A National Grid driver is being charged with vehicular homicide in connection with the tragic August 12, 2011 accident that, killed Westford, MA grandmother Xjaoyun Jiang and severely injured her family when a 2007 Case backhoe rolled off the trailer he was hauling and tumbled into Interstate 495 traffic.

According to Tim Connolly, a spokesman for Worcester District Attorney Joseph D. Early, Jr., Jeffrey Fischer, 50, of Coventry, will be arraigned Aug. 20.

Fischer, a National Grid manager, was road-testing a truck-and-trailer rig that had recently been flagged for safety concerns. Massachusetts state police said he lost control of the vehicle, causing the backhoe and a front-end loader to come loose and strike a minivan, killing 70-year-old Jiang. Her family has sued National Grid.