RALEIGH -- David N. Cox says he was merely exercising his right to petition the government, but a state Department of Transportation official has raised allegations that Cox committed a misdemeanor: practicing engineering without a license. Cox and his North Raleigh neighbors are lobbying city and state officials to add traffic signals at two intersections as part of a planned widening of Falls of Neuse Road. After an engineering consultant hired by the city said that the signals were not needed, Cox and the North Raleigh Coalition of Homeowners' Associations responded with a sophisticated analysis of their own.