When Herbert Northern came to Alexandria as a state police sergeant in 1976, a rush-hour accident on the Capital Beltway could be cleared in 30 minutes, there was no light at Rte. 123 and Davis Ford Road in Prince William County, and Northern Virginia was such an undesirable assignment that whenever a state trooper could ask for a transfer, he did.

When he retired last week as commander of state police in Alexandria and Fairfax, Arlington, Prince William and Loudoun counties, a Beltway accident could tie up traffic for hours, and he recently sat through 22 light changes at the Davis Ford Road and Rte. 123 intersection. But of the 80 troopers eligible to request transfers this month, only four have done so.

The 115 troopers in the state police's 7th Division occasionally assist local police with drug raids and civil disorders and sometimes investigate crimes such as drug smuggling, but most spend almost all of their time policing highway traffic.

"It's boring and it becomes very stressful to be assigned to a highway like the Capital Beltway, and stay there for an eight-hour period," Northern said. "There's no place to go to relax. There's no place to go to get away from it . . . . If there is such a thing as burnout, I think it causes it."

During the last 12 years, traffic volume on the area's highways has increased about 60 percent. This means, for example, that for every minute an accident or storm stops traffic on the Beltway, it takes four minutes to get traffic moving freely again.

But turnover among the state police officers has decreased under Northern (as it did under his predecessor Robert Suthard, now state police superintendent) partly because of the 20 percent extra pay they now get for serving here, troopers say. The mandatory minimum tour of duty has been extended from one year to two, and a new headquarters building added on Braddock Road, replacing an older building on Rte. 1. Troopers also credit Northern's low-key leadership and concern for his subordinates with improving retention.

"I've never heard anybody speak bad of him the 30-some years since he put a badge on," said retired trooper P.P. Herndon. "He's a smooth operator. He doesn't get excited."

Northern, 60, started his career with the state police 37 years ago after a tour in the Navy. He worked 20 years in other parts of the state, mainly in Fredericksburg, as a trooper before the slow path of promotion made him a sergeant, and later moved him to Northern Virginia. He became a captain in 1983.

As Northern Virginia commander, he has stayed largely out of public view. One exception came a year ago when he remarked that commuters who put their children in their car to meet HOV restrictions were not complying with the spirit of the law.

But local police officials know him as a soft-spoken team player who has maintained good relations with the county and city police forces in his jurisdiction.

During a 90-minute interview, Northern never cracked a smile. But he did become, if not excited, at least loquacious on the topic of Northern Virginia traffic.

"It's going to get worse before it gets better," he said, predicting that within five years, morning commuters will be backed up to the Quantico Marine Corps Base. "You're faced with what seemingly is an impossible transportation system of inadequate highways that simply cannot handle the volume of traffic that's out there. You're expected to make this all work. And you can't . . . . You cannot continue to put up temporary Band-aids, paint white lines and put up barrels."

"Enforcement is not the complete answer," he said, explaining that at least 10 percent of the 160,000 drivers who use the Beltway each day violate a traffic law of one sort or another. If all the violators were ticketed, "where would we find the judges?"

Only two things can cure the area's traffic problems, he said: another bypass around Washington to reduce Beltway traffic, and more public transit.

"The Washington bypass is a necessity. It's got to be done. If not, you fellows are going to be sitting in traffic jams the rest of your days . . . . Without the bypass, or without the extension of the Metro . . . the Washington area will be at a standstill."

He declined to blame any single government or agency for the transportation situation. "I think the blame can be shared," he said. But he said he believes the state is paying more attention to the area now, and noted that transportation was a major issue in the November elections in Fairfax County.

But for himself, he has another solution. He plans to leave Northern Virginia, moving from Manassas to the Fredericksburg area. "I really don't look forward to continuing to drive in this traffic."