One variation of a method for updating a localization map for a fleet of autonomous vehicles includes: selecting a set of roads including a first subset of road segments associated with existing incomplete scan data and a second subset of road segments associated with a monitoring request from an external entity; during a passenger period at the autonomous vehicle, autonomously transporting passengers according to a series of ride requests; during a mapping period succeeding the passenger period at the autonomous vehicle, autonomously navigating along the set of road segments, recording a first series of scan data representing surfaces proximal the first subset of road segments, and recording a second series of scan data representing surfaces proximal the second subset of road segments; updating the localization map based on the first series of scan data; and serving the second series of scan data to the external entity.