Exploring the Relationship between Heterogeneity of Vehicle Distribution and the Macroscopic Fundamental Diagram under Segment Disruption Conditions

:The framework of a well-defined Macroscopic Fundamental Diagram (MFD) relating network-wide flow and density was proposed under the homogeneity assumption that congestion is distributed evenly which is not universal in practice. This study aims to explore deep details of the relation between heterogeneity of vehicle distribution and the MFD under segment disruption conditions. By plotting MFDs and calculating variance, kurtosis and skewness of segment traffic density for different network structures, details of the relation are revealed. Results show that under segment disruption conditions, if the network flow reaches the maximum level at the same density for different network structures, a negative correlation between heterogeneity of vehicle distribution and maximum flow can be established. Similar relation can be observed under other states except free flow state. Nevertheless, heavy congestion may affect this relation because of spillback. Overall, the results are significant for traffic control to maintain networks at a high-efficiency level under segment disruption conditions.