Research on Capacity Model for Large Signalized Roundabouts

In order to calculate the capacity of signalized roundabout, this paper establishes the corresponding calculation model. Based on gap acceptance theory, the model definites that the maximum number of vehicles on the approach that can be imported into the island is the roundabout capacity. At the same time, some related parameters (such as cycle, green time) are considered to impact on the model. At first, the paper analyses the difference of traffic flow characteristics between signalized roundabout and non-signalized roundabout, and according to the vehicles conflict traits, the movement process is divided into two stages. Then the new capacity model of signalized roundabout is put forward. Moreover analysis of the influence on capacity caused by different follow-up time, critical gap and green time are made, too. Finally, taking Changchun's signalized roundabout as an example, using the actual signal timing scheme and the data of the flow to verify the new capacity model,. It turns out that the results match the actual situation properly. In summary, a method of calculating the capacity of signalized roundabout is put forward, and proved to be practical in this paper.