This paper supplements the array of methods in urban policy discourse analysis by applying textometry to a corpus of planning documents. Textometry is a computer-assisted and systematic analysis of textual data. When applied to large corpora, the method can reveal contrasts that cannot readily be detected by non-instrumented human reading. By analysing numerous documents at a time we suggest a change in the scale of analysis of discourses so as to focus on massive transitions of discourse over time and on strong oppositions of discourses related to specific groups of actors. To exemplify the potential of such a method, the analysis developed here draws on a corpus of 36 French urban transport plans for the period 2000–2015. Our results display marked contrasts in discourses. They are primarily the result of general changes over time common to all cities. Paradoxically, the discourses become increasingly abstract at the same time as they highlight a purposive attitude. There are then contrasts that can be explained by more partisan rationales relating to the political persuasive strategy of the organizations producing the document.