The objective of this Diploma Thesis is the investigation of the impacts of a traffic incident at a central urban road network in Athens and its management, through the implementation of alternative traffic control scenarios, using the microscopic traffic simulation software package, pt Vissim. In order to evaluate the results, travel time, delays, number of stops per vehicle and length of queue were defined as measures of operational performance. The first scenario relates to the intervention on traffic signal programs of the road axis in which the incident occurs. The second scenario involves the guidance of drivers to an alternative route by information provided through a Variable Message Sign. The application of these models to the particular traffic data indicates that traffic conditions are significantly improved during the first scenario, whereas during the second scenario the deterioration in the roads of the alternative route is more serious than the improvement succeeded.