00378814

Component

http://onlinepubs.trb.org...s/trr/1983/905/905-004.pdf

https://scholar.google.co...lter&publication_year=1983

The reliability of classified traffic count data collected for the planning and operation of highway systems is examined. Manual classified count data are subject to serious errors, whereas automatic vehicle classification with modern microprocessor technology may have other accuracy problems. Accuracy checks carried out in the United Kingdom are described for two automatic classification systems--for simple classification by using inductive loops alone and for detailed classification by using loops and axle detectors in combination. An evaluation of automatic classification equipment, including these simple and detailed systems, has been carried out in the United States by the Maine Department of Transportation. The results of these studies are described. The accuracy of simple vehicle classification based on vehicle length alone is limited by the fundamental properties of inductive-loop sensors. However, at sites with good lane discipline, the accuracy of classification is likely to be sufficient for most routine purposes such as the measurement of passenger-car-equivalent flows. Tests in the United States have shown that the reduced reliability of pneumatic-tube sensors leads to poor classification accuracy when these sensors alone are used for vehicle detection. More detailed vehicle classification methods can give greater accuracy, in excess of 90 percent, but as traffic conditions deteriorate, accuracies reduce. In the detailed classification method, there are difficulties in discriminating between certain cars, vans, and trucks, particularly where lane discipline is poor. Further developments of automatic classification techniques are currently in progress, and improvements are anticipated under urban traffic conditions and in the portability of detailed classification equipment. However, simple classified counters are already available and already have a part to play in displacing unreliable manual counts. Future trends in labor and microprocessor costs are anticipated to be such that as new developments become available, their rapid exploitation will become increasingly attractive. (Author)

Publication of this paper sponsored by Committee on Traffic Flow Theory and Characteristics. 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

00386621

HS-036 181

pp 17-27

1983

Transportation Research Record

62nd Annual Meeting of the Transportation Research Board

Print

Figures (8) ; References (9) ; Tables (3)

Accuracy; Automation; Automobiles; Axles; Field studies; Loop detectors; Microprocessors; Passenger car equivalence; Reliability; Sensors; Traffic counting; Traffic flow; Trucks; Vans; Vehicle classification

Field data

Highways; Motor Carriers; Operations and Traffic Management; I71: Traffic Theory

HSL, TRIS, TRB

Dec 30 1984 12:00AM

• ANALYSIS OF EXISTING FORMULAS FOR DELAY, OVERFLOW, AND STOPS
• ANALYSIS OF TRANSYT PLATOON-DISPERSION ALGORITHM
• ANOTHER LOOK AT BANDWIDTH MAXIMIZATION
• APPLICATION OF COUNTING DISTRIBUTION FOR HIGH-VARIANCE URBAN TRAFFIC COUNTS
• CALIBRATION OF TRANSYT PLATOON DISPERSION MODEL FOR PASSENGER CARS UNDER LOW-FRICTION TRAFFIC FLOW CONDITIONS (ABRIDGMENT)
• CANDIDATE ACCIDENT SURROGATES FOR HIGHWAY SAFETY ANALYSIS
• COMMON BIAS IN BEFORE-AND-AFTER ACCIDENT COMPARISONS AND ITS ELIMINATION
• COMPARATIVE ANALYSIS OF SIGNALIZED-INTERSECTION CAPACITY METHODS
• COMPARISON OF SOAP AND NETSIM: PRETIMED AND ACTUATED SIGNAL CONTROLS
• DELAY MODELS OF TRAFFIC-ACTUATED SIGNAL CONTROLS (DISCUSSION AND CLOSURE)
• DERIVATION OF EQUATIONS FOR QUEUE LENGTH, STOPS, AND DELAY FOR FIXED-TIME TRAFFIC SIGNALS
• DETERMINING CAPACITY AND SELECTING APPROPRIATE TYPE OF CONTROL AT ONE-LANE TWO-WAY CONSTRUCTION SITES
• DEVELOPMENTAL STUDY OF IMPLEMENTATION GUIDELINES FOR LEFT-TURN TREATMENTS
• EFFECTIVENESS EVALUATION BY USING NONACCIDENT MEASURES OF EFFECTIVENESS (ABRIDGMENT)
• EVALUATING NEED FOR ACCIDENT-REDUCTION EXPERIMENTS
• EVALUATION OF DYNAMIC FREEWAY FLOW MODEL BY USING FIELD DATA (DISCUSSION AND CLOSURE)
• MINIMIZING COST OF MANUAL TRAFFIC COUNTS: CANADIAN EXAMPLE
• OPTIMIZATION MODEL FOR ISOLATED SIGNALIZED TRAFFIC INTERSECTIONS
• PASSENGER-CAR EQUIVALENTS FOR RURAL HIGHWAYS (DISCUSSION)
• SINGLE-LANE CAPACITY OF URBAN FREEWAY DURING RECONSTRUCTION (ABRIDGMENT)
• SKELETON PROCEDURE FOR EVALUATION OF HIGHWAY SAFETY IMPROVEMENTS ON A ROAD NETWORK
• SPEEDS AND FLOWS ON AN URBAN FREEWAY: SOME MEASUREMENTS AND A HYPOTHESIS
• SURROGATE MEASURES FOR ACCIDENT EXPERIENCE AT RURAL ISOLATED HORIZONTAL CURVES
• TANDEM TOLL BOOTHS FOR THE GOLDEN GATE BRIDGE
• TANDEM TOLL COLLECTION SYSTEMS (ABRIDGMENT)
• TRAFFIC DATA-COLLECTION SYSTEMS: CURRENT PROBLEMS AND FUTURE PROMISE (ABRIDGMENT)