01349733

Component

http://www.trb.org/Publications/Blurbs/165625.aspx

The paper presents traffic speed models developed on the basis of numerous measurements. In studies of the speed–flow relationships the following research issues were analyzed: impacts of the speed limit, traffic flow, traffic flow composition, and time of day on speed flow; and impacts of qualitative road and roadside features on free-flow speed (cross sections, road function, accessibility, intensity of development, and roadside pedestrian traffic). The research included road sections with numerous constraints of traffic freedom. Such sections comprise sections of roads through built-up areas (small communities and towns). The regression analyses, with use of generalized multiple regression, was the basic tool in investigations. Additionally, in analyzing data from speed measurements, the classic form of the logit function for a multiple-valued regression was applied. The analyses showed that even at general and posted speed limits the characteristic traffic flow–speed relations can be identified. The shape of these relations is characteristic for empirical results in which spread of recorded values is typical for randomness and impacts of local factors. Average speed in traffic flow depends not only on geometrical alignment of a road cross section but also on local factors as well as speed limits. Speed in free-flow traffic is significantly influenced by qualitative road and roadside characteristics. Most important of these factors are: type of cross section, intensity of roadside development, and accessibility of the road.

01349716

English

p 85

2011-6

Transportation Research Circular

Greenshields 75 Symposium

Web

Accessibility; Alignment; Flow speed relationships; Free flow speeds; Logits; Multiple regression analysis; Real estate development; Speed limits; Traffic flow; Traffic flow theory; Traffic models

Highways; Operations and Traffic Management; I71: Traffic Theory

TRIS, TRB

Aug 12 2011 2:16PM

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• A Stochastic Macroscopic Modeling Framework to Interpret the Fundamental Diagram
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• Bird’s Eye Perspective on Traffic Flow: New Insights from Observing Traffic from a Helicopter
• Calibrating Speed–Density Functions for Mesoscopic Traffic Simulation
• Calibration of Steady-State Car-Following Models Using Macroscopic Loop Detector Data
• Effect of Lane-Change Maneuvers on a Simplified Car-Following Theory
• Empirical Relation Between Stochastic Capacities and Capacities Obtained from the Speed-Flow Diagram
• From Inductance Loops to Vehicle Trajectories
• Fundamental Diagram for Signalized Arterials: An Empirical Analysis Using High-Resolution Traffic Data
• Fundamental Diagram on Urban Roads: Myth or Truth?
• Greenshields’ Legacy: Highway Traffic
• Greenshields’ Legacy: Urban Streets
• Lane-Change Maneuver Detection with Differential Global Positioning System Data from Probe Vehicle
• Measuring Traffic Flow Using Real-Time Data
• Modern Approaches to Basic Traffic Modeling: Three-Phase Traffic Theory
• Quality of Service Beyond the Traditional Fundamental Diagram
• Strategies to Improve Dissipation into Destination Networks Using Macroscopic Network Flow Models
• Traffic Flow Prospectives: From Fundamental Diagram to Energy Balance
• Traffic Flow Theory Historical Research Perspectives
• Treiterer’s Legacy: Traffic Flow Measurements and Characteristics