Following a four-month FBI investigation, a federal grand jury here is investigating an alleged pattern of favoritism in the handling by D.C. Superior Court Judge Robert H. Campbell of overweight truck violations against a large Washington area excavation firm, The Washington Post has learned.

Sources said investigators now are focusing on a recent two-year period during which Campbell repeatedly suspended or revoked fines for hundreds of overweight truck tickets issued to Excavation Construction Inc. (ECI).

In the last month, ECI officials have been called to testify before a grand jury and records of the firm have been subpoenaed, sources said.

Law enforcement authorities have estimated that as many as 1,400 tickets - each carrying fines of $100 to $300 - may have been issued to ECI between October 1975 and May 1977, although the company repeatedly acknowledged the violations, court records in dicate that Campbell consistently suspended imposition of fines. On some occasions, he disposed of in one day as many as 121 tickets issued to ECI.

The Post reported last April that Campbell was under investigation by the city's judicial tenure commission for alleged judicial misconduct in his handling of traffic tickets for firms with large fleets of vehicles. The panel, which can remove, publicly reprimand or otherwise discipline an errant judge, is reportedly continuing its separate broader investigation.

Campbell, 56, former chief of the law enforcement division of the D.C. corporation counsel's office, was appointed to the Superior Court bench in 1972. Campbell has said that during the past five years he has spent 22 months as the judge assigned to traffic court and has handled about 100,000 cases.

The judge's critics have claimed that while in traffic court, Campbell would frequently impose harsh penalties - including fines and jail terms - on individual defendants but was more lenient in cases involving large companies who appeared before him with large number of traffic tickets.

Campbell, who presided yesterday over preliminary hearings in the normal wide range of criminal cases that come before a local judge here, could not be reached for comment late yesterday.

Excavation Construction is one of the area's largest excavation and construction firms, having handled $60.1 million in contracts for Metro construction and other projects in 1977, according to an engineering trade magazine. Its president is John W. Lyon, who worked as general manager of the city's largest parking firm - Parking Management Inc (PMI) - at the same time he was building up his construction business over the past decade.

ECI is also the target of another federal probe. A wide-ranging investigation of labor racketeering by the U.S. attorney's office Baltimore focused on allegations that officers of the firm traded favors with Teamsters officials in return for concessions from the union. That investigation became known publicly when one of the subpoenaed witnesses was slain in Rockville last May.

An attorney for the firm, Paul M. Rhodes, said yesterday afternoon he was aware of the separate grand jury investigation into the alleged Campbell-Excavation Construction relationship. However, he said he would not have any comment since he was unable to reach either Lyon or Excavation Construction associate Larry Campbell, who is no relation to the judge.

Investigators are aware of Judge Campbell's reputation within the local courthouse for alleged favoritism and have reviewed court records in an attempt to compare Campbell's sentencing decisions in cases involving individuals and businesses, sources said.

In May 1977, an independent study conducted by the D.C. Bar Jail Project showed that during November and December 1976 large numbers of people were detained at the D.C. jail on traffic charges because they were unable to immediately post a bond when they appeared in court. Judge Campbell presided in traffic court for six of the eight weeks examined by the Jail Project.

The study showed that in 69 of 125 traffic court cases studies, the defendants - none of whom were represented by lawyers - remained in the jail for an average of 11 days. Judges in traffic court can set bonds to assure the defendant's appearance in court on the scheduled trial date.

As a result of the project's findings, Harold H. Greene, then chief judge of the Superior Court, agreed to allow court funds to be used to appoint lawyers for traffic court defendants who are unable to post bond but could not afford to hire an attorney.

Some lawyers have complained that Campbell was at times unusually abusive of some individuals who appeared before him in traffic court.

For example, one lawyer said he witnessed an incident in court shortly before Christmas in December 1976 when Campbell told a defendant that he would be released from the court's custody if the man could name "all of Santa Claus' reindeer."

The defendant, an insurance company employee, had been arrested after D.C. police stopped him for a minor traffic violation and then discovered the man's driver's license had been revoked, the witness said.

Campbell ordered the man to post a $200 money bond for his release prior to trial, the witness said. When the man said he could not pay the money immediately, Campbell said he would release him if the defendant named the reindeer, the witness said. According to the witness, Campbell told the man "one of them is not Rudolph."

