PURPOSES: The objective of this study is to find Percentile Speed( ) for Appraisal of Road Section with Recurring Congestion. METHODS : Percentile Speed( ) is determined by correlation analysis of CSI that proposed existing literature. and CSI(Consistency Service Index) is a index that subtract service fail frequency from 100 points, and service fail is defined as traffic situation is driving less than 80kph speed. In this study, We analyzed the highest correlation percentile speed associated with CSI. This speed is chosen as a delay decision speed. In order to verifying reliability, it performed a comparison with the previous method. RESULTS : As a result, 30 percentile speed( ) was decided as index speed for judgement of recurring congestion section, and through comparison with existing methods, we demonstrated that 30 percentile speed can be useful for judgement of recurring congestion section. CONCLUSIONS: This method to Determine recurring congestion section using the percentile speed( ) was proposed for the first time in this paper. This method can be applicated more quickly and easily than existing method for determining of recurring delay section .