This paper presents a model of urban infrastructure decision-making wh
ich seeks to explain the complex social processes from the initial pro
blematization and enrolment to the final resolution prior to choice an
d action. The power theories of Callon and Crespi are used to form an
explanatory framework for these initial and final phases, and Social J
udgment Theory links the two. Case studies are presented to demonstrat
e the importance of problem definition and the necessity for the 'solu
tion' to fit normative social systemic structures if an excessive use
of power is to be avoided.