Aspects of the disclosure relate generally to controlling an autonomous vehicle in a variety of unique circumstances. These include adapting control strategies of the vehicle based on discrepancies between map data and sensor data obtained by the vehicle. These further include adapting position and routing strategies for the vehicle based on changes in the environment and traffic conditions. Other aspects of the disclosure relate to using vehicular sensor data to update hazard information on a centralized map database. Other aspects of the disclosure relate to using sensors independent of the vehicle to compensate for blind spots in the field of view of the vehicular sensors. Other aspects of the disclosure involve communication with other vehicles to indicate that the autonomous vehicle is not under human control, or to give signals to other vehicles about the intended behavior of the autonomous vehicle.