A federal grand jury, widening its nine-month investigation of alleged bid rigging in state road projects in Northern Virginia, indicted four asphalt paving companies and three of the firms' officers yesterday on conspiracy and mail fraud charges.

The indictments were the first here since the Alexandria grand jury began last September to probe alleged price fixing among contractors in four suburban Washington counties where Virginia builds and maintains roads. An Alexandria company and four individuals entered preindictment guilty pleas to similar conspiracy charges late last month.

Named as corporate defendants yesterday on state contracts let in Fairfax, Loudoun and Prince William counties were Superior Paving Corp. of Centreville, Dominion Paving Inc. of Leesburg, General Paving Corp. of Manassas and E. Stewart Mitchell Inc. of Baltimore.

The three company officers indicted were identified as Barton S. Mitchell of Cockeysville, Md., president of the Mitchell and Superior firms; Bobby J. Surface of Cartharpin, Va., vice president of Superior, and Jack A. Mansergh of Hartly, Del., president of General.

Justice Department antitrust attorneys charged that since 1977, all seven defendants submitted "collusive, noncompetitive and rigged bids" to the Virginia Department of Highways and Transportation. The contractors predetermined contract winners by agreeing to submit intentionally high bids or withholding bids, the indictment alleged.

On March 6, 1979, the grand jury charged, contracts let by the state were illegally steered to Superior Paving for road repaving in Fairfax; to Dominion for two projects in Loudoun, and to General Paving for two projects in Prince William. Dollar amounts of the projects were not specified.

In separate counts, Superior, Dominion and General and their officers also were charged with mail fraud. The grand jury said the state had mailed checks totaling more than a half-million dollars in July 1979 to each company after the defendants swore in affidavits they had not colluded to rig bids.

The maximum penalty for conspiracy in restraint of interstate trade is three years in prison and a $100,000 fine for individuals and a $1 million fine for a corporation. Mail fraud is punishable by five years' imprisonment and a $10,000 fine.

On April 29 in U.S. District Court, the Newton Asphalt Co. Inc. of Alexandria, the company's chief engineer, and executives of Tri-County Asphalt Co. of Leesburg and Sam Finley Inc., a division of Atlanta-based Ashland Warren Co., pleaded guilty to a charge they had engaged in similar bid rigging. Each of those defendants has been cooperating with the grand jury, according to statements made in court at the time.

The Tri-County firm is owned by Dominion Paving Inc., formerly known as Hazel Paving Inc. of Fairfax County, yesterday's indictment said.

The latest charges are an outgrowth of a widespread federal bid rigging investigation in Virginia and 16 other states. Justice antitrust attorneys began probing state paving contracts in Virginia in the fall of 1979 after Richmond airport officials questioned the similarity of bids submitted for a runway paving project.

A parallel investigation by the Virginia state attorney general's office resulted in an $800,000 civil settlement paid by Ashland-Warren.