A traffic control board assembly as a self-contained unit is provided for mounting in an emergency response vehicle in a manner that accommodates deployment of a traffic control board above the top surface of the emergency response vehicle in any desired angular orientation about a vertical axis for visibility from any direction in relation to the emergency response vehicle. When docked, the top cover on the traffic board provides a weatherproof cover. Manual input and programmed control of a liftable rotation assembly on which the traffic board is mounted facilitate convenient and simple operation. A motion signal indicative of the emergency response vehicle moving can prevent deployment of the traffic control board and/or initiate returning it to a docked or stowed position.