Macroscopic Fundamental Diagram Validation for Collision Formation on Freeway Networks

Since the introduction of the macroscopic fundamental diagram (MFD), much work has been conducted using field data to estimate MFDs. However, despite some incorporation of collision occurrence into MFD assessment, there have not been any successful attempts to derive/validate the macroscopic fundamental diagram for collision formation. The objective of this research is to validate the MFD for full and partial lane closure due to collision formation. To accomplish such objective, the authors use microscopic collision and loop detector data from the Korea Expressway Corporation (KEC) and account for complete and partial lane closure due to collision in a similar manner to previous research in its incorporation of mixed traffic; collisions are considered moving bottlenecks in the same way as buses are in the previous research. Additionally, a principal component analysis is conducted on the mentioned traffic characteristics as well as lane closure times to investigate the relationships between MFDs and collision lane closures.