Traffic Congestion is a multi-billion dollar national problem and worsening every year with population growth and increase in freight traffic. We present a model for realistic simulation studies to mitigate congestion in urban areas using dynamic congestion pricing on express toll lanes. Specifically, we identify and address the design issues needed to develop a real time event driven sensor web observing system for traffic monitoring that provides dynamic congestion pricing. To assess the feasibility of this sensor web system, we are in the process of conducting simulation studies based on real data for various system configurations to validate the mitigating impact of dynamic congestion pricing on intermodal freight flow to and from the ports in urban areas. In this paper, we focus on freight flow into the Baltimore corridor from its ports.