Ingenieria de transito

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FACULTY OF ENGINEERING DEPARTMENT OF CIVIL ENGINEERING SECTION TRAFFIC AND INFRASTRUCTURE KASTEELPARK ARENBERG 40, B-3001 HEVERLEE, BELGIUM

KATHOLIEKE UNIVERSITEIT LEUVEN

Course H 111

Verkeerskunde Basis

Traffic Flow Theory

May 2002 Prof. L.H. Immers S. Logghe

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Preface
This part of the course Basics of Traffic Engineering (H111) deals with the theory oftraffic flow. This theory studies the dynamic properties of traffic on road sections. We begin this course with a theoretical framework in which the characteristics of traffic flow are described at the microscopic level. We then examine a number of dynamic models that were formulated on the basis of empirical research. We conclude with a discussion of some recent observations on congestion. Thetheories and models that will be discussed are developed on the basis of numerous observations on motorways. There is a difference between motorways and lower order roads such as provincial roads and urban streets. For the latter it are the intersections that dominate flow characteristics to a large degree. Traffic flow on intersections is the subject of a separate workshop onSignal-Controlled Intersections (H112). This text is a second version. Remarks and suggestions continue to be appreciated. Heverlee, May 2003

L.H. Immers S. Logghe

email: traffic@bwk.kuleuven.ac.be tel: 0032-16-321669 0032-16-321670 address: Katholieke Universiteit Leuven Departement Burgerlijke Bouwkunde Sectie Verkeer en Infrastructuur Kasteelpark Arenberg 40 B-3001 Heverlee (Belgium)Translated from the Dutch by Leni Hurley and Jim Stada (January 2005)

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Contents
1 2 TRAJECTORIES AND MICROSCOPIC VARIABLES ........................................................................ 1 MACROSCOPIC VARIABLES ..................................................................................................................... 3 2.1 2.2 2.3 2.4 2.5 2.6 3 A MEASUREMENTINTERVA L ........................................................................................................................... 3 DENSITY............................................................................................................................................................. 4 FLOWRATE........................................................................................................................................................ 6 MEAN SPEED...................................................................................................................................................... 6 RELATIVE OCCUPANCY .................................................................................................................................... 9CONCLUSION..................................................................................................................................................... 9

FUNDAMENTAL DIAGRAM......................................................................................................................10 3.1 3.2 3.3OBSERVATIONS...............................................................................................................................................10 THE FUNDAMENTAL DIAGRAMS...................................................................................................................12 MATHEMATICAL MODELS FOR THE FUNDAMENTAL DIAGRAMS..............................................................13

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MACROSCOPIC TRAFFIC FLOW MODEL........................................................................................15 4.1 DERIVATION AND FORMULATION.................................................................................................................15 4.2 CHARACTERISTICS..........................................................................................................................................17 4.3 SHOCK...