constant describing the object type, see RoadObjectType. Available road object types are:
RoadObjectType.TUNNEL
RoadObjectType.COUNTRY_BORDER_CROSSING
RoadObjectType.TOLL_COLLECTION
RoadObjectType.REST_STOP
RoadObjectType.RESTRICTED_AREA
RoadObjectType.BRIDGE
RoadObjectType.INCIDENT
RoadObjectType.CUSTOM
RoadObjectType.IC
RoadObjectType.JCT