Bus stops create permanent bottleneck on the urban roadways within cities when passengers geton and off the bus and thereby causing decrease in curb lanes capacity. The study of bus stopsinfluencing on the capacity of signalized intersections has been attempted by several scholarsand researchers from both home and abroad. However, studies of bus stops impact on capacityof curb lanes are found to be very few. The objective of this study is to investigate thequantitative impacts of bus stops on capacity of curb lanes for the four categories of roadways inBeijing. Two types of bus stops such as bus bays and curbside bus stops impacts on capacity ofcurb lanes have been investigated for these four categories, namely expressways, major roads,minor roads and tertiary streets. Data have been collected at bus bays and curbside bus stopsrespectively for each of the four categories of roadways by video graphing or videotaping. New concepts of bus impact time occupancy rate or ratio and bus impact time (main parameter)have been introduced in the study. Relationships among bus deceleration time, bus accelerationtime, bus stop occupancy time (bus dwell time) and bus impact time have been established whenbuses maneuver to pull into and out of the bus stops, from field observation. A statisticalrelationship between bus impact times and bus arrival frequencies (volumes) has beenestablished using a Statistical Program for Social Sciences, (SPSS I3) for Windows. Three scenarios for collection of bus impact times and bus arrival tcequencies data have beenconsidered. Models of quantitative impacts of bus stops on capacity of curb lanes for the threescenarios were built and calibrated for the bus parameters (bus impact time and bus arrivalfrequency) using the collected data from fifty bus stops. After the analysis of bus parameters bythe employment of SPSS 13 for Windows software and calibration of the models, the followingfacts have been established: 1.Relationship between Bus Impact Time, T (bus main parameter) and Capacity of Curb Lane, C. 2.Statistical Correlation between Average Bus Impact Time, T and the Average Bus Arrival Frequency,λ. The models are very useful for the estimation of potential capacity of curb lanes under bus stopsand busesinfluence on the four categories of road in Beijing. Finally these models are veryuseful and can be used as the analysis tools by Engineers and Planners of the traffic and transportation professions to provide technically-sound advice to: (1) Public TransportOperators- for bus operation and urban bus management. (2) Department of Urban Planning andDesign. (3) Traffic Management Unit.