Transportation planners and public transport operators alike have become increasingly aware of the need to diffuse the concentration of the peak period travel. Differentiated pricing is one possible method to even out the demand and reduce peak load requirement. An evaluation of the potential effectiveness of strategies directed to flatten the demand distribution requires an understanding of the underlying factors that drive travel behavior (e.g., time-shifting, route change, mode change) with regard to price and service. In this paper, we present a Passenger Railway Network Simulation model with the intention of linking supply and demand. The objective is to evaluate the differentiated pricing impact on the passenger travel behavior, and consequently on the overall network performance, both financially and operationally. This paper focuses on the design and modeling approach of the Travel Behavior Model.