Abstract:The paper presents a method for computing real time travel time reliability measure at different time of a day. Travel time distribution and travel time reliability measure over one day were investigated and analyzed on the basis of the measured travel time data of a signalized road.Analysis results show travel time distribution is skew and hysteretic, which denies the widely accepted assumption in this field that the travel time distribution is normal distribution. The relationship between reliability index, skewness of travel time distribution and the travel time reliability measure were also studied.