This paper describes the applications of traffic simulation on the big-size urban networks under development of transport infrastructure and intelligent transportation system (ITS). Research, experiments, simulation and design were performed on the city network Sochi where will take place mega event - the winter Olympic Games in 2014. The following conceptual principles are presented as tools for effective solution of traffic problems: monitoring parameters of traffic flow on an urban network; determination of level of service and estimation of congestion conditions; traffic simulation on urban network and estimation of specific traffic scenarios, the forecast of the system effectiveness. Microscopic traffic simulation has provided important data on an estimation of road capacity, velocity, trip time, and detection of congestion reasons.