An apparatus is onboard a vehicle and in communication with sensors onboard the vehicle. The apparatus receives a maplet request identifying a request region; and, responsive to determining that the vehicle is within the request region, processes sensor data captured by sensors to generate a multi-sensor data stream corresponding to a road network segment. The apparatus identifies an observation corresponding to a traffic signal within the multi-sensor data stream; and generates a maplet based on the observation and the maplet request. Generating the maplet comprises using a predetermined data model and a predetermined data format corresponding to a traffic signal observation class to encode road data corresponding to the observation corresponding to the traffic signal. The apparatus provides the maplet such that a network apparatus receives the maplet. The network apparatus is configured to validate/update map data of a digital map representing the road network based on the maplet.