Citation

Xu G, Yu Z, Gayah VV. Transp. Res. Rec. 2020; 2674(9): 933-947.

Copyright

(Copyright © 2020, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

10.1177/0361198120933274

PMID

unavailable

Abstract

Network macroscopic fundamental diagrams (MFDs) have recently been shown to exist in real-world urban traffic networks. The existence of an MFD facilitates the modeling of urban traffic network dynamics at a regional level, which can be used to identify and refine large-scale network-wide control strategies. To be useful, MFD-based modeling frameworks require an estimate of the functional form of a network's MFD. Analytical methods have been proposed to estimate a network's MFD by abstracting the network as a single ring-road or corridor and modeling the flow-density relationship on that simplified element. However, these existing methods cannot account for the impact of turning traffic, as only a single corridor is considered. This paper proposes a method to estimate a network's MFD when vehicles are allowed to turn into or out of a corridor. A two-ring abstraction is first used to analyze how turning will affect vehicle travel in a more general network, and then the model is further approximated using a single ring-road or corridor. This approximation is useful as it facilitates the application of existing variational theory-based methods (the stochastic method of cuts) to estimate the flow-density relationship on the corridor, while accounting for the stochastic nature of turning.

RESULTS of the approximation compared with a more realistic simulation that includes features that cannot be captured using variational theory--such as internal origins and destinations--suggest that this approximation works to estimate a network's MFD when turning traffic is present.

Language: en