Estimating critical gap and follow-up Time estimation for U-Turn movement by using linear and multiple Regression

Gap and follow-up time are two important parameters in un-signalized intersection and capacity calculation. Due to great capacity and high velocity of conflicting traffic on important urban roads , applying U-Turn action needs proper gap and follow-up time. Thus, U-Turn action always encounters safety and efficiency problems. Many methods have been introduced for calculating critical gap like Logit, Raff, Maximum Likelihood (MLE), and HCM methods. In this paper, data were collected from four opening median located on arterial roads in Rasht, a follow-up time and the critical gap model were developed by linear multiple regression analysis. Results showed that increases vehicle total delay time in U-Turn action reduces critical gap and increases vehicle speed in conflicting traffic areas. Also, based on the conclusions, increasing the ratio of follow–up time to critical gap reduces of U-Turn in opening medians.