01336905

Component

https://doi.org/10.3141/2260-02

http://scholar.google.com...anzo&publication_year=2011

Macroscopic fundamental diagrams (MFDs), which relate the total time spent to the total distance traveled, are explored for freeway networks. It is proposed that these macrolevel relations should be observed if the data come from periods when all lanes on all links throughout the network are in either the congested or the uncongested regime. The theory pertains to freeway networks of any size, even when they are inhomogeneously congested and the data are variable in time. Analysis of vehicle trajectories from two freeway stretches of modest physical length supports this theory. Study further reveals that MFDs can be estimated with data from ordinary loop detectors, provided that every link in the network has at least one detector station and that the data are filtered to meet (approximately) the single-regime requirement. Detector data then confirm that well-defined MFDs exist for other freeway stretches and that the relations are reproducible across days. The results demonstrate that the stringent single-regime condition necessary to observe a freeway MFD does arise at times, even if only on shorter-length freeway stretches. The results also explain why previous efforts to observe freeway MFDs without filtering the data have been unsuccessful. Finally, the results suggest that policies to spread congestion evenly over a freeway network can be useful in maximizing the rate that trips are served.

01362482

11-0657

English

pp 8-15

2011

Transportation Research Record: Journal of the Transportation Research Board

9780309222976

Print

Figures (8) ; References (20)

Freeways; Loop detectors; Macroscopic traffic flow; Traffic congestion; Traffic data; Traffic flow; Traffic flow theory; Vehicle trajectories

Data filtering; Fundamental diagram

Highways; Operations and Traffic Management; I71: Traffic Theory

TRIS, TRB

Feb 17 2011 5:31PM

• Alternative Definitions of Passing Critical Gaps
• Comparing Heavy Vehicle and Passenger Car Lane-Changing Maneuvers on Arterial Roads and Freeways
• Development of Extreme Value Distribution Method for Estimation of Expressway Capacity
• Empirical Analysis of Effects of Automated Section Speed Enforcement System on Traffic Flow at Freeway Bottlenecks
• Empirical Study of Impact of Icy Roadway Surface Condition on Driver Car-Following Behavior
• Estimating Acceleration, Fuel Consumption, and Emissions from Macroscopic Traffic Flow Data
• Fundamental Diagram of Traffic Flow: New Identification Scheme and Further Evidence from Empirical Data
• General Newell Model and Related Second-Order Expressions
• Low-Rank Unscented Kalman Filter for Freeway Traffic Estimation Problems
• Modeling of Travel Time Variations on Urban Links in London
• Multiregime Sequential Risk-Taking Model of Car-Following Behavior: Specification, Calibration, and Sensitivity Analysis
• Real-Time Solution of Velocity-Based First-Order Continuum Traffic Model with Finite Element Method
• Traffic Flow Forecasting and Spatial Data Aggregation
• Use of Skew-Normal and Skew-t Distributions for Mixture Modeling of Freeway Speed Data
• Variations in Parameters of Time Headway Models According to Macroscopic Variables, Fundamental Diagram, and Exogenous Effects
• Wiedemann Revisited: New Trajectory Filtering Technique and Its Implications for Car-Following Modeling