Road geometric design in Ethiopia is made based on the design speed concept in which the design speed of the most restrictive geometric element is used as the design speed for a long road segment. Previous studies reported that the design speed by itself may not ensure geometric design consistency. Hence, the aim of this thesis was developing operating speed prediction models for both horizontal curves and approaching tangent sections and evaluating the design consistency of selected road segments from Dejen to Debre Markos. The data analysis showed that, on horizontal curves, the mean of the 85th percentile operating speed were not statistically different from the mean design speed. Among candidate independent variables, tangent length; curve radius and curve length were significant for entry into the operating speed prediction model for horizontal curves while grade, tangent length and radius of the following curve were significant predicators for operating speed prediction model on approaching tangents. Design consistency evaluation of 29 road sections were performed using the design consistency evaluation criteria for successive and single elements. Consistency evaluation for successive element showed that, 15 sections are in good consistency, 10 sections are in fair consistency and the remaining 4 sections are poor in design consistency. While consistency evaluation for single element showed that 2 sections were poor in design consistency based on the criteria for single element. KEYWORDS: Successive Element, 85th percentile speed, Design Speed, Ethiopia, Horizontal Curve