Dynamic cost functions and freight transport modal split evolution

• Modal split evolves in a sequence of time periods with different characteristics.
• The distribution of dynamic cost functions determines the modal split evolution.
• Modal split evolution is stable if users react slowly to transport cost changes.
• Similarity of the dynamic cost functions fosters a stable modal split evolution.

The paper studies the characteristics of the evolution over time of modal split for a transport system in which various modes compete with each other and face the freight flow increase in different ways. It is shown that the modal split evolution is constituted by a sequence of time periods, in each of which the dynamic characteristics of the system are different. An equilibrium, stable or unstable, is reached after a transition phase, whose length depends on the characteristics of the system, and in some cases exceeds the length of the period, so that an equilibrium is not reached.