Despite evidence of driver error, no criminal charges will be filed in connection with the Aug. 26 crash in Frederick County of a racetrack commuter bus that left the driver and five passengers from the Baltimore area dead, Maryland state police announced yesterday.

After a six-week investigation that included a reconstruction of the accident and interviews with survivors, state police Sgt. Bill Tower said that George Whalan Brown was driving the bus at an excessive speed under rainy conditions. Police said the bus' speedometer was not functional at the time of the accident; witnesses indicated that the bus was traveling at 65 to 80 miles an hour.

The investigation also disclosed that between 1956 and 1975, Brown received 22 traffic citations, including 13 for speeding, and his license was suspended three times for up to 30 days. National Transportation Safety Board investigator Claude Harris said that under federal regulations, Brown was prohibited from operating a commercial vehicle because of a diagnosed diabetic condition, but that officials of the bus company were unaware that Brown was taking the medication.

An autopsy disclosed that Brown also was taking several other medications, including a diuretic to counter hypertension, an antibiotic and three antirejection drugs in connection with two kidney transplants, the most recent one six months ago.

Despite the ruling that the accident resulted from "driver error," Tower said, the state's attorney's office in Frederick County had concluded there is "insufficient evidence to warrant charges of criminal negligence" against the bus company.

Civil lawsuits totaling $8 million have been filed against the Baltimore Motor Coach Co. by families of accident victims. The company has asked for dismissal of the suits in a petition for Chapter 11 bankruptcy reorganization.

The accident occurred on a rain-slick I-70 bridge over the Monocacy River east of Frederick as the bus was headed toward Charles Town, W.Va. As the bus approached the bridge, survivors said, Brown apparently braked to avoid hitting the car in front of it and the bus began to fishtail, striking a guardrail and ricocheting across the two westbound lanes