The Loudoun County Board of Supervisors is considering altering the county master plan so developers can build a regional shopping mall at the intersection of routes 7 and 28.

Chances for changing the master plan, however, are clouded by predictions of extremely heavy traffic on the two routes in the next few years, officials said.

County planners predict that Rte. 7 in eastern Loudoun County will be handling peak loads of about 100,000 cars a day within the next seven years, while traffic on Rte. 28, which serves the county's major industrial corridor, will be growing to about 68,000 cars a day. Both roads currently have a capacity of 41,000 cars a day.

County supervisor Frank Raflo (D-Leesburg), chairman of the committee studying the master plan change, has asked all board members to discuss possible zoning solutions to the traffic problem at a meeting of the public services committee to be held within the next few weeks.

"Changes in land use could mitigate the traffic problem," Raflo said last week. "The question for the board is what changes could be made through rezoning that would redistribute the burden of traffic."

Another public hearing would be held before the full board should any zoning changes be recommended by the committee.

The Loudoun County Board of Supervisors adopted a management plan in 1980 that designated the intersection of routes 28 and 625 as the site for a regional shopping mall. But two developers, the Lerner Corp. and the Sunrise Development Corp. of Pittsburgh, have filed competing requests to build a mall at the Rte. 7 and Rte. 28 intersection.

It appears unlikely, though, that the Board of Supervisors will act quickly on the proposed amendment.

"Transportation, the movement of people, is a serious problem," said Raflo, whose committee is assigned to sift through the evidence and make a recommendation to the full board. "But location of the mall is also a serious problem and we intend to find solutions to both of them."

Representatives from both Lerner and Sunrise Development spoke in favor of a Rte. 7 site at a public hearing last month, saying that additional traffic pressure could be relieved with road improvements. But spokesmen from two county citizens groups denounced the amendment on the grounds that a shopping mall would lead to an explosion of commercial development along Rte. 7.

Two other companies, a group of investors called Camp Luckett Inc. and a group called Montouri Associates, have expressed an interest in building a mall at routes 28 and 625 as designated in the master plan, but neither firm appeared at the hearing.