The growth of traffic congestion on the streets is a major concern to every urban environment leading to high operation cost, loss of time, high delay and high travel time, increase in fuel consumption and in the emission of air pollutants. Donje Svetice and Planinska Street intersection is located in the City of Zagreb with high traffic congestion on peak hours leading to long queues on approaches. In order to curb the congestion on the approaches, functional efficiency optimization of intersection Donje Svetice and Planinska Street is taken as master thesis. The main objective of the study is to propose the design variants for the congestion of traffic on approaches after preliminary study of the intersection site and further design variants is analyzed in SIDRA for LOS (level of service), degree of saturation, control delay, signal phasing and movement timings. Design variants for intersection A (Donje Svetice and Planinska Street) are VA_I, VA_II and VA_III and for intersection B (Planinska, Square Volovcica and Ivanicgradska Street) is VB_I. Sensitivity analysis is carried out for the best variant for design period of 20 years. Network analysis is carried out to know the effect of minor intersection of adjacent place for the current volume of traffic as well as for the design period of 20 years. After the analysis of the intersections in SIDRA, the variant VA_III and VB_I is the most appropriate solution with lowest delay values and improved level of service for intersections. It eliminates the traffic congestion on the approach Planinska Street East.