In practice, the process of transportation planning is shaped by more than technical factors. This paper analyzes how different factors (demand, local conditions, financial, social, and political) have influenced all of the rapid transit projects in Ecuador over the past three decades by evaluating their relative significance on each system component (alignment, size, and technology). This research uses a multiple-case methodology including in-depth interviews with the senior members of the technical teams, as well as a survey component based on the analytic hierarchy process for quantification of the relative significance of the factors. The comparative analysis of projects shows five key results: (1) Each project was unique and external factors introduced a varying degree of complexity into each planning process; (2) The systems’ alignments and sizes were mostly driven by demand and local conditions (rational planning process); (3) The main factor driving technology selection has evolved over time from system demand to political (political bargaining approach); (4) Negative economic conditions had a large influence on the factors of all project components; (5) There is a lack of rational alternative evaluation and an absence of corresponding tools/guidelines in Ecuador. Nonetheless, several processes included practices that contributed to a more rational planning process: lifecycle cost analysis for the various technology alternatives, explicit decision-maker guidelines, transferring the demand risk to the private sector, and the use of multicriteria decision analysis. Implications for future planning efforts are discussed.