Increasing interest in sustainable development has underlined the importance of accessibility as a key indicator to assess public transport (PT) investments. In several developing countries, measurements of PT accessibility has been limited even though technical tools are available. In this work, a methodology for assessing the accessibility of an intra-city fixed-route PT service was developed and applied to the city of Nablus in Palestine. The primary objective was to develop a local index of public transport availability (Lipta) to reflect the availability levels of PT services on a zonal scale. The methodology adopts analytical methods using collective data and field surveys of PT frequency and characteristics. This study consolidates several other studies and integrates spatial and temporal components to produce a collective PT accessibility measure. The results showed that the Lipta provides a suitable methodology for measuring and assessing PT accessibility in urban areas. Its application to the case study showed that the zones in Nablus have various levels of PT accessibility, ranging from excellent to poor. Application of the Lipta provides a guide for transport planners and decision makers on where and how to improve PT services and coverage.