You must to build an information model of the road network of the city, to develop an estimation algorithm of parameters of it using modern and long-term observations of road traffic characteristics. Identify areas with increased risk of traffic jam problem (for different periods of time, seasons). Simulate different scenarios for optimization of traffic management system to reduce the risk of traffic jam problem.
But always there is a problem of accidents (road traffic accidents, a breakthrough of a heating on road, road repair, etc.).