This study presents the behaviour of vehicles at mid-block median U-turn openings in multi-lane divided urban roads based on gap acceptance in Egypt. Most of the median openings in Egypt are uncontrolled. In this study, models are proposed for calculating U-turn capacity using both field and gap acceptance approaches. This study estimates the critical gap or lag, accepted gaps, and vehicle merging time in U-turn opening. The capacity of median openings mainly depends on the critical gap and follow-up time of U-turn vehicles. Hence, a thorough investigation into the gap acceptance behaviour of U-turn vehicles was carried out. A field approach depends on data collection and was performed on eight different sites in El-Obour and Benha cities in Egypt. Data collection was done during peak hours using a video recording technique at the selected sections. Sections were chosen to be free from gradients, curves, and on-street parking. In addition, Eight factors were considered; five related to the u-turning vehicle (age, gender, vehicle type, queue length, and wait time); three related to the conflicting traffic (gap size, speed, and vehicle type). The results showed that those factors had an effect on the decision in the following descending order: gap size, speed, wait time, conflicting vehicle type, queue time, gender, u-turning vehicle type, and age. The significant factors included gap size and speed. Both field and gap acceptance approaches were used to estimate the capacity of U-turn movement. The field approach was done using regression analysis