As the defendant, who was described by the witness as "well-dressed" and "articulate" began to recite some names, Campbell began to laugh and then left the courtroom.

"It was the most degrading thing I've ever witnessed in a courtroom," the witness said.

The man was released from court that day on his personal recognizance, the witness said!

Henry A. Berliner Jr., chairman of the D.C. Commission of Judicial Disabilities and Tenure, confirmed last April that the panel was investigating the local traffic court, as well as the small claims and landlord tenant divisions of the Superior Court. He refused to comment further on the investigation.

At that time, it was learned that the commission was particularly interested in several traffic cases that came before Judge Campbell that involved large numbers of parking tickets issued to an Arlington messenger firm.

It was also learned that the commission had questioned Campbell privately about allegations of judicial misconduct in connection with the handling of traffic tickets. The commission also discussed its initial findings with law enforcement authorities.

When asked yesterday if the commission's investigation was continuing and whether it was now focused on Judge Campbell's activities, Berliner said, "I will absolutely not comment on that."

In an interview last March, Campbell strongly denied that he ever gave favorable treatment to corporations while he was a judge in traffic court.

Campbell said then that he had never jailed any defendant in connection with traffic tickets. When he has determined that some violators are "scofflaws," Campbell said, he has required them to pay fines. He also said at the time he had no recollection of any specific cases involving Excavation Construction.

At that time, Campbell described traffic court as "a nuisance" and said the court has never been "fully staffed." Although he has spent many months on the traffic court bench, Campbell said during that interview "I don't like it. I despise it. I don't know anyone who likes" it.

Since the passage by Congress of a law in the early 1970s, the huge trucks that carry dirt and other materials away from construction sites in the District can get what are known as "heavy tags" to allow them to legally carry up to 65,000 pounds at a time.

The overweight permits cost $680 per vehicle per year, with the express purpose of the high fee being to compensate the District for damage to roads and other highway structures by the heavily loaded trucks.

D.C. Department of Transportation records show that for part of 1975 and all of 1976, Excavation Construction neglected to purchase the $680 annual permits that would have allowed the firms fleet of about 70 vehicles to carry overweight loads.

The highway department has two sets of portable scales that are operated around town by crews of employes who weigh large trucks, usually at random, in an effort to enforce the overweight laws. The scale crews are accompanied by a police officers who issues tickets to drivers whose trucks are found to be in violation of the weight limits, authorities said.

It is known that the crews often "stake out" major construction sites to monitor the overweight problem.

The maximun penalty for an overweight ticket is a $300 fine or 10 days in jail or both, according to law enforcement authorities. However, when a ticket is issued, the violator can forfeit $100 collateral and thus avoid an apperance in traffic court.

If the violator elects to appear in court, no collateral has to be posted, officials said. Once the violator appears in court, the penalty imposed is up to the discretion of the judge.

It is not unusual that a judge would impose a fine substantially lower than $100 if the violator appears in court.

A review of available official Superior Court records by The Post showed that from October 1975 to May 1977 Campbell handled at least 550 tickets issued in the name of Excavation Construction.

The records show that Campbell suspended fines in all of those cases, sometimes against the recommendation of the assistant corporation counsel handling the case.

In one instance available before that time period, Campbell did fine the firm $210 for 14 overweight tickets in February 1975.

In March 1978, when ECI was up before another judge, D.C. Superior Court Judge George D. Neilson, with a total of 286 tickets, Neilson fined them $25 for each ticket, for a total of $7,150.

Although a review of court records by The Post indicates Judge Campbell handled 564 overweight tickets involving Excavation Construction, persons more familiar with the firm's corporate structure and practices of the trucking industry said substantially more tickets are believed to be involved.

The various investigations into Campbell's handling of traffic court matters have been hampered by the difficulty of retrieving complete records investigators said. As many as 2,000 cases a week can pass through traffic court here, and records of dispositions are often sketchy and files are sometimes incomplete.

Excavation Construction Inc. was organized in 1965, with John Lyon assuming the presidency in 1969, according to corporate records. A year later, two other corporations headed by Lyon - Overland Construction Inc. of Maryland and Paving Construction Inc. of D.C. - merged into Excavation Costruction.