The background for this article is my final thesis “Minimetro, tramway or light railway”, elaborated atthe Institute of Technology and Social Sciences, unit of Technology Assessment, DTU, June 1995. It is made through my surprise over the debate which arose in the press following the Ørestad Consortium'schoice of a mini-metro in preference to a tramway or a light railway as Copenh agen's new cityline,three apparently very similar solutions but where each solution clearly had its proponents and o pponents.The debate was emotionally charged and the arguments forwarded concerned matters very di fferentto those presented by the Ørestad Consortium as being important. Following the decision in favour of the mini-metro and my own surprise concerning the links which developedamong the actors' arguments and actions, especially concerning things not mentioned in the debate,I have deconstructed the Ørestad Consortium's choice of the mini-metro. The article, therefore, isbased on the Ørestad Consortium's own presentation of the mini-metro in preference to the other twochoices, and subsequently an unravelling of the process which led to the Ørestad Consortium's choice.This unravelling considers the participant in the debate, hereafter 'the actors', and the choices which influencedthe requirements of the mini-metro. The background for the actors' power struggles lies in the rationalities. To unearth them would require adeeper dig. Transport- and town planning in Copenhagen express the ideologies, wishes and expect ationsof future society. The rationalities are reflected in the objectives of these plans. Rationalities are the actors' perception of problems and solutions attached to a specific distinct, in thisinstance transport planning in Copenhagen. Attached to a rationality is a relevant social group, which isa group of actors who have the same perception of objectives, for example with respect to transportplanning,, i.e. in other words a relevant social group is a group of actors who share the same rationality.The rationality, to which the actors, methods and structures (both institutions and infrastructures) are attached,is defined by the rationalities they hold. Rationalities are a partof society's discourses 1 and elementsof these discourses are made concrete in the rationality.