A 46-year-old man was killed in a single-vehicle crash Thursday night on the Garden State Parkway in Monmouth County, authorities said. Olair Alves Da Silva was driving north near milepost 108 in Tinton Falls around 9:45 p.m. when he veered off the local lanes to the left, across a grass median and struck a metal post, State Police said. His car then overturned into the northbound express lanes and slammed into a guard rail, throwing Da Silva from the vehicle. Da Silva, of Deal, was pronounced dead at the scene. There were no passengers in the vehicle. The crash remains under investigation, po…