Research on Operating Speed Characteristics of Highway

Regarded free-flow vehicle as the sample,applying statistical analysis software,testing data at observation sites were analyzed,and statistical parameters of speed samples under free flow condition and their cumulative frequency curves were achieved.K-S test and S-W test were used to test normal distribution for collected sample data.In order to obtain operating speed characteristic values,based on operating speed cumulative distribution curve,deviation was introduced and degrees of deviation under varied percentile operating speeds were analyzed. Accordingly,quantified standard for representing operating speed characteristics was determined. Results show that operating speed sample is normal distribution.85th percentile value of speed cumulative distribution curve should be used to represent the operating speed for geometric alignment design.The proposed conclusion can provide theoretical support for reasonable operating speed selection.