Job accessibility is an important factor of urban transition as it influences the residential location choices made by inhabitants and the location of new residential development projects by developers. Spatial interaction models allow for the assessment of the urban transition potential of localities based on the accessibility of various urban activities. In this way they provide valuable information for Smart city governance. This paper presents the Job Accessibility Model (JAM) which is based on principles of spatial interaction. JAM estimates the potential accessibility of individual locations to job activities in the Prague Functional Urban Area (Prague FUA). The job accessibilities are based on job activity distribution and transportation network data. Up until now, spatial interaction modelling in the Czech Republic has been limited by the quality of data on the spatial distribution of jobs. This paper presents a new approach that benefits from highly disaggregated data on buildings and their use. This approach may significantly improve the validity and reliability of urban models. The paper illustrates the evaluation of the planned road network improvement in terms of job accessibility. The paper concludes with a discussion on the potential use of improved data in urban modelling.