Cause of Construction Accident Still Unknown, Investigators Say

Investigators said yesterday they have not yet determined the cause of Tuesday's accident at the MBTA Red Line Extension Project in Harvard Square which killed a construction worker

John H Kelly Jr., project superintendant for the Perini Corporation, was killed when a small crane overturned, hitting him on the head with its boom

Officials from Perini the MBTA, the Massachusetts Department of Labor and Industry and the federal Occupational Health and Safety Administration (OSHA) are independently trying to determine what caused the crane to turn over.

Perini employees at the scene Tuesday said the crane was lowering a large empty bucket used to transport materials to and from street level when the accident occurred. Kelly-apparently was guiding the operation and had his back turned to the crane.

Tuesday's accident has not caused additional concern among Harvard officials over the safety of students and employees walking through the Square, Edward Lasham, director of external projects for the University, said yesterday. He added that the Perini Corporation has "a pretty remarkable safety record" considering the heavy traffic in the Square and the complexity of the project. P>Vince Farrell, area engineer for the MBTA, said. "The safety record of the Harvard Square job up until this time has been exemplary. "He said it is a general practice to make sure pedestrians stay clear of any possible danger, and the MBTA employs six policemen at the Harvard Square site.

"Whenever we make a [crane] lift over the street, we stop both traffic and pedestrians; it happens every day." Farrell said.

Kelly's death marked the third fatality on the Red Line project since it began in 1979 Last August, a tunnel caved in near Porter Square, killing a construction worker. Approximately 18 months ago, a worker was killed when the acctyline torch he was using blew up near Davis Square in Somerville. Neither of these workers was employed by the Perini Corporation.

The five-year project, due to be completed on 1985, will extend the Red Line through Porter and Davis Squares, ending at the Alewife station in North Cambridge.