But her husband, Tom, said the traffic had not been that bad. They made their way up the coast before the 18-mile backup.

Barbara Shamp reminded her husband that they had come to a stop on I-95 three or four times. She said there was a reason her husband, who was in the passenger seat, had a different view of things: "He's been asleep," she said.

Staff writer Eric M. Weiss contributed to this report.

Traffic is heavy on northbound Interstate 95 yesterday afternoon in Prince William County, where cars were backed up for miles.