WILLIAMSBURG - A cyclist was killed overnight in the Williamsburg section of Brooklyn and commuters who rely on their bicycles say they are concerned for their safety. Police say the rider was hit by a tractor-trailer near Morgan Avenue and Meserole Street as the truck made a right turn. The death marks the third time since August that a bicyclist has been fatally struck in the same area. In the wake of the incidents, Neighbors Allied for Good Growth, a local advocacy group, has asked city officials to make street signs clearer. According to its website, the Department of Transportation defines bicycles as vehicles, meaning riders must ride with traffic and obey traffic signals. Cyclist killed in hit-and-run in Williamsburg