A recurring issue in the discourse about choice modelling is the role of consideration sets. Many scholars have proposed that consumers will follow a two-stage decision process. Others however have argued consideration set membership merely reflects utility and provides little additional information relative to observed choices. This paper argues that the role of the consideration set depends on the decision maker’s knowledge of the alternatives in the choice environment and his or her type of access to the alternatives.  It is proposed that two types of process operate to limit an initial large set of options to a smaller final choice set. One is a process of consideration set formation based on recalled attractiveness of options, the other an application of time and space based feasibility constraints. The paper presents a simulation analysis of the effects of knowledge and physical access on consideration and choice in the context of motorists' decisions where to refuel. It simulates a grid road network where motorist's access to petrol stations is constrained by the geographical location of the alternatives and the availability of network connections between them. In this hypothetical spatial environment the study simulates consideration and choice processes for refuelling options under different conditions of petrol station access and (non-spatial) station attractiveness.