In a hurry? Thinking about nudging your car just a little over the speed limit? If you're on Shirley Highway or the Virginia Beltway, you might think again. The chances are better than ever that a Virginia state trooper is just around the next bend.

In the past eight months, increased state police patrols on the Beltway and Shirley Highway, the two roads most often patrolled by state troopers, have resulted in almost 5,000 more arrests than during the same period last year.

Last February, 16 additional state troopers were assigned to cover Northern Virginia in anticipation of the December opening of I-66. And with still more troopers expected early next year, motorists will be seeing the most intensive state police coverage of interstate roads in Northern Virginia in recent history.

The major result of the increased patrols is the number of arrests. By July 31, troopers had made 16,893 arrests on the Beltway and Shirley Highway (I-395), 4,937 more than for the same period last year.

Arrests for speeding -- 6,000 of them -- make up almost a third of the total, according to State Police Capt. Robert Lee Suthard, and are about 1,400 more than for the same period last year. Drunken-driving arrests totaled 455 by July 31, or 184 more than the same period last year, while arrests of motorists driving with suspended licenses total 410, or 126 more than the same period last year.

One of the biggest jumps in arrests was for hitchhikers: 256 by July 31, compared with 28 for the same period last year.

Arrests also included a number of impatient commuters who have jumped the gun on using the still-unopened 10-mile section of I-66 inside the Beltway, which state police have just begun patrolling. Only buses are allowed to use the nearly completed highway until Dec. 22, when it will be opened to carpools during rush hours and all motorists during other times.

The Virginia Legislature authorized the transfer of additional state troopers and two new state police headquarters in Northern Virginia to ensure enforcement of the special traffic restrictions on I-66 and Shirley Highway and the growing traffic on the Beltway.

Although I-66 will have computerized traffic controls, entrance gates and electronic monitors, none of the new equipment is expected to be installed before April. In the first few months of I-66 operation, state troopers will be the only enforcers.

The electronic system, which also is to be built into the portion of Shirley Highway inside the Beltway in 1984, will meter traffic, limit access to the highways when they have reached capacity during rush hours, monitor speed and give state police television coverage of the roads to spot accidents and breakdowns.

Even the I-66 parallel bike trail, which already is opened into Rosslyn, will be lighted at night and monitored 24 hours a day by TV cameras.

A new, $750,000 state police headquarters, the first inside the Beltway, is being established on Columbia Pike near the Pentagon. It will house computers and TV monitors for both I-66 and Shirley Highway, as well as a contingent of 25 state troopers and three supervisors now assigned to work primarily inside the Beltway.

Until February, only 50 state troopers were assigned to Northern Virginia, including Fairfax, Prince William, Loudoun and Arlington counties. When vacancies are filled, there will be 70 troopers, including 25 inside the Beltway, to cover Northern Virginia, according to Suthard.

A new Northern Virginia division headquarters, where Suthard will oversee area operations, is now being built on Braddock Road. It will replace aging and temporary quarters on Rte. 1 near Mount Vernon and another office in Newington in Fairfax County.

Until July, when troopers serving in Northern Virginia got a pay raise, the Washington area was considered a hardship post that few troopers took voluntarily. Because of the much higher cost of living here and the higher pay for comparable jobs, all Virginia state employes working in Northern Virginia receive pay differentials.

The legislature increased the differential for state police from 12 to 20 percent two months ago, which came on top of a 4 percent general pay increase for state employes. With a top starting salary of $18,256 a year, Suthard said, state police pay is now comparable to that for other Washington-area police officers.