This paper presents a study of drivers' gap acceptance behavior at an uncontrolled intersection. A 4-leg uncontrolled intersection located in a semi-urban area of Ahmedabad, Gujarat was selected to study the gap acceptance behavior of drivers. Video recording technique was adopted for data collection and analysis. Various available methods are used to calculate the critical gap for minor road passing and right turn movements. Gaps are analyzed for three different vehicle types. A comparison is made between the various existing methods of critical gap detection and their critical analysis is presented. The result shows that except for the behavior elimination approach, all other methods cannot provide the real scenario of the critical gap under mixed traffic conditions because all these methods are developed for homogeneous traffic conditions.