Evaluating road geometric design consistency is crucial for ensuring highway safety. The goal of geometric design consistency studies is to locate the inconsistent portions of highways so that suggestions for improvement can be made. As per studies, geometric design consistency measures are categorized based on operating speed, vehicle stability, driver workload, and alignment indices. In this study, geometric design consistency is evaluated based on the operating speed of vehicles on a two-lane state highway passing through rolling terrain. Horizontal curves of varying radii ranging from 23 to 50 m and listed as black spot locations by previous studies were considered for the study. Data on the operating speed of vehicles passing the approaching tangent and midpoint of the curve and their geometric parameters, such as curve length, gradient, superelevation, and minimum sight distance, were collected through field surveys. The 85th percentile speed of each vehicle category is then plotted against the curve radius. Pearson correlation analysis was done to study the geometric consistency by correlating the operating speed with the geometric parameters and determining their significance. Based on this, the operating speed reduction prediction model is developed by linear multiple linear regression at a 95% confidence interval using SPSS software, which is then validated in terms of mean absolute deviation (MAD) and root mean square error (RMSE) values. The model developed is further used for geometric design consistency evaluation.