The Justice Department's far-ranging investigation into bid-rigging in highway construction, water and sewer projects and electrical contracts is continuing to expand.

The highway construction portion of the investigation has led to 237 criminal prosecutions involving 217 firms and 232 individuals in 17 states, according to department spokesman Mark Sheehan. That part of the probe began in December, 1979.

As of last month, courts had imposed fines totaling $49 million and aggregate prison sentences of 46 years. Federal grand juries looking into highway bid-rigging are now sitting in 22 states.

The year-long investigation of bid-rigging in water and sewer projects has led to eight criminal prosecutions of six corporations and nine individuals in North and South Carolina. Further indictments are expected from federal grand juries in eight states.

The investigation into bid-rigging in electrical contracting has been going on only since last May, but the department has already begun 11 prosecutions against 22 corporations and 22 individuals in Washington state, North Carolina, Indiana and Pennsylvania. And grand juries are continuing to review evidence in five states.

One of the largest cases involves three companies that allegedly submitted bids of more than $100 million each in connection with electrical work for a nuclear reactor project in Washington state. IN THE RUNNING . . . Several people have been mentioned as possible replacements for Carol Dinkins, who recently stepped down as assistant attorney general in charge of the Lands and Natural Resources Division to return home to Houston. One is F. Henry Habicht II, acting head of the division. The others are David Kennedy, a lawyer from Sheridan, Wyo., and Thomas Hookano, a Sacramento lawyer who once headed the conservative Pacific Legal Foundation. INFORMATION . . . A recent study by the General Accounting Office has found that the department's responses to requests under the Freedom of Information Act generally take many times the 10-day limit stipulated by law.

Under the law, which governs public access to government information, the department is required to locate and analyze the requested files, determine whether the information is public and, if it is public, provide the requested information--all within 10 days.

But the GAO found that in cases where information was found in department files, an average of nine months elapsed before the request was answered.

The GAO blamed the delays on the decentralized records kept by Justice, the volume of the requested material, the time required to screen sensitive material and substantial backlogs. For example, the study found that as of Sept. 30, the Civil Rights Division had a backlog of 360 requests for information.

The study, which focused on six units within Justice--the FBI; the Criminal, Civil, Civil Rights and Antitrust Divisions; and the Office of Information and Privacy--found that shorter and simpler requests for information are processed more rapidly and receive priority over longer and more complex cases.

The GAO found that the FBI tends to expedite cases that could involve danger to life or property, while the Office of Information and Privacy said it expedites requests from the news media. NAMES AND FACES . . . Two new regional directors have been named to the Community Relations Service, a branch of the department that assists communities in resolving race-related problems. They are Tommie C. Jones, who will head the Northeast regional office, and Jesse Taylor, who will head the Midwest region office.