Procedures for planning, conceiving and designing roads represents complex urban – traffic tasks. Considering that each type of traffic requires corresponding traffic infrastructure, everything is based on exhaustive traffic analyses. In these analyses, use of microsimulation computer program, makes it much easier for us, which can help us to determine does the network traffic satisfy the current or future traffic demand. In the implementation of planning or designing any solution, it is necessary to analyze all areas and compare certain variants, so that in the end, the most favourable solution gives satisfactory results when evaluating the functionality of traffic flow. The aim of this graduation thesis is implementation of the analysis to optimize exit lane length of high – speed city road, using traffic simulation. Then chosen analysis location is Southern Osijek detour, and observed exit lanes are located at the junctions Trpimirova and Frigis. Junctions were chosen due to their proximity to industrial and business zones towards which a lot of vehicles travel. For the analysis of different scenarios, the computer program PTV VISSIM 6.0. was used in the thesis. Collected data from field measurements of traffic counts in the rush hours of 7 – 8 AM and 3 – 4 PM, as well as vehicle speed recording by radar, where used as input data for the model of the existing project solution of the exit lane. Using simulation model, analyzes were curried out with different traffic loads and speeds and the output results were obtained. Based on the final results, project recommendations were given in the conclusion about exit lane optimal length of the high – speed city road.