Import Volume of Expressway's Merge Area Based on Double GamPDF

摘要

An expressway's merge area, which is the main cause of freeway traffic accidents, is located in the interchange of the mainline and the ramp. In order to study the traffic capacity of an expressway's merge area, this paper makes reference to related research results of scholars at home and abroad. Based on these results, this paper establishes a connection with the double Gamma probability density function (Double GamPDF) and the headway of the outside lane. In this way it can achieve a probability curve. Using the measured data, this study verifies the fitting effect can conclude that the curve is strongly fitting. Double GamPDF is introduced to integral and the model of the merging area's import volume can be determined by using the integration method. The data of the numbers of vehicles and the headway both in the main lane and a ramp in the Xi'an ring expressway are obtained through the survey. The survey data is used to compute the maximum number of import volume. Comparing with the measured import volume can prove that the calculation result is reliable and has high suitability.