The American Automobile Association warned motorists yesterday that some of the Washington area's most heavily traveled intersections are also the most hazardous.

The AAA called these intersections--three in the District, five in suburban Maryland and four in Northern Virginia--the "dangerous dozen" and said that the 12 account for an average of one accident a day and one fatality a month.

The juncture cited as the worst by the AAA report released yesterday actually encompasses two intersections--the area stretching along Interstate 95 from the Capital Beltway to Old Keene Mill Road. Three persons were killed in one accident last year on that stretch, which handles more than 141,000 vehicles a day and is the site of more than 100 accidents a year.

Tom Crosby, a AAA spokesman in Fairfax, said at a news conference yesterday that the "dangerous dozen" were named to draw public attention to intersections where motorists should exercise extra caution. The AAA also wants to build support for increased highway funding to correct dangerous road conditions, Crosby said.

Crosby said the AAA selected the intersections based on the number of accidents and injuries recorded at those sites, the traffic volume and the length of time the intersections had been considered dangerous by District, Maryland and Virginia highway departments and police.

Area highways experts at the news conference cited poor engineering and inadequate traffic signs and signals as factors contributing to dangerous intersections. But in most cases, they said, the high volume of traffic was to blame for most of the problems.

"The bottom line is congestion," said Maj Shakib, district traffic engineer for the Maryland Department of Transportation. "It is not that these intersections are by design dangerous."

Shakib and other officials for Virginia and District transportation departments said their agencies routinely review traffic accident trouble spots and seek ways to correct dangerous road conditions.

Shakib said that at two of the five Maryland intersections named by the AAA, major improvements are being planned to better accommodate increased traffic volume.

For example, he said the intersection of Norbeck Road and Georgia Avenue in Montgomery County will be upgraded in the next several years through a $10 million project to widen Norbeck from a two-lane to a four-lane road.

At the Branch Avenue and Woodyard Road intersection in Prince George's County, Shakib said plans are being made to build a diamond-shaped interchange that would bring Woodyard over Branch and reduce traffic congestion.

David Gehr of the Virginia Department of Highways and Transportation said highway planners did not anticipate the extensive increases in traffic volume that developing suburban communities would exert on existing roadways.

"As long as we have growth in Northern Virginia, the traffic will continue to overwhelm the intersections," he said.

Correcting the problems will be difficult because "there isn't enough money to make all the improvements," Gehr said.

The Washington area's most dangerous intersections, accidents recorded and proposed improvements are:

DISTRICT--New York Avenue (Rte. 50) and Bladensburg Road NE; 14 accidents in the first quarter of 1983; new traffic signal and installation of skid-resistant surface.

Branch Avenue (Rte. 5) and Pennsylvania Avenue SE; 16 accidents in the first quarter of 1983; signal warnings and skid-resistant surface.

Interstate 295 and Portland Street SE; 8 accidents in the first quarter of the year; minor changes in ramps and signal on South Capitol Street.

MARYLAND--Route 301 and Collington Road (Rte. 197); 34 accidents recorded in 1981; traffic signal timing changed for left turns.

Greenbelt Road and Good Luck Road; 22 accidents in 1981; left turn signal being considered.

Branch Avenue (Rte. 5) and Woodyard Road (Rte. 223); 39 accidents in 1981; a major interchange is planned.

Norbeck Road (Rte. 28) and Georgia Avenue (Rte. 97); 22 accidents in 1981; road widening planned.

Montgomery Village Avenue at North Frederick Avenue (Rte. 355); 36 accidents in 1981; improved traffic signal timing.

VIRGINIA--Interstate 95 and Interstate 495 at Old Keene Mill Road in Springfield; 123 recorded last year; construction of Springfield Bypass and interchange at Backlick Road and Old Keene Mill Road.

Arlington Boulevard (Rte. 50) and Annandale Road (Rte. 649); 57 accidents last year; turn lanes on Annandale Road and coordinated signal system.

King Street (Rte. 7) and Beauregard Street in Alexandria; 25 accidents in 1982; synchronizing traffic signals for better traffic flow.

Columbia Pike (Rte. 244) and Walter Reed Drive; 22 accidents in 1982; area being studied.