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Title:

DUAL MODE BEHAVIOR OF FREEWAY TRAFFIC

Accession Number:

00227928

Record Type:

Component

Abstract:

ANALYSIS OF TRAFFIC FLOW DATA FROM THE JOHN C. LODGE FREEWAY IN DETROIT INDICATES THAT FLOW CAN BE CATEGORIZED INTO TWO DISTINCT MODES: (1) STEADY FLOW, WHERE THE USUAL LINEAR AND PARABOLIC RELATIONS BETWEEN DENSITY, FLOW RATE, AND SPEED APPLY, AND (2) AN OSCILLATORY MODE, IN WHICH SPEED AND DENSITY EXHIBIT OUT-OF-PHASE PERIODICITIES WHEN PLOTTED AS A FUNCTION OF TIME. THE SYSTEM SWITCHES FROM ONE MODE OF FLOW TO THE OTHER WHEN OPERATION IS NEAR THE VERTEX OF THE LANE OCCUPANCY-FLOW RATE PARABOLA. THE LOCATION OF THIS VERTEX IS BETWEEN 13.1 AND 16.1 PERCENT LANE OCCUPANCY ON THE CENTER AND MEDIAN LANES, AND BETWEEN 12.4 AND 18.1 PERCENT ON THE CURB LANE. THE RECOVERY FROM THE OSCILLATORY MODE IS RAPID WHENEVER LANE OCCUPANCY FALLS BELOW THE CRITICAL VALUE. THE FREQUENCY OF THE OSCILLATION WAS FOUND TO BE 1/4 CYCLE PER MINUTE FROM CALCULATION OF THE AUTOCORRELATION AND POWER DENSITY SPECTRUM OF THE OSCILLATORY WAVEFORMS. BY CROSS- CORRELATION OF THE WAVEFORMS MEASURED AT PAIRS OF LOCATIONS, IT WAS DETERMINED THAT THE ONSET OF THE OSCILLATORY MODE PROPAGATES UPSTREAM AT A RATE OF 16 MPH. THE DATA ALSO SHOW THAT IN THE STEADY-FLOW MODE THE MEDIAN AND CENTER LANES BEHAVE SIMILARLY, BUT THE CURB LANE IS SIGNIFICANTLY DIFFERENT. THE CURB LANE HAS ONLY ABOUT 86 PERCENT OF THE CAPACITY OF THE CENTER AND MEDIAN LANES. /AUTHOR/

Supplemental Notes:

Paper sponsored by Committee on Theory of Traffic Flow and presented at the 48th Annual Meeting. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

Monograph Accession #:

01410219

Language:

English

Authors:

Mika, H S
Kreer, J B
Yuan, L S

Pagination:

pp 1-12

Publication Date:

1969

Serial:

Highway Research Record

Issue Number: 279
Publisher: Highway Research Board

Media Type:

Print

Features:

Figures (15) ; References (3) ; Tables (2)

Uncontrolled Terms:

Steady flow

Old TRIS Terms:

Subject Areas:

Highways; Operations and Traffic Management

Files:

TRIS, TRB

Created Date:

Aug 15 2004 2:36AM

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