This document discusses knowledge modelling techniques for traffic systems. It presents CommonKADS as a knowledge modelling methodology that can model the organizational structure, tasks, communications and knowledge of a system. It then discusses how CommonKADS has been applied to model knowledge in generic traffic systems and how MAS-CommonKADS extends it for multi-agent systems. Finally, it proposes using CommonKADS to model the identification and formation phases of dynamic virtual organizations for traffic control.