skip to main content
article

Urban Network-Wide Traffic Variables and Their Relations

Published: 01 February 1987 Publication History

Abstract

<P>Time-lapse aerial photography over the Central Business Districts CBD of Austin and Dallas, Texas, has been employed to determine the averages of concentration, speed and fraction of vehicles stopped and to examine the relations among such network-wide averages including the flow which was measured on the ground simultaneously. The results have indicated that the average flow in a street network may indeed be expressed as the product of the space mean speed and concentration. Simultaneous ground experiments have also been conducted in the Austin CBD to investigate the reasonableness of the assumptions of the “two-fluid model,” a curvilinear relation between the trip time and stop time per unit distance, which may be used in characterizing the quality of traffic service in urban street networks. As a result of these simultaneous ground experiments and aerial observations, the assumptions of the model have been verified. Moreover, relations between the fraction of vehicles stopped and concentration as well as between speed and concentration have allowed the two-fluid model to be used to compare the quality of traffic service in various street networks under the same level of concentration. The two-fluid model may then be used to predict, for a given change in vehicular concentration in a street network, the resulting changes in the averages of speed, fraction of vehicles stopped, flow, etc. This is particularly useful as a performance model in urban planning where for a given concentration it is desirable to predict the resulting traffic conditions.</P>

References

[1]
M. PELEG, L. STOCH AND U. ETROG, "Urban Traffic Studies from Aerial Photographs," Transportation 2, 373-390 (1973).
[2]
J. E. ASHWOOD AND P. F. INGLIS, "Time-Lapse Aerial Photography: Application to Traffic Surveys," Traffic Engrg. Control 16, 19-21 (1975).
[3]
M. VANMANS, "Aerial Monitoring of Road Traffic," Transport Environment Circulation, No. 19 (November), 1976.
[4]
K. SMITH, "Analyza Gradskog Prometa iz Podataka Aerosnmaka," Goedetskih List, Savez Geodetskih Inzenjera i Geometara, Vol. 31, No. 416, Zagreb, Yugoslavia, 1977.
[5]
J. W. GODFREY, "The Mechanism of a Road Network," Traffic Engrg. Control 11, 323-327 (1969).
[6]
R. T. BAKER AND D. OWENS, "The Use of Aerial Photography for Assessing Traffic Control Systems in Glasgow," TRRL Monograph 93UC, Transport and Road Research Laboratory, Crowthorne, England, 1974.
[7]
A. WILLIAM AND D. R. GORDON, "Monitoring Area Control." Traffic Engrg. Control 16, 379-382 (1975).
[8]
J. B. GARNER AND J. UREN, "A Digital System for Urban Traffic Flow Data," Traffic Engrg. Control 19, 389-391 (1978).
[9]
M.-F. CHANG AND R. HERMAN, "An Attempt to Characterize Traffic in Metropolitan Areas," Trans. Sci. 12, 58-79 (1978).
[10]
R. HERMAN AND I. PRIGOGINE, "A Two-Fluid Approach to Town Traffic," Science 204, 148-151 (1979).
[11]
M.-F. CHANG AND R. HERMAN, "Trip Time Versus Stop Time and Fuel Consumption Characteristics in Cities," Trans. Sci. 15, 183-209 (1981).
[12]
S. ARDEKANI, V. TORRES VERDIN AND R. HERMAN, "El Modelo Bifluido y La Calidad del Transito en La Cuidad de Mexico," Revista Ingenieria Civil, Colegio de Ingen-ieros Civiles de Mexico, January/February 1985.
[13]
R. HERMAN AND S. ARDEKANI, "Characterizing Traffic Conditions in Urban Areas," Trans. Sci. 18, 101-140 (1984).
[14]
S. ARDEKANI AND R. HERMAN, "Quality of Traffic Service," Research Report 304-1, Center for Transportation Research, Bureau of Engineering Research, The University of Texas at Austin (June), 1982.
[15]
S. ARDEKANI, "The Two-Fluid Characterization of Urban Traffic: Theory, Observation, and Experiment," Ph.D. dissertation, University of Texas at Austin, 1984.
[16]
D. C. GAZIS, R. HERMAN AND R. POTTS, "Car-Following Theory of Steady State Traffic Flow," Opns. Res. 7, 499-505 (1959).
[17]
D. C. GAZIS, R. HERMAN AND R. W. ROTHERY, "Nonlinear Follow-the-Leader Models of Traffic Flow," Opns. Res. 9, 545-567 (1961).
[18]
H. MAHMASSANI, J. C. WILLIAMS AND R. HERMAN, "Investigation of Network-Level Traffic Flow Relationships: Some Simulation Results," Trans. Res. Rec. 971, 121-130, 1984.
[19]
"Traffic Network Analysis with NETSIM--A User Guide," Implementation Package FHWA-IP-80-3, Federal Highway Administration, U.S. Department of Transportation, Washington, D.C., 1980.
[20]
S. ARDEKANI, "Quality of Traffic Service in Urban Street Networks," M.S. thesis, University of Texas at Austin, 1981.
[21]
J. C. WILLIAMS, H. S. MAHMASSANI AND R. HERMAN, "Analysis of Traffic Network Flow Relations and Two-Fluid Model Parameter Sensitivity," Trans. Res. Rec. 1005, 95-106, 1985.
[22]
Y. ZAHAVI, "Traffic Performance Evaluation of Road Networks by the ¿-Relationship," Part 2. Traffic Engrg. Control 14, 292-293 (1972).
[23]
D. R. DREW AND C. J. KEESE, "Freeway Level-of-Service as Influenced by Volume and Capacity Characteristics," Highway Research Record No. 99, Highway Research Board, Washington, D.C., 1965.
[24]
D. J. BUCKLEY AND J. G. WARDROP, "Some General Properties of a Traffic Network," Australian Road Res. 10, 21-31 (1980).
[25]
R. C. BRINKER AND P. R. WOLF, Elementary Surveying, Ed. 6, Chap. 25, T. Y. Crowell, New York, 1977.
[26]
R. E. DAVIS, F. S. FOOTE, J. M. ANDERSON AND E. M. MIKHAIL, Surveying Theory and Practice, Ed. 6, Chap. 16, McGraw-Hill, New York, 1981.

Cited By

View all

Recommendations

Comments

Information & Contributors

Information

Published In

cover image Transportation Science
Transportation Science  Volume 21, Issue 1
February 1987
61 pages

Publisher

INFORMS

Linthicum, MD, United States

Publication History

Published: 01 February 1987

Qualifiers

  • Article

Contributors

Other Metrics

Bibliometrics & Citations

Bibliometrics

Article Metrics

  • Downloads (Last 12 months)0
  • Downloads (Last 6 weeks)0
Reflects downloads up to 28 Dec 2024

Other Metrics

Citations

Cited By

View all

View Options

View options

Media

Figures

Other

Tables

Share

Share

Share this Publication link

Share on social media