00824508

Component

https://doi.org/10.3141/1776-22

http://scholar.google.com...LSON&publication_year=2001

Traffic congestion is a major problem on U.S. highways. Studies and modeling of congestion can have important implications for efficiency, safety, and planning of transportation systems. A variety of theoretical models have been proposed to explain the behavior of congested traffic, including the recent interesting postulation of "synchronized flow" states and the treatment of these as phases (in the statistical mechanics sense). However, empirical methods for the identification and characterization of such patterns of congestion have been hampered by a lack of objective and quantitative characterizations of these patterns. An empirical study of the patterns of traffic in a data set from a congested, five-lane basic section of freeway is presented. These data were collected by videogrammetry, which provides additional information (on the spatial variation) in comparison with the information provided by other sensor technologies. With these data, a macroanalysis of the relationships among flow, density, and velocity was performed, and a linear (decreasing) relationship between velocity and density was found, with the attendant quadratic dependence of flow on density. Through a microanalysis, it was observed that depressions in velocity under congested conditions appear to be correlated with "constrictions" (waves of reduced speed between two waves of higher speed) that propagate backward, and a signal detection algorithm, based on convolutions of the density gradient, was designed for recognition of these events in a time series.

This paper appears in Transportation Research Record No. 1776, Traffic Flow Theory and Highway Capacity 2001.

English

p. 167-177

2001

Transportation Research Record

0309072344

Figures (9) ; References (22)

Algorithms; Bottlenecks; Detection and identification; Freeways; Microanalysis; Pattern recognition systems; Traffic congestion; Traffic density; Traffic flow; Traffic speed

Constrictions (Traffic flow); Macroanalysis; Videogrammetry

Highways; Operations and Traffic Management; I71: Traffic Theory

TRIS, TRB

Feb 5 2002 12:00AM

• ANALYSIS OF ARRIVAL TYPE ESTIMATION PROCEDURES
• CAPACITY AN UNSIGNALIZED INTERSECTIONS DERIVED BY CONFLICT TECHNIQUE
• CAPACITY ESTIMATIONS FOR TYPE B WEAVING AREAS BASED ON GAP ACCEPTANCE
• CHARACTERISTICS OF PASSING AND MEETING MANEUVERS ON EXCLUSIVE BICYCLE PATHS
• DEFINING FREEWAY CAPACITY AS FUNCTION OF BREAKDOWN PROBABILITY
• DELAY MODEL FOR PLANNING ANALYSIS OF MAIN-LINE TOLL PLAZAS
• DELAY MODEL FOR RIGHT-TURN LANES AT SIGNALIZED INTERSECTIONS WITH UNIFORM ARRIVALS AND RIGHT TURNS ON RED
• DERIVATION OF CAPACITY EQUATION FOR ROUNDABOUT ENTRY WITH MIXED CIRCULATING AND EXITING FLOWS
• EFFECT OF WEATHER ON FREE-FLOW SPEED
• ESTIMATING VEHICLE STOPS AT UNDERSATURATED AND OVERSATURATED FIXED-TIME SIGNALIZED INTERSECTIONS
• ESTIMATION OF DE FACTO LEFT-TURN LANES AT SIGNALIZED INTERSECTIONS
• EXAMINATION OF EFFECT OF DRIVER POPULATION AT FREEWAY RECONSTRUCTION ZONES
• FREEWAY NETWORK SIMULATION AND DYNAMIC TRAFFIC ASSIGNMENT WITH METANET TOOLS
• FREEWAY QUALITY OF SERVICE: WHAT REALLY MATTERS TO DRIVERS AND PASSENGERS?
• FREEWAY SYSTEMS RESEARCH BEYOND "HIGHWAY CAPACITY MANUAL" 2000
• HIGHWAY CAPACITY ANALYSIS AFTER "HIGHWAY CAPACITY MANUAL" 2000
• INTERVAL DISTRIBUTION FOR EXCLUSIVE, MIXED-USE BICYCLE PATHS
• MODEL OF FREE-FLOW SPEED FOR INDIANA ARTERIAL ROADS
• MULTIMODAL LEVEL-OF-SERVICE ANALYSIS AT PLANNING LEVEL
• MULTIVARIATE VEHICULAR TRAFFIC FLOW PREDICTION: EVALUATION OF ARIMAX MODELING
• NONLOCAL CONTINUOUS-SPACE MICROSCOPIC SIMULATION OF PEDESTRIAN FLOWS WITH LOCAL CHOICE BEHAVIOR
• PERCENT TIME-SPENT-FOLLOWING AS PERFORMANCE MEASURE FOR TWO-LANE HIGHWAYS
• PREDICTING RIGHT TURNS ON RED
• SATURATION FLOW ESTIMATION BY TRAFFIC SUBGROUPS
• SHOCK WAVE AND CUMULATIVE ARRIVAL AND DEPARTURE MODELS: PARTNERS WITHOUT CONFLICT
• SIMULATION-BASED STUDY OF TRAFFIC OPERATIONAL CHARACTERISTICS AT ALL-WAY-STOP-CONTROLLED INTERSECTIONS
• STOCHASTIC MODELING AND DESIGN OF VEHICULAR AND PEDESTRIAN NETWORKS
• USE OF IMAGE ANALYSIS TO ESTIMATE AVERAGE STOPPED DELAYS PER VEHICLE AT SIGNALIZED INTERSECTIONS