This paper addresses the evaluation of several procedures for delimiting service areas of urban transport facilities and computing the served population. To this end, detailed data of a local case study and a geographical information system are used. Adopting two different georeferencing methods and two spatial metrics, the tested approaches reveal disparate results and errors, which allow to appreciate the advantages and limitations of each one. It is expected that the conclusions will contribute to increase the accuracy of analysis focused to urban public transport planning and decision taking.