The transport system is embedded in the broader social, economic and environmental systems. From a policy analysis perspective, the transport system, with its components and their interrelations, could be understood as an abstract conceptual model and as a web of nodes that are interlinked. This web‐model of the transport system illustrates well that, when tackling one of the nodes, this is not an isolated phenomenon but other nodes are affected as well, via the linkages between these nodes. At the more or less blurred borderlines, other systems (energy system, land‐use patterns and economic system) are attached and interact. Planners and researchers know some of these nodes, some nodes are anticipated but not exactly known, and other nodes are completely unknown. Remaining with this “web of nodes”‐model, a policy intervention in the transport sector directly affects at least one, maybe several of these nodes. At the same time, a number of other nodes can be affected indirectly, via the linkages. The directly and indirectly affected ones start swinging and influencing each other, potentially generating rebound effects. The model illustrates that a policy intervention can lead to widely ranging effects, and some of them may only become visible after the measure was implemented. Many of these nodes and linkages are known and well described. Others are known to exist but not sufficiently conceptualised, and a third group of nodes and linkages are completely unknown. This widely corresponds with the categories, “unknown unknowns”, “known unknowns” and “knowns” illustrated above.