IF YOU'VE followed the series of editorials that have appeared in this space on the theme of "Getting There," you may be thinking along about this time that there should be a companion series called "Not Getting There." A large part of it would be devoted to trucks.

On Friday the driver of a tractor-trailer lost control of his vehicle on the Capital Beltway and was killed in the crash that ensued. For those who were caught in the traffic jam and didn't read the paper Saturday, we repeat a little of reporter John F. Harris' account, which sounds somewhat like a description of Memorial Day at Indianapolis:

"Matt Whalen of Bethesda, said . . . his was the first of six vehicles to be struck by the truck. . . . Whalen said he was driving two lanes in from the median when he saw the truck overtaking him in the lane to his left. He said the truck crossed into his lane and hit his vehicle, smashing the trunk of his sedan all the way into the back seat. . . .

"After striking Whalen's car, witnesses said, the truck struck a red Datsun carrying three passengers, slipping the car into the air to clip another while airborne before skidding further down the highway. . . . '(The truck) slingshotted the car right on its roof,' said Ricky Shevits of Manassas, whose vehicle was also struck by the speeding truck. "The car went speeding right past me on its roof."

A Virginia state trooper said later: "It's safe to say . . . there were defective brakes" on the truck, although that's a question subject to further investigation. It might be defective brakes in one accident, defective tires in another, excessive speed in a third as the list of thrills, spills and deaths grows on the circumferential highway that many thousands of us travel every day with mounting trepidation.

There's a dangerous game being played out there, in which a drivers' network of CB radios relays the word that the coast is clear of police radar, and the inside lanes fill up with cars and trucks going as much as 20 or 30 miles over the speed limit. The cars are bad enough, but when something goes wrong with a fast-moving tractor- trailer, there is real trouble.

John F. Herrity, chairman of the Fairfax County Board of Supervisors, says it may be necessary to restrict trucks to 40 miles per hour and forbid them to pass other vehicles. It's time at least to start thinking in such terms. There would be howls from the trucking industry that such a slowdown would cost consumers a fortune. It would also cost a lot to perform adequate mandatory inspections on these behemoths of the road, but it needs to be done, because the cost of what's happening on the Beltway now is definitely too great